Hoa Sinh Dong Vat

8/9/2019 Hoa Sinh Dong Vat

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I HC THI NGUYN

TRNG I HC NNG LM

Ch bin: TS. TRN T

TS. TRN T - ThS. C TH THU NGA

GIO TRNHSINH HA HC NG VT

NH XUT BN NNG NGHIP

H NI - 2008


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LI NI U

Sinh ho hc ng vt l mt mn hc csca nhiu chuyn ngnh trong cctrngi hc nhchuyn ngnh Sinh hc, Chn nui Th y, Nui trng thy sinhCng ngh sinh hc . . . y l mn hc c tnh cht bc cu gia khoa hc cbnnhsinh hc, ho hc vi khoa hc chuyn ngnh nhdinh dng hc, di truyn hc,cng ngh protein, cng ngh gen, ging vt nui, sinh l hc, bnh l hc... Cho nn,thng qua mn hc ny sinh vin snm c csho sinh vnhu cu dinh dngcng nhngun gc, nguyn nhn gy bnh ng vt.

Gio trnh sinh ho hc ng vt do tp thtc gi bin son:

1. TS. Trn T (Ch bin): Chng2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15

2. ThS. C Th Thu Nga: Chng 1

Ni dung ca gio trnh c 15 chng bao gm 2 phn chnh: sinh ho hc tnhv anh ho hc ng . Sinh ho hc tnh scung cp nhng kin thc cbn vthnh

phn v cu to ho hc ca cc cht c trong cthng vt. Sinh ha hc ng scung cp nhng kin thc cbn vqu trnh trao i cht, schuyn hoa ca cccht v mi lin quan gia cc qu trnh chuyn ha trong cthng vt.

Chng ti hy vng rng gio trnh sinh ha hc ng vt ny s l ti liu hc

tp b ch sinh vin ngnh Chn nui, Th y ca cc trngi hc Nng nghip,ng thi cng l ti liu tham kho cho cc nh chuyn mn v cc c gi quan tmn lnh vc sinh ha hc.

Trong qu trnh bin son, chng ti rt cgng tham kho cc ti liu trongv ngoi nc nhm m bo tnh chnh xc, tnh cbn, tnh hin i v tnh thctin. Tuy nhin, gio trnh skhng trnh khi nhng thiu st. Chng ti xin chnthnh cm n v sn sng tip thu cc hn ng gp tmi tng lp c gi khi tipcn vi gio trnh ny chng ti kp thi bsung, sa cha nhm p ng ngy mt

tt hn .Tp th tc gi bin son


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Mu

GII THIU MN SINH HO HC

1. I TNG V NHIM V NGHIN CU CA MN HCSinh ho hc (Biochemistry) hay cn gi l ho hc sinh vt - l mt mn khoa

hc nghin cu hin tng sng, ch yu v mt ho hc. N l mt b phn cangnh khoa hc nghin cu v s sng ni chung, tc l ngnh sinh hc.

S sng bao gm nhiu hin tng rt phc tp c dnh hu n vt l, ho hc,cho: nn hiu c s sng v tin ti iu khin n ta cn phi nm c cc qutrnh c sca n. Nhim v ny c hai mn sinh l v sinh ho thc hin. Mnsinh l nghin cu cc hin tng l hc ca s sng, cn sinh ho hc nghin cu cc

thnh phn v cc biu hin ho hc ca s sng.

Sinh ho hc c th chia lm 2 phn: sinh ho hc tnh v sinh ho hc ng vihai nhim v nghin cu khc nhau.

1.1. Sinh ho hc tnh

1.1. 1. Nhim v v i tng

Nhim v ca sinh ho hc tnh l phn tch nghin cu thnh phn cu to hohc ca tng loi m bo, cquan, ca tng loi sinh dch trong c th. V mt ny,

sinh ho hc gn vi ho hu c, nhn m ta c c khi nim c th v cu trcca cth sinh vt, cng nh v cc cht bin ho trong qu trnh trao i vt cht.

1. 1. 2. Phng php nghin cu

Phng php nghin cu ca sinh ho hc tnh phn ln da trn phng phpnghin cu ca ho hu cnh: chit xut v phn tch.

Ngoi ra, ngy nay ngi ta cn ng dng rng ri cc phng php hin i nhphn tch cu trc bng tia Rn - ghen, phng php siu ly tm, phng php in

di... trong vi chc nm gn y c nhng pht hin v vng quan trng.1.2. Sinh ho hc ng

1 .2 .1. Nhim v v i tng

Sinh ho hc ng c nhim v nghin cu cc qu trnh chuyn ho ca vtcht, cc bin i ca tng m bo trong qu trnh trao i vt cht, c th ni y mil phn ch yu ca mn sinh ho hc.

Trit hc Mc L-nin khng nh rng sng l mt hnh ..thc vn ng ca

vt cht S vn ng th hin qua cc du hiu chung m chng ta gi l "hotng sng"nh s kch thch, s sinh sn, s sinh trng v s pht dc, tnh di truyn


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v bin d... Nhng nu i su vo ta thy nn tng ca cc hin tng sng ni trnvn l qu trnh trao i vt cht.

Nh sinh l hc Nga S-tr-n p (1884) ni: "Theo di c ng i canhng cht t ngoi a vo cth (di hnh thc thc n, kh th...), cc bc bin

chuyn ca chng cc m bo, cquan v cui cng chng c a ra ngoi didng cc cht thi, l chng ta din tc lch s s sng".

Nhng qu trnh chuyn ho ca s trao i vt cht c tin hnh trong cc mbo, cc cquan ca c th. ng vt c nhiu cquan li c chuyn mn hocao thm v chuyn trch v mt hay mt s phn ng chuyn ho, v mt ny sinhho hc ng cn c gi l sinh ho hc chc nng.

V d:

- Gan chuyn trch v tng hp mt s loi protein, mt s vitamin, khc

cht...

- Cc chc nng phn ho glucose ly nng lng co dn.

- Thn tham gia qu trnh bi tit ur.

1.2.2. Phng php nghin cu

nghin cu sinh ho hc ng ngi ta dng nhiu phng php khc nhau,nhng gp rt nhiu kh khn v cc qu trnh ho hc cth din bin vi tc rtln v h thng phn ng li v cng phc tp. Hn th na, cth li khng phi lni m chng ta c th p dng nhng thao tc phn tch th bo.

u th k XIX ngi ta dng cc phng php nh nghin cu ln menru, chit xut nghin cu cn bng Nit, nghin cu dch tiu ho... Tuy kt qunghin cu em li nhng pht hin quan trng nhng nhng phn ng su kn nhtvn cn l iu b n i vi sinh ho hc.

Mi cho ti khi phng php nguyn tnh du ra i th hng lot cc phnng ca qu trnh trao i cht mi c khm ph v trnh by mt cch c h thng.

Thng qua cc hiu bit v s sng do sinh ho hc cung cp, ta s tr li tcng ln s sng mt cch c hiu qu hn. V d: trong chn nui th y, nhng kinthc v trao i vt cht gip ta t chc tt hn vic chm sc v nui dng gia sc;cn bit v s bt thng v ri lon ca chuyn ho s gip ta chn on chnh xc viu tr hiu qu nhiu bnh gia sc. Ngoi ra, sinh ho hc cn gip ta hiu su hncc vn chuyn mn nh: sinh l hc, bnh l hc, ni khoa, truyn nhim hc...

2. V TR MN HC

Sinh ho hc l mn khoa hc csc tnh cht bc cu gia khoa hc cbn vkhoa hc chuyn ngnh. Sinh ho hc, song song vi sinh l hc, s gip ta hiu suhin tng sng ca gia sc.


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V tr sinh ho hc trong khoa hc chn nui th y:

*i vi cn b chn nui: sinh ho hc c mt tm quan trng c bit. Nhckin thc v sinh ho hc ta s hiu c csho hc ca s pht trin ca gia sc;hiu c nhu cu ca tng loi gia sc theo tng giai on pht trin v sinh trng

ca n. Do trong vic lp ch chm sc, lp khu phn thc n, hoc trong vicchn ging v lai to, chng ta s c csl lun su sc v ton din hn.

* i vi cn b th y: Vic nghin cu sinh ho hc li cng cp thit. Muncha bnh tt phi hiu c cn bnh, m ngun gc ca hu ht cc bnh thnggp u dnh dng n s ri lon h thng trao i cht ca c th. V d nh cc

bnh v thiu sinh t, ri lon ni tit t, cc bnh vng tiu ho . . .

3. LCH SPHT TRIN CA SINH HA HC

Sinh ho hc l mn khoa hc c nhp pht trin rt nhanh chng. N chnh thnh r rt ch mi trn di 100 nm nay, gc r ca n bt ngun t cc mnkhoa hc khc nh ho hc, l hc, y hc, sinh hc...

Nhng mm mng u tin ca sinh ho hc c hnh thnh khi con ngi bit nghti vic ch thuc men, nhum vi vc, thuc da th, ru, ct gi thc

phm... n th k XVI - XVII nhm y ho hc (tiu biu l Paraxen) ra vicdng cc kin thc ho hc gii thch v can thip vo s sng. H cho rng cthgm ch yu c thu ngn, lu hunh v mui. Nu t l cc cht trong c th thng

bng th sc kho tt nu khng s pht sinh bnh tt.

V d:

- Lu hunh tng s sinh ra st

- Lng mui tng s sinh ph thng v tho d

- Thu ngn tng s sinh bi lit v r.

Tuy nhin l lun trn n by gich cn mang tnh cht lch s, nhng cnglao ca nhm y ho hc ny em li cho thc hnh mt s thuc thu ngn, st,

ch... c hiu lc. ng k nht l nhm ny cp n men trao i cht sinh th.Sau do thuyt sinh lc thnh hnh m thuyt ny b hn ch.

Sang u th k XIX mn ho hc tng hp c hnh thnh. Nhng vic tnghp cc cht c trong cth sinh vt vn cha thc hin c.

Nm 1828 V-le tng hp c ur t cc cht v c th ranh gii gia thgii v cv th gii hu cmi dn dn c sng t.

V-le tng hp ur t xyanua mun theo s sau:


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Sau V-le hng lot cc cht hu cc tng hp. Trong phi kn vic

tng hp hydrat carbon ca But-le-rp v Fisher, tng hp cht bo ca Bec-t-l.

Nm 1838 Mun-e bt u c nhng nghin cu t m v ho hc protein.

Cui th k XIX Fisher v a-nhi-lep-ski ra thuyt mch peptid.

Th k XIX cng l giai on pht sinh ca cc kin thc v men, vitamin,hormon nh:

+ Kic-gp (1 8 1 4) nghin cu bin i tinh bt thnh ng maltose, tin ramen amylase.

+ Lu-nin (l 854 - 1 937) xc nh vai tr cc vitamin

+ Le-be-ep v Cs-t-trep nghin cu hin tng ln men

+ Tip l cng trnh ca Pap-lp v ho hc chc nng. ng nghin cuthnh phn ho hc ca dch tiu ho v qu trnh tiu ho. ng thi ng cng lmsng t nhiu tnh cht ca cc enzym tiu ho v chng minh vai tr ca h thn kinh

trung ng trong qu trnh trao i cht.Sang u th k XX nhng .pht hin su sc ca Ba-kh ( 1 857- 1 946) v

Paladin (1 859- 1 922) v qu trnh oxy ho hon nguyn sinh hc km theo hintng gii phng nng lng lm sng t hng lot vn , trong c vn v sh hp m bo.

Ngy nay, sinh ho hc tr thnh mt h thng s gm nhiu chi nhnhln, nghin cu nhng chuyn trong nhiu phm vi. V d ta thy c sinh ho hcng vt, sinh ho hc thc vt, sinh ho hc vi sinh vt, enzym hc, sinh ho hc ditruyn...


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Chng 1

THNH PHN HA HC CA TBO V DCH THCTHNG VT

Thnh phn ho hc ca t bo v dch thcthng vt rt phc tp. T th

k XVII v XVIII nhiu nh khoa hc nghin cu thnh phn ho hc ca t bong vt Mc d, vi quan im ho hc hin i th cc nghin cu y cha tht y, nhng chng cng c ngha khoa hc v thc tin nht nh. Nhng nghin cuny chng minh rng trong thnh phn ca t bo ng vt v thc vt c protein,lipid, v nhng cht khc m c th s dng cho dinh dng v cc nhu cu khc.

Na cui th k XVIII, Labiaze khi nghin cu thnh phn nguyn t cc chtchit xut t t bo ng vt v thc vt, nhn thy rng chng c cu to t ccnguyn t nh carbon, hydro, oxy v nh.

V sau, vi cc phng php phn tch ho hc hin i ch ra rng thnhphn nguyn t cc cht ca c th l rt phc tp. Trong thnh phn ca chng cntm thy nhng nguyn t khc vi s lng rt khc nhau.

S phc tp v thnh phn ho hc ca cc t.bo c thng vt c ccnh nghin cu ho hc hu cchng minh. H tan thy trong t bo ng vt sc mt ca cc cht hu cphc tp nh protein, lipid, glucid v s lng ln cc chtc cu to n gin nh acid amin, amid, acid bo, cc dng aldchyd, ru, ke ton,

benzol, pyrol... n th k XIX, trong thnh phn t bo c thng vt ngi ta tm thy enzym, hormon, vitamin v cc cht c hot tnh sinh hc cao ng vai trquan trng trong trao i cht.

1.1. THNH PHN CC NGUYN T CA T BO CTH

Trong thnh phn cc cht ca t bo ng vt tm thy gn 60 nguyn t. Mtphn cc nguyn t ny c tt c cc ng vt, chng cn thit thc hin cc chcnng sng cbn. Nhng nguyn t khc ch c mt s loi ng vt v n quantrng chi vi cc loi ng vt nht nh, thng chng xut hin t bo ng

vt mt cch ngu nhin v sau li o thi khi cth. ~

i vi nhm th nht bao gm cc nguyn t: oxy, hydro, carbon, Nit, luhunh, phospho, calci, nam, kim, do, ma gi, st, km, ng, iod, ma ngan, co ban.

i vi nhm th hai bao gm: lui, nhm, lum, flo, bc, thu ngn, ch, ni ken,ban, molibden, vng, bo, than, crom... Tt c cc nguyn t ny c tm thy trong cth vi s lng rt nh v khng c tt c cc ng vt.

Hm lng trung bnh ca mt vi nguyn t trong c thng tt (% so vi

khi lng cth)


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Nguyn t % Nguyn t %

Oxy........................ 62,43

Cacbon.................. 21,15

Hydro................... 9,86Nit..................... 3,10

Canci.................... 1,90

Phospho............... 0,95

Kali..................... 0,23

Lu hunh............0,08

Clo...................... 0,08

Nam.................. 0,080

Ma gi................ 0,027

Iod.................... 0,014Flo................... 0,009

St.................... 0,005

Km.................. 0,003

Brom................. 0,002

Nhm................ 0,001

Kremni.............. 0,001

ng............... 0,00015

Qua s liu bng trn cho thy: trong t bo cthng vt hm lng chnhl oxy, carbon, hydro v nh. T cc nguyn t ny cu to nn cc hp cht hucch yu ca t bo l protein, lipid v glucid.

Nhng ng vt khc nhau c kh.nng tch lu loi nguyn t ny hay loinguyn t khc trong t bo ca chng. V d, mu ca ng vt c v cha st, mu

ca chn kh p v thn mm cha ng. Cc t bo ca c thng vt khc nhaucng c nng cc nguyn t khc nhau. V d, iod tp trung ch yu t bo tuyngip trng, li t bo phi, ng t bo gan, km t bo. sinh dc, thm t bothn kinh. .. Ngy nay khng nh rng cc nguyn t vi lng trong cth mc dus lng rt nh, nhng tm thy trong enzym v hormon. V d, trong enzym

peroxydase c st, enzym oxydase c ng, trong hormon tyrosin c iod...

Thnh phn cc nguyn t ca t bo ng vt ph thuc vo loi ng vt, latui, iu kin sng...

Hm lng cc thuyn t chnh trong cthmt sloingtt (%)

Nguyn t Mo Chut ch

Cc bon

Hydro

Nit

20,56

10,52

3,31

10,77

10,15

3,21

7,38

10,28

2,17

Trong thnh phn cc cht cn c cc nguyn t phng x nh: kim, rubidi, man,


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ri. Kali c ngha c bit khi nghin cu cc tia ~ v '. C thng vt c khnng gi cc nguyn t phng' x t mi trng mt thi gian vi hm lng nh.

1.2. CC HP CHT V CV HU CTRONG CTHNG VT

Cc nguyn ttrong cth di dng cc hp cht v cv hu cvi mc

phc tp khc nhau.Nhm cht th nht: protein, glucid, lipid, lipoid, nc v mui v clun lun

c trong thnh phn t bo ng vt.

Nhm cht th hai: amoniac, CO2, u r, acid uric, creatin, glycerin v cc chtkhc l cc sn phm phn gii ca nhm cht th nht hay sn phm ca qu trnhtng hp.

Nhm cht th ba l cc cht c hot tnh sinh hc nh enzym, hormon,

vitamin...Mt trong nhng lin kt ny trong t bo l dng phn t ho tan, dng th hai

l dng ton v dng th ba l trng thi keo.

Kt qu ca s lin kt cc cht vi nhau ca ba nhm cht ny s to thnh vs cc phc cht c thnh phn phc tp.

T l phn trm cc cht cbn mt s t bo ng vt c th hin bngsau:

Bng thnh phn ho hc mt stbo chnh ca cthng vt c v (%)T bo.

c Mu Gan No Da xng

Nc

Vt cht kh

Protein

Lipid v lipoid

Lucid

Cht hu c

Cht v c

72-78

22-28

18-20

3,0

0.6

1,0

1,0

79

21

9,0

1,0

0,1

0,14

0,9

60-80

20-40

15

3-20

1-15

Nhiu

Khng c

78

22

8,0

12-15

0,1

1,0-2,0

1,0

66

34

23

7,.0

C

C

0 6

20-25

75-80

26

Rt t

C

Rt t

45

1.3. NC TRONG CTHNG VT

Nc trong cthng vt nng nghip chim trung bnh khong 2/3 khi lng

c th. Hm lng nc gim dn theo la tui. S phn b nc trong t bo cngkhc nhau. C loi t bo chim ti 80% hoc ln hn, nhng c loi t bo ch c 1


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0% hoc t hn. Mt phn nc trong cth nm trng thi t do, nhng phn ln trng thi lin' kt. Protein v mt s hp cht khc ca cth tn ti trng thi keo.

Nc trong cc h thng keo dng hydrat, mu61 hoc lin quan vi lc trngphng. Loi lin kt ny ca nc rt quan trng i vi c tnh ca n trong t bong vt.

S hiu bit v qu trnh lin kt v bi tit nc do cc t bo ca c th c ngha rt ln trong vic nghin cu s trao i nc ng vt.

Bng T lnc trong tbo ng vt

T bo T l T bo T l

Rng

XngT bo m

T bo gn

T bo sn

Gan

T bo m lin kt

timThn

Cht xm ca no

10

2230

49

55

74

79

7983

85

Cht trng ca no

Tu sngDa

C

Lch

Phi

Mu

Bch huytDch d dy

Nc bt

70

6972

76

76

78

79

9597

99


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Chng 2

PROTEIN

2.1. I CNG V PROTEIN

2.1.1. Tn giProtein theo ting Hy Lp "Protos" - c ngha l u tin, quan trng nht, iu

cho chng ta thy c vai tr quan trng bc nht ca protein i vi cuc sng.

2.1.2.nh ngha protein

Ngi ta thng nh ngha protein theo hai quan im:

2.1.2.1. Theo quan im ho hc

Cc nh ho hc cn c vo thnh phn v cu to ho hc ca protein nh

ngha. H cho rng protein l nhm cht hu cln vi hai c im ng ch l:- Phn t c cha Nit(azt)

- Trng lng phn t rt cao.

C th ni rng: Protein l cht trng phn cao phn t ca cc acid amin.

2.1.2.2. Theo quan dim sinh vt hc

Cc nh sinh vt hc li da Vo gi tr dinh dng v tm quan trng caprotein i vi s sng nh ngha. Theo quan im sinh vt hc thprotein l chtmang ssng. iu ny c ng-ghen pht trin rt rnh mch trong tc phm niting "Chng y rinh v "Php bin chng t nhin". n ghen vit:

"... S sng l phng thc tn ti ca cc th protein, bn cht ca n bao hmtrong hin tng lun lun t ti to nhng cu trc ho hc ca nhng thy". ngvit ti p: "Bt c ni no c hin tng sng chng ta u thy n i lin vi th

protein v bt c ni no c protein khng qu trnh tan r, chng ta bt buc phigp hin tng sng", "Ngay nhng sinh vt hng nht m chng ta bit, bn thncng l mt ht protein".

Ni dung nh ngha v s sng ca n ghen:

- S sng l phng thc tn ti ca protein. Protein y l mt c th honchnh c t chc, ch khng phi l mt loi protein ring bit no .

- Th protein y cha ng c lp nucleoprotein.

- Ni dung chnh ca s vn ng sng l s trao i cht, s t thay ci micc nguyn t ho hc m hin tng ny khng th c trong mt cht v sinh. Bn

biu hin c th ca s sng l:

+ C kh nng vn ng v p nhn kch thch bn ngoi


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+ C kh nng sinh trng, pht trin v sinh sn

+ C kh nng di truyn v bin d

+ C kh nng trao i vt cht vi mi trng bn ngoi

Trong tt c 4 biu hin trn th biu hin th t ca s sng l quan trng nht.

Bi v c trao i vt cht th cth mi c kh nng vn ng v p ng c cckch thch, mi c kh nng sinh trng, pht trin, sinh sn v mi c kh nng ditruyn, bin dc.

2.1.3. Cc nguyn tho hc ca protein

Qua phn tch ho hc ngi ta xc nh c trong protein c cc nguyn t sauy (tnh theo % vt cht kh):

- Cacbon:........................ 50,6 - 54,5

- Oxy:.............................21,5 - 23,5

- Hydro:.......................... 6,5 - 7,3

- Nit:............................ 15,0 - 17,6 (trung bnh 16%)

- Lu hunh:..................... 0,3 - 2,5

- Phospho:....................... 1,0 - 2,0

Nhn thy rng Nitlun lun c trong protein mt lng t thay i, trn di

1 6% . Trong thc hnh t l ny c dng vo vic nh lng protein (phng phpKjeldahl).

s lng protein = S lng Nx 6,25 g.

(y 6,25 g protein tng ng vi lo Nit).

Cng do no l nguyn t thng trc ca protein nn trong ngn ng thngngy ngi ta dng ch "M" hiu ngm l protein.

Ngoi cc nguyn t ho hc k trn, trong thnh phn protein cn c cc nguynt vi lng v cc nguyn t siu vi lng. Mc du s lng cc nguyn t trong

protein rt th p (khong 0,3.10-3%) nhng chng ng vai tr quan trng trong qutrnh hot ng sng ca ng vt, c bit l trong thnh phn ca enzym v hormon.

V d:

Iod c trong tuyn gip trng

Li c m phi


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ng c tuyn gan

Km c tuyn sinh dc...

2.1.4. Vai tr sinh hc ca protein

protein gi vai tr rt quan trng trong tt c cc qu trnh sinh hc. ngha ng

k nht ca chng c th hin qua cc vai tr ch yu sau y:

Vai tr to hnh

Ngoi cc protein lm nhim v cu trc nh v vus, mng t bo, ta cn gpnhng protein thng c dng si nh: fibroin ca t tm, nhn; collagen, elastin cam lin kt, m xng... Cc cht ny c tc dng to hnh m bo bn v tnhmm do ca cc m lin kt.

Vai tr xc tc

Hu ht cc phn ng sinh ha hc xy ra trong c thu do cc protein cbit ng vai tr xc tc. Nhng protein ny c gi l enzym. Mc du gn yngi ta pht hin c mt loi ARN c kh nng xc tc qu trnh chuyn hatin ARN thng tin (pro-m ARN) thnh ARN thng tin im ARN), ngha l enzymkhng nht thit phi l protein. Tuy nhin, hu ht cc phn ng xy ra trong c thsng u c xc tc bi cc enzym c bn cht protein. V vy, ngi ta thngnh ngha enzym l nhng protein c kh nng xc tc c bit cho cc phn ng sinhha hc.

Vai tr bo v

Protein c chc nng chng li bnh tt bo v cth. l cc protein tham giavo h thng min dch. c bit nhiu loi protein thc hin cc chc nng ring bitto nn hiu qu min dch c hiu v khng c hiu. Cc protein min dch cnhc n nhiu nht l cc khng th, b th v cc cytokine. Ngoi ra, mt s proteincn tham gia vo qu trnh ng mu chng mt mu cho cth. Mt s loi c thsn xut ra nhng c t c bn cht protein nh enzym nc rn, lectin... c kh nngtiu dit k th bo v cth.

Vai tr vn chuyn

Trong c th ng vt c nhng protein .lm nhim v vn chuyn nhhemoglobin, mioglobin, hemocyanin vn chuyn O2, CO2 v H

+i khp cc m bo,cc c quan trong c th. Ngoi ra, cn c nhiu protein khc nh lipoprotein vnchuyn lipid, seruloplasmin vn chuyn ng (Cu) trong mu. Mt trong nhng

protein lm nhim v vn chuyn c nhc n nhiu nht l hemoglobin.

Vai tr vn ng

Nhiu protein lm nhim v vn ng co rt nh miosin v actin ca si c,chuyn dch v tr ca nhim sc th trong qu trnh phn bo...


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Vai tr dtrv dinh dng

Cc protein lm nhim v d tr nh casein ca sa, ovalbumin ca trung, feritinca lch (d tr st). . . Cc protein d tr ny chnh l ngun cung cp dinh dngquan trng cho cc t chc m, phi pht trin.

Vai tr dn truyn tn hiu thn kinhNhiu loi protein tham gia vo qu trnh dn truyn tn hiu thn linh i vi

cc kch thch c hiu sc t th gic rodopsin vng mc mt.

Vai tr iu ha

Nhiu protein c kh nng iu ha qu trnh trao i cht thng qua vic tcng ln b my thng tin di truyn nh cc hormon, cc protein c ch c hiuenzym... V din hnh l cc protein repressor vi khun c th lm ngng qu

trnh sinh tng hp enzym t cc n tng ng.Vai tr cung cp nng lng

Protein l ngun cng cp nng lng cho c th sng. Khi thy phn protein,sn phm to thnh l cc acid amin, t tip tc to thnh hng lot cc sn phmkhc trong c cc cetoacid, aldchyd v acid carboxylic. Cc cht ny u b oxyha dn to thnh CON v H2o, ng thi gii phng ra nng lng.

2.2. CU TO HA HC CA PROTEIN

2.2.1. Acid amin - n vcbn cu to nn phn tproteinVo u th k XIX (thi k ca nh ho hc H Lan Mulder) ngi ta cha

phn bit c protein ca ng vt v thc vt. Ngi ta tng rng protein l ngnht, ch khc nhau v s lng cc sinh vt.

Mi cho ti nm 1820 ln u tin Bracono dng kim v acid c thuphn protein nhit cao (100 - 1200c) V thu c Cc acid amin u tin, trong c tinh th glycocol.

Nm 1871 Lubavin cho thy rng protein di tc dng ca cc dch tiu hophn tch thnh cc acid amin.

c bit cng trnh ca Fisher (1901 - 1902) c ngha quan trng v vicnghin cu bn cht ho hc ca protein.

Tt c cc cng trnh nghin cu trn cho chng ta thy rng: thnh phn phnt ca protein l cc acid amin.

Ngy nay, ngi ta tm thy hn 200 acid amin khc nhau, nhng trong thnhphn ca protein t nhin thng c 20 loi acid amin.

2.2.1.1.nh ngha acid amin

Acid qun l mt acid hu c, m trong mt nguyn t hydro ca gc carbon


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alfa (Ca) c thay th bi nhm quan (NH2)

Nu trong mt acid amin c hai nhm qun th nhm quan th 2 nm v trcarbon cui cng k t nhm carboxyl (COOH).

V d:

2.2.1.2. Hot tnh quang hc ca acid amin

Ch tr glycin trong phn t cht ny khng c nguyn t carbon bt i, cn ttc cc acid amin cn li u c t nht mt nguyn t carbon bt i (tc l bn ha trca n c bo ha bi bn nhm nguyn t khc nhau - k hiu C*), do chngu c kh nng lm quay mt phng phn cc ca nh sng, ngha l chng u lnhng cht hot quang.

Tt c cc acid amin c trong thnh phn protein u c cu hnh L nguyn t

carbon a, cc acid amin c cu hnh D rt gp trong thin nhin.

Ch L cho ta bit cu lluul ca phn t ch khng cho ta bit hng gc quayca mt phng phn cc .

- Cc ng phn hu tuyn (lm quay mt phng phn cc sang phi) c khiu bng du (+)

- Cc ng phn t tuyn (lm quay mt phng phn cc sang tri) c k hiubng du (-)

Ngi ta qui c rng i vi glucid, cht aldehyd D-glyceric c chn lmcht tiu chun so snh, cn i vi acid amin L-serin c chn lm cht tiuchun.

a s cc acid amin dy D u c v ngt, cn cc acid qun thin nhin thuc


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dy L - th u c vng hoc khng v.

Cc acid amin tng hp u l nhng RAXEMAT khng c tnh hot quang,ngha l mt hn hp cng phn t ca dng D v dng L.

2.2.1.3. Cc phn ng ho hc c trng ca acid amin *Phn ng vi acid v

bazto thnh mui

ng dng: Do tnh cht lng tnh nn acid qun l nhng cht m tt, n nh pa.

*Phn ng vi acid Nit(hay l phn ng Van-slyke)

Tr thon v oxyprolin (hai cht ny l iminoacid) cc acid amin u phn ngvi lem no gii phng kh Nit:

ng dng: Cn c vo lng nh thot ra ngi ta c th tnh c hm lngca cid quan trong dung dch.

*Phn ng Sorensen (phn ng vi Aldehydformtc -formalin)

ng dng: Bng cch chun vi dung dch kim tiu chun ngi ta c th xcnh c hm lng acid amin c trong dung dch.

*Phn ng vi kim loi nng

Acid amin to thnh cc mui phc ni phn t vi cc chun ca kim loi nng,c bit l vi con Cu2+.


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*Phn ng Sangery l mt phng php ph bin nht dng xc nh acid amin trong mch

polvpen~id tu N.

Khi nghin cu tnh cht ha hc ca acid qun ta thy r nhm a-amin c thtrng hp vi dtronuobenzen. Trong mch polypeptid ch c mt nhm a-amin tdo. u N, khi trng hp s to thnh dinitrophenyl-polypeptid. Mi lin h ny rt

bn vng, do khi dng HCl thy phn protein s gii phng ra tt c cc acidnhn t do cng vi acid amin. nm u N di dng dinitrophenyl-aminoacid

(DNP-aminoacid). Sau bng phng php sc k c th d dng nhn bit tn caacid amin .

*Phn ng mu vi ninhydrin (trixetohydrinden)

Khi un nng cc acid D- quan vi ninhydrin, nu mi trng pH < 5 th chngs b oxy ho v phn gii thnh aldchyd tng ng, CO2 v NH3

Nu pH > 5 th s sinh hp cht mu lc.

Ngi ta c th tnh c hm lng acid amin tham gia trong phn ng bngcch nh lng kh CO2, NH3 hoc aldehyd va to thnh trong phn ng.

Phn ng ca acid amin vi ninhydrin c s dng nhiu nh tnh v nhlng acid amin, c bit l phng php sc k trn giy v sc k trn ct nha traoi ln nhmy phn tch acid amin tng do Spackman, Stein v Moose xng.Phn ng ny rt nhy, c th cho php ta xc nh c cc acid amin c nng rtnh (vi microgam).

2.2.1.4. Phn loi cc acid amin

C nhiu cch phn loi acid amin. Cc acid amin c th phn loi theo haiquan im: Quan im ho hc v quan im sinh vt hc

* Quan im ho hc (tc l xt v mt cu to phn t v cc ho tnh), ngi tathng chia acid amin ra:


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- Acid amin mch thng: Trong acid amin mch thng ph thuc vo s lngnhm quan (NH2) v nhm carboxyl (COOH) m li chia ra:

+ Acid monoamin- monocarboxylic (cha 1 nhm NH2 v 1 nhm COOH)

+ Acid monoamin- dicarboxylic (cha 1 nhm NH2 v 2 nhm COOH)

+ Acid diamin- monocarboxylic (cha 2 nhm NH2 v 1 nhm COOH)

- Acid amin mch vng: gm loi vng ng nht v loi d vng.

* Quan im sinh vt hc (tc l xt tm quan trng i vi s dinh dng cang vt). Theo quan im ny, acid amin gm hai loi:

-Loi khng thay thm c (indispensable amino acid) hay cn gi l acid aminthit yu (essential amino acid - EAA): y l loi acid amin rt cn thit cho c thng vt cho qu trnh sinh trng v pht trin. Cthng vt khng th t tng

hp c tho mn nhu cu ca bn thn m phi thng xuyn a t bn ngoivo vi thc n

i vi ng vt ni chung c 9 acid amin khng thay thc: Vang, leucin,isoleucin, treo nin, methionin, phenylalanin, tryptophan, ly sin, histidin.

Loi thay th c (dispensable amino acid) hay cn gi l acid amin khng thityu (nonessential amino acid - NEAA): tc l loi acid amin m cthng vt c tht tng hp c t cc nguyn liu sn c (cc acid bo, amiac, amid...). Nhm nygm cc acid amin cn li.

Cn phi ch thm rng khng phi mi acid amin u c tc dng v~ nhhng nh nhau i vi cc loi ng vt m mi gia sc, gia cm c nhng nhu cuc trng ca mnh i vi tng loi acid amin. C loi ng vt cn ti 10 acid aminkhng thay th (v d nhi vi g con th arginin l acid tin khng thay th), nhngc loi ng vt li ch cn 8 acid amin khng thay th (v d nh ngi th histidinc xp vo nhm acid amin thay th).

Mt s acid amin khng c xp vo nhm khng th thay th hay nhm thay

th m chng c xp vo nhm bn thay th (sm- dispensable) hay cn gi l bnthit yu (semi-essential). Thuc nhm ny c arginin, cystein, tyrosin. Arginin ccoi l bn thay thi vi ln v arginin c thc tng hp t glutamin. Tuy vy,s tng hp ny khng p ng nhu cu dinh dng trong giai on u ca qutrnh pht trin c th. Do khu phn cho ln sinh trng phi cha mt lngarginin nht nh. Nhiu nghin cu cho thy giai on sau khi thnh thc v tnh vgiai on mang thai ln c thng hp arginin vi s lng p ng nhu cu cachng, nhng khng p ng nhu cu tit sa ca ln ni. Cystein c thctng hp t methionin. Tuy vy, cystein v dng oxy ho ca n l cystin c thpng khong 50% nhu cu ca tng lng acid amin cha lu hunh (methionin,cystein). Tyrosin c tng hp t phenylalanin v c thp ng ti thiu 50% tng


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nhu cu ca tyrosin v phenylalanin, nhng n khng th l ngun duy nht v khngth thay th cho phenylalanin v n khng th chuyn c thnh phenylalanin.

2.2.1.5. Cc loi acid amin

C 20 loi acid amin tham gia vo cu trc ca m bo cn c vo nhm quan v

nhm carboxyl trong phn t m acid amin chia ra:Cc acid amin mch thng:


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2.2.2. Kt cu ca cc acid amin trong phn tprotein

(Cc kiu trn kt ca acid amin trong phn t protein)

Dng phng php thy phn ngi ta tm ra c n v cu to ca proteinl acid amin. Trong phn t protein s lng acid amin thng rt ln, cho nn ta cn

nghin cu xem chng lin kt vi nhau nh th no.

2.2.2.1. Cu trc bc mt ca protein - lin kt peptid (-CO - NH-)


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Cui th k XIX nh sinh ho hc Nga a-nhi-lep-ski ra gi thuyt rngcc acid amin lin kt vi nhau nhbn kt gia nhm carboxyl v nhm quan (- Co -

NH -) gi l mch peptid. ng ra thuyt ny khi nghin cu phn ng Biur ccdng protein.

Gi thuyt ca anhilepski ngay sau c nh sinh ho hc ngi c l

Fisher xc minh bng thc nghim. Fisher tch ring v nghin cu t m 19 acidamin v th tng hp cc peptid theo kiu phn ng sau y:

Dng dn xut cloranhydric ca mt acid bo no cho tc dng vi acid qunta sc mt hp cht trung gian. em n cho tc dng vi amiac ta s thu c mtdipeptid :

Dng phn ng ny nhn di chui peptid

Ngi ta thy tnh cht ca cc peptid tng hp c ging tnh cht ca snphm thu phn protein cha trit . Trong thc hnh ngi ta gi peptid thu phnc l pepton hoc albumose.

Do ta c th ni: Cscu trc bc mt ca protein l mch peptid (- Co -NH -), mch c hnh thnh gia nhm carboxyl ca acid amin th nht vi nhmquan ca aci quan ti p theo sau khi loi khu i mt phn t nc. y l lin ktng ho tr nn n rt bn vng.


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Nhphng php nghin cu tinh th bng quang tuyn Rn-ghen ngi ta thynhng mch peptid cu trc bc mt c hnh th v kch thc theo s sau:

Tu thuc vo s lng acid qun ta c dipeptid, tripeptid, tetrapeptid... v polypeptid. Tn gi nhng peptid n gin da theo tn ca acid amin h p thnh,nhng cht c - Co - u bin ui -in thnh -yl cht sau cng c - COOH th gi

nguyn tn. V d: glycyl- alanin.Tnh c trng ca protein khng nhng ph thuc vo s lng m cn ph

thuc vo th t sp xp ca cc acid amin trong chui peptid. Mi protein c slng v th t sp xp cc acid amin ring v nh vy n c chc nng ring.

Nu c 3 acid amin A, B v C ta c th sp xp thnh 6 peptid khc nhau ABC,ACB, BC, BCA, CAB, CBA, c ngha l 1. 2. 3 = 6

Qui tc chung l pH : 1. 2. 3...... n = n !

Nu c 20 acid qun ta c con s peptid gm 19 ch s sau:2.432.902.008.176.640.000

Cu trc bc mt ca protein l yu t di truyn ht sc n nh. Mi t hp cth t sp xp acid amin khc nhau, ch cn mt acid amin no trong t hp khc ith tnh cht vt l, ho hc v sinh hc ca protein khc i rt xa.

Ta ly mt vi th d v cu trc bc mt ca protein

* Hng cu ca ngi c 600 - 640 acid amin. Khi th t ca vlin v acid

glutamic v tr th 6 v 7 i ch cho nhau lm cho hng cu t hnh trn binthnh hnh li lim (m hng cu hnh li lim l mt bnh di truyn v l nguyn


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nhn gy ra thoi ho ging).

* Phn t insulin l mt polypetid bao gm 5 1 acid amin chui A c 2 1 gcacd quan v chui B c 30 gc acid amin. Hai chui ni vi nhau bi 2 cu dsulfit:cu th nht gia gc cystein v tr 20 ca chui A v v tr 19 ca chui B; cu th

hai gia gc cystein vi t th 7 ca c 2 chui. cc ng vt khc nhau, chng ch khc nhau acid amin th 8, 9, 10.

8 9 10

B Alanin Serin Valin

Ln Treonin Serin Isoleucin

Cu Alanin Glycin Valin

* Ocytocin v vasopressin l hai loi hormon ca thu sau tuyn yn, chng u

c 9 acid amin, nhng sp xp ch khc nhau v tr s 3 v s 8.

Ocytocin c tc dng lm tng co bp ctrn t cung, cn vasopressin lm tnghuyt p ng mch, chng li tiu.

Vic pht hin ra cu trc bc mt ca cc protein l mt thnh tu rt ln trongho hc protein. N l cu trc quan trng nht, quyt nh hnh dng v hot tnh sinhhc ca cc protein khc nhau. Tnh mun hnh mun v ca protein trc ht l ctnh sinh hc ph thuc vo cu trc bc mt. Hin tng c trng sinh hc chnh ls khc nhau v cu trc v chc nng ca protein v l nguyn do ca tnh c trng,c th ca sinh vt, tc l khc nhau v loi, ging, tng c th v cc b phn trongtng c th

Qu trnh di truyn sinh vt chnh l hin tng truyn t li cho i sau cutrc bc mt ca protein c th ca loi ging.

Cu trc ca proten c m ho qua thit k m di truyn acid nucleic.

2.2.2.2. Cu trc bc hai ca protem - lin kt hydrogen

Lin kt hydrogen c pht hin nhphng php quang ph (phn hng ngoib mch ny hp ph).

Lin kt hydrogen thng xut hin trong nhng h p cht c hin tng phncc r rt trong phn t.

V dnc, do s phn cc m nguyn t oxy c in tch m d v hydroc in tch dng d. Khi hai phn t nc nm gn nhau n mt mc nht nh,gia cc in tch d i du ca chng s xy ra lin kt ph, gi l lin kt


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hydrogen. c tnh ca lin kt ny l khng cnh m c tnh linh ng, lc lin ktca n yu gp 10 - 12 ln so vi lin kt ng ho tr.

Trn mt phng c th biu din lin kt hydrogen do cc nhm - Co - NH - cahai chui petid nh sau:

Da vo s liu v kch thc phn t v gc to nn bi cc gc acid amin,ngi ta cho rng chui peptid trong protein t nhin thng cun theo hnh xon c.C nhiu kiu xon c nh, , ... Nhng loi xon c kiu (alfa) c nhiungi cho l gn chn l nht. c im ca loi ny l mch hydrogen gia cc linkt peptid chim sng, to cho xon c thn nh nht v nhng nguyn t sinhlin kt peptid - CO - NH - u nm trong mt mt phng.

- Nhiu protein ca c, mu, cc m mm cha cc on xon chui peptid cunli theo hnh l xo, to thnh nhng bc xon. Bc xon cha 3,7 gc acid amin.

- Dng gp np l cu trc bc hai c trng cho nhiu protein dng si nhkeratin lng, sng, mng.

Lin kt hydrogen gi v tr c bit quan trng trong tnh cng, linh hot cacc phn t sinh hc, ca protein cng nh m bo. Chnh cu trc bc hai lm cho

phn t protein mm do c thn hi c.


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Mc d cu trc protein c cng c rt nhiu bng lin kt hydrogen, nhngcc th nghim v ho l cho thy rng cu to vng xon c trong dung dch khng

bn v s b bung ra thnh chui ni. iu ny a n vic ra cu trc bc ba vinhiu loi lin kt c tc dng n nh ng k nhng mi xen protein dng cu.

2.2.2.3. Cu trc bc ba ca protein - lin kt disulfid (-S- S-)Cu trc bc ba l dng khng gian ca cu trc bc hai, lm cho phn t protein

c hnh dng gn hn trong khng gian. S thu gn nh vy gip cho phn t proteinn nh trong mi trng sng.

C sca cu trc bc ba l lin kt disulfid. Lin kt c hnh thnh t haiphn t cystein nm xa nhau trn mch peptid nhng gn nhau trong cu trc khnggian do s cun li ca mch oevtid. y l lin kt ng ho tr nn rt bn vng.

Cu trc bc 3 to nn trung tm hot ng ca phn ln cc loi enzym. Sthay i cu trc bc ba dn n s thay i hng xc tc ca enzym hoc mt kh

nng xc tc hon ton.

Ngoi trn kt disulfit, cu trc bc ba cn c n nh (bn vng) nhmt slin kt khc nh:

- Lin kt hydro: hen. kt ny xut hin khi gia hai nhm tch in m cnguyn t hydro.

Lin kt tn: lin kt ny hnh thnh gia hai con tri du ca hai gc acid aminnm xa nhau theo th t trong chui peptid, nhng gn nhau trong cu trc khng

gian. V d: gia COO-

ca acid glutamic vi NH3+

ca lysin. Loi lin kt ny nmri rc trong phn t do c mt s gc acid amin c hai nhm COOH v NH2.


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V d v cu trc bc 3 nh: Phn tinsulin l mt polypeptid bao gm 51 acidamin chui A c 21 gc acid amin vchui B c 30 gc acid amin. Hai chuini vi nhau bi 2 cu disulfid: cu thnht gia gc cystein v tr 20 ca chuiA v v tr 19 ca chui B; cu th haigia gc cystein v tr th 7 ca c 2chui. Trong chui A cn c mt cudisulfit gia 2 gc cystein v tr th 6 v11 . Insulin l hon non tuyn tu tham giaiu ho hm lng ng trong mu.Khi thiu insulin, hm lng ng trong

mu tng cao, dn ti hin tng bnh ing Insulin c tc dng hng huyt

bng cch xc tin qu trnh tng hpglycogen d tr t glucose.


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- Lc hp dn Van dt Vals: l lc ht gia hai cht hoc hai nhm ho hc nmcnh nhau khong cch 1 - 2 ln ng knh phn t.

Lc lin kt ca cc nhm k nc, nhng nhm khng phn cc (- CH2; -CH3)trong vang, leucin, isoleucin, phenylalanin... Nc trong t bo y cc gc ny li vi

nhau, gia chng xy ra cc lc ht tng h v to thnh cc bi k nc trong phnt protein.

Do c cu trc bc ba m cc protein c c hnh th c trng . v .ph hpvi chc nng ca chng. cc protein chc nng nh enzym v cc khng th,

protein ca h thng ng mu... thng qua cu trc bc ba m hnh thnh c cctrung tm hot ng l ni thc hin cc chc nng ca protein.

S duy t hnh dng gip protein trng thi nguyn vn, tc l cc hot tnhsinh hc c duy tr. Mi bin i ca hnh dng ko theo s bin i ca hot tnh.

men cu trc (Structural domain) c nghin cu t 1976, n nay ngi tacho rng s hnh thnh men rt ph bin cc chui peptid tng i di.

men cu trc c thc nh ngha l nhng b phn, nhng khu vc trongmt phn t protein c cun gp trong khng gian ging nh mt phn t proteinnh hon chnh v thng l nhng ni thc hin chc nng lin kt, chc nng lprp ca phn t protein trong hot ng chc nng ca n. Trong nhiu protein, men gn lin vi chc nng kt hp c hiu v nhiu enzym c cu to t cc men th trung tm hot ng li c b tr bin gii ca hai hay nhiu men.

S thnh thnh cc men trong phn t protein to ra kh nng tng tc linhhot gia cc i phn t, kh nng cng, dch chuyn tng ng gia nhng b

phn trong qu trnh thc hin chc nng sinh hc. - nhng protein ngun gc khcnhau, nhng c chc nng tng t th cc men c cu trc tng i ging nhau.

2.2.2.4. Cu trc bc bn ca protein

L mt trng thi t hp hnh thnh t nhiu tiu phn protein c cu trc bcba hon chnh.

Mt s protein c xu hng kt hp li vi nhau thnh nhng phc hp, thnhnhng i phn t, khng ko theo s bin i v hot tnh sinh hc.

Rt nhiu trng hp protein phi t hp li mi c hot tnh sinh hc. Trongnhng trng hp ny, cu trc bc bn l iu kin hnh thnh nn tnh nng mica protein.

V d v cu trc bc bn:

- Hemoglobin (Huyt sc t) gm 4 tiu phn protein: hai tiu phn v hai tiu

phn .Nu 4 tiu phn tch ri nhau th mi tiu phn khng th vn chuyn cmt phn t O2' Khi kt hp li thnh trng thi tetramer to thnh mt khi khng


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gian c

th gn nh hnh t din th mi c kh nng kt hp v vn chuyn kh oxy.Mt phn t hemoglobin (Ht) vn chuyn c 4 phn t oxy.

- Enzym glycogen phosphorylase ( c, gan) xc tc qu trnh phn giiglycogen thnh glucose.

+ trng thi khng hot ng enzym ny dng "b" (dng hai dimer tch rinhau).

+ trng thi hot ng (khi c tn hiu cn ng) hai dimer t hp li thnhtetramer (dng "a").

Khi nhu cu gii phng glucose gim, tetramer li tch thnh hai dimer, enzymtrli dng khng hot ng.

Tu theo protein m s lng monomer c th thay i t 2,4,6,8 l ph bin, cbit c th ln ti trn 50 monomer.

S hnh thnh cu trc bc bn to iu kin cho qu trnh iu tit sinh hcthm tinh vi, chnh xc.

2.3. CC C TNH CA PROTEIN

2.3.1 Trng lng phn tNgay phn nh ngha nhn mnh: c im ca protein l trng lng phn

t rt cao. Nhng nghin cu khc nhau gn y cho thy trng lng phn t thcca protein nm trong khong 6.000 - 12.000. Tuy nhin, trong iu kin t nhin

phn t protein thng lin kt vi nhau to thnh nhng phn (gi l mixen) c trnglng phn t rt ln t ti hng triu.

Trng lng phn t ca mt s loi protein:

Albumin sa 17.400

Albumin trng 44.000


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Globulin huyt thanh 310.000

Hemoglobin ngi 68.000

Enzym pepsin 45.000

Enzym ribonuclease 12.700

Siu vi khun cm 322.000.000C th ni: protein l "i phn t" bi v thnh phn ca n gm hng trm,

hng nghn nguyn t lin kt vi nhau ch yu bng lin kt ng ho tr.

2. 3.2. Trng thi keo

u th k XIX cc nh khoa hc bn ci kh lu v trng thi nguyn sinh cht(protoplasma) sinh th, bi v c nhng mu thun:

* C th nguyn sinh cht l trng thi lng. Bi v ti sao cc phn ng hohc tin hnh trong c th vi tc nhanh? iu ny c trng cho mi trng

lng.* Nhng ti sao c th li c kh nng gi nhng hnh th c bit ca mnh?

Tnh cht ny ch c th rn.

Mi mu thun c gii thch khi ngi ta pht hin ra trng thi keo caprotein.

Trng thi keo ca protein th hin cc c im sau:

- Gy p sut thm thu rt thp 30 - 40mm Hg (0,03 tm)

- Kh nng khuch tn t

- nht cao.

nht phn nh cu trc (hnh dng, kch thc) ca phn t - Kch thccng ln nht cng cao.

Nu ly nht ca nc lm chun l 1 th:

nht ca albumin trng g l 1,2 - 1,57

nht ca gelatin l 4,54 - 14,2

- Kh nng hp ph cc cht khc kh cao

- Kh nng khuch tn nh sng (hin tng Tindal) tc l khi cho 1 tia sngqua dung dch protein trn nn c ca dung dch ta nhn r c nhng tia .

2.3.3. Lng tnh v im ngin

2.3.3.1. Tnh tng tnh

Trong dung dch nc, phn t protein c kh nng tc ng nh mt acid,hoc mt kim yu, bi v trong phn t protein c cc nhm nh chc qun vcarboxyl c kh nng phn ly.

Phn t protein mang cin tch dng v in tch m nh vy gi l amphiol.


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Kh nng phn ly ca nhm quan v nhm carboxyl thay i ph thuc vo iukin mi trng, c th l pa. Khi pH thp, ion H+ mi trng nhiu th nhmCOOH gim s phn ly. Ngc li, nu mi trng kim, tc ton OH nhiu th NH2 s

bt phn ly.

V s lng nhm quan v carboxyl trong phn t protein khc nhau, cho nnnu s lng nhm COOH tri hn nhm NH2 th sau khi phn ly, in tch tng sca ht keo protein s c du m v ngc li.

Khi cho dng in mt chiu i qua mi trng th nhng ht keo ni trn sdi chuyn vin cc tng ng.

Tui lng in tch, tu trng lng phn t m tc di chuyn ca mi

loi protein khc nhau. l csca phng php in di trn giy.

2.3.3.2.im ngin

Nh chng ta bit, kh nng phn ly ca cc nhm quan v carboxyl chu schi phi ca phn ng mi trng, do bng cch thm acid hoc kim ta c thtti mt tr s pa, m s phn ly ca NH2 v coh bng nhau. pH ny ngi tagi l im ng in ca protein (k hiu l pI).

Ti im ng in cc ht keo c in tch bng O

Mt vi v d vim ng in ca protein:

Casein 4,7 Zein ng 6,2

Albumin 4,8 Miosin c 5,0

Globulin 5,4 Histon 8,5

C th da vo im ng in tch ring tng loi protein.

2.3.4.c tnh ho tan

Trng thi keo ca protein bn vng l nhc lp v thu ho bao bc bn ngoicc ht keo v cc in tch lm cho cc phn t protein ngn cch v khng dnh vo


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nhau. C nhiu yu tnh hng n tnh tan ca protein.

- nh hng ca pH

tan ca protein thp nht pH = pI ca n, tan ca protein tng ln khi pHnm xa i v khi pH = pI th phn t protein khng tch in nn chng khng c lc

ytnh in v d bng kt. Khi pH khc i th cc phn t protein tch in cng

du v y nhau cho nn khng bng kt, do tan tng ln.

- nh hng ca nng mui

Mui trung tnh nng thp lm tng tan ca nhiu loi protein. Khi tngnng mui ti mt gii hn nht nh th tan ca protein gim xung v nunng mui tip tc tng ln th protein c thng kt hon ton. Tnh cht ny

c ng dng tch cc loi protein theo phng php dim tch.- nh hng ca dung mi

Khi cho cc dung mi nh cn, e, benzen, aceton, cloroform... vo dung dchprotein th tan ca protein b gim v c th dn n ng kt do ph vlp v thyha.

- nh hng ca nhit

Trong khong nhit t 0 n 450C, tan ca protein tng khi nhit tng.

Cn khong nhit t 45 - 750

C a s protein mt tnh keo v c th b bin tnh(tr protein ca mt s loi sinh vt chu nhit).

2.3.5. Hin tng sa lng v bin tnh

Trng thi keo ca protein bn vng l nhs cn bng cc in tch v lp vthu ho. Khi trng thi ny b ph vbi cc yu t nh nhit cao, mui cc kimloi nng, dung mi hu c... th protein rt d b sa lng. Hin tng sa lng proteinc th thun nghch, tc l n c th trli trng thi ban u khi tc ng ca cc yut trn cha tht su sc. Tuy nhin, nu s tc ng mnh v lu s lm cho

protein b bin tnh. Khi b bin tnh protein s mt hot tnh sinh hc ca n.

2.4. PHN LOI PROTEIN

Cha c mt cch phn loi no phn nh tt nht bn cht v s lng ca nhmcht hu cquan trng ny.

Ngy nay, ngi ta c th phn loi protein theo cc sc sau y:

2.4.1. Da vo hnh dng ca protein

Da v hnh dng ca protein ngi ta tm phn hnh th protein thnh hai dng:dng cu v dng si.

2.4.1.1. Protein dng cu


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Protein dng cu l loi protein m phn t ca n thng cun li thnh vng,thnh bi, gn trn hoc bu dc.

in hnh ca dng protein ny l: Albumin, globulin trong, sa, huyt thanh,enzym pepsin, dch v. . . Loi ny thng ho tan trong nc .

Tuy gi l dng cu, nhng nu xt t lng knh ca chng ta thy tng ngl/3 (glubulin sa) 1/7,5 (ca globulin huyt thanh) 1/20 (ca zein ng). V vy lnhng cu hnh a phnh th ng hn.

2.4.1.2. Protein dng si

Protein loi ny vi mch peptid khng cun r, ch gp np dc chui, nn nichung c chiu di r rt.

in hnh ca dng protein ny l: fibroin ttm, miosin si c, colagen v

elastin da v gn. c tnh ca loi ny l khng ho tan trong nc v c kh nngco gin mt chng mc no , v nhng np gp ca chui peptid c th bin itheo trc di.

V d protein dng si nha v Keratin

4.2. Da vo chc nng ca protein

- Protein co gin c(actin, miosin ca c)

- Protein d tr (Femtin gan d tr st)

- Protein men trao i cht (Pepsin d dy thu phn protein)

- Protein hormon (Insulin, vasopressin)


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- Protein khng th

- Protein c t

- Protein c chc nng c bit (Hemoglobin mang oxygen, rodopsin trongqu trnh th gic, virus).

2.4.3. Da vo gi trdinh dng ca protein

Cc nh sinh vt hc li da vo gi tr dinh dng hay tm quan trng caprotein i vi s sng phn loi protein. Theo quan im ny protein chia lm 2loi:

2.4.3.1. Protein c gi tr dinh dng khng hon ton

l nhng protein cha khng y hoc y nhng t l khng cn icc acid amin thit yu. Loi ny thng l cc protein thc vt.

2.4.3.2. Protein c gi tr dinh dng hon ton

l nhng protein cha y vi t l cn i cc acid amin thit yu. Loiny thng l cc protein ng vt nh trng, sa, tht...

2.4.4. Da vo cu to ho hc ca protein

Theo quan im ca Hp-pe-zai-l (Hoppe - Seyler) v Drecxen ra gia thk XIX protein chia lm 2 lp ln:

- Lp protein n gin hay ng nht

- Lp protein phc tp hay cn gi l proteid

2.4.4.1 .Lp protem n gin

y l nhng protein khi b thu phn hon ton s cho ta cc acid amin.

Cc i din chnh ca lp ny l:

*Albumin v globulin

L hai loi protein dng cu rt ph bin trong cu to ca m bo ng vt v

thc vt Thnh phn gm hon ton cc acid amin trong t l acid amin c tnh acidkh cao.

Albumin l protein n gin ph bin nht. N tm thy trong mu, dch t bo,dch tu sng. Albumin ho tan trong nc v cc dung dch mui. Albumin ng khiun nhng cc nhit khc nhau: albumin trng ng nhit 560C, albuminhuyt thanh 670C, albumin sa 720C.

Albumin ca ng vt (nh albumin huyt thanh ca mu) khi thu phn cho 19acid amin v thnh phn cc acid amin t khc nhau cc ng vt (tr vt). Albuminthng cha s lng ln cc acid amin sau: leucin, acid glutamic, acid aspartic, lysin, cn cc acid amin nh methionin, tryptophan, glycocol... s lng t hn.


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Trng lng phn t ca albumin khong 35.000 - 70.000, im ng in nmtrong khong pH 4,6-4,7.

Albumin thng to thnh cc phc cht vi lipid, acid bo, Acid amin, khngth...nn c quan im cho rng n gi vai tr tch cc trong trao i vt cht.

Globulin hu nh nm cng vi albumin v rt ph bin trong t nhin. N cnhiu trong mu ng vt, trong cc cquan, t bo, trong cc dch lng ca cth.

Globulin kh tan hoc hon ton khng tan trong nc, nhng tan trong cc dungdch ca mui trung tnh, kim, acid.

Globulin cha khong 14-19 acid amin quan trng nh: leucin, vang, ly sin, acidglutamic, sm, treo nin.

Trng lng phn t ca globulin khong 90.000 - 1.500.000 hoc ln hn, im

ng in nm trong khong pH 5,0-7,5.Globulin gm , , . Chnh y - globulin l ngun gc khng th trong cth.

T l AIG trong huyt thanh ng vt thng mc kh n nh v thay i rkhi cth mc bnh. iu c ngha rt ln trong chn on v tnh trng sc khoca ng vt ng thi hm lng globulin huyt thanh cn phn nh tnh khngca cth.

*Hisum v protamin

Histon v protamin l hai loi protein c tnh kim r rt v trong thnh phn cachng t 30 - 80% acid amin kim tnh nh ly sin v arginin.

Histon l protein c cu to n gin. N cha s lng aci quan t hn so vialbumin v globulin. Trong histon khng c cystein, cystin, tryptophan, m ch yu larginin v ly sin (20-30%). Histon c Koccel tm thy trong nhn t bo, trongthnh phn ca nucleoprotein v cc protein phc tp khc. im ng in ca histonnm trong khong pH 9,0-11,0.

Protamin c Miser v Koccel tm thy trong thnh phn ca nucleoprotein ca

t bo sinh dc c. Sau cn pht hin lch, tuyn diu v cc c quan khc.Protamin c trng lng phn t thp (2.000-8.000), thnh phn cha t acid amin (6-8), trong ch yu l acid amin diamin (ti 80% arginin). i din protamin cnghin cu nhiu l xan min- l mt chui polypeptid kt thc bi nhm quan cathon. Khi un protamin khng ng v khng sa lng, n ch sa lng bi mui kimloi nng. im ng in ca protamin nm trong khong pH t 10,5 n 12,0.

* Glutelin v prolamin

l nhng protein thc vt c trong cht do ca la, go, ng.

- Prolamin c nhiu cc ht ho tho. c im ca prolamin l tnh ho tantrong cn 70% v khng tan trong nc. Khi thu phn prolamin thng cho nhiu


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thon v acid glutamic (43%).

My i din ca prolamin c nghin cu k nht l gliadin ca la m,gordein ca i mch, zein ca ng, avenin ca yn mch, n~enin ca go... Trongthnh phn my protein ny t l lysin rt thp (zein hu nh khng c).

- Glutelin c cc loi ht khc nhau, hm lng t t 1 - 3%, c tnh caglutelin l ch ho tan trong kim long 0,2 - 2,0%.

* Cc proteinoit

y l nhm protein ca m chng c thng vt nh xng, gn, da,sng, lng, mng... Chng c gi l "ging protein" v tuy c cu to t cc acidamin, nhng chng mt tnh keo quan trng l tnh ho tan. y l nhng git'.in bintnh, c dng si gp nm song song thnh b.

Chc nng: bo v cgii i vi m bo.Cc i din ca nhm ny l:

Colagen (v procolagen) l protein ca si m lin kt gn, da, di da...N khng ho tan trong nc, nhng khi tc ng lu ca nhit s trthnh dng hotan l gelatin. Keo dn chda tru chnh l colagen.

Hm lng glycin ca colagen kh cao (25%), nhng v nhiu acid amin khngthay thc th li thiu.

Colagen tng t l vi tui tc.- Elastin: phn b cc m co gin v chu lc nh gn, dy chng cc khp

xng.

bn chc ca elastin cao hn colagen v hon ton khng th trng nhcolagen.

- Keratin (ting Hy Lp keras - sng)

L cht ch yu ca tc, lng, sng, mng, lp thng b... hon ton khng tan,

k c trong dung dch acid, kim. Khi thu phn cho nhiu cystin (7 - 12%) v acidglutamic (4 - 17%).

Trng lng phn t khong 2 triu.

Fibroin: protein ca tla do tm nh ra.

Si t do nhiu si fibroin lin kt thnh b, gn bi h sericin ca tm hocnhn nh ra (m tvi nc nng nhm ty h ny).

2.4.4.2. Lp protein phc tp

Lp protein phc tp, hoc protein khng ng nht, l nhng cht bao gm 2thnh phn:


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- Phn protein n gin

- Phn ph hay cn gi l nhm ghp.

Nhm ghp c ngun gc khc nhau. S lin kt gia chng vi phn proteinn gin c bn vng khng u, c cht lin kt cht ch, c cht lin kt hi ht,

d tch trong qu trnh. phn tch nghin cu.Da vo bn cht ca nhm ghp, ngy nay ngi ta chia protein phc tp thnh

5 loi chnh.

- Glucoprotein

- Phosphoprotein

- Chromoprotein

- Lipoprtein

- Nucleoprotein

2.5. CC LOI PROTEIN PHC TP

Nh trn trnh by, protein phc tp l loi protein khi thu phn ngoi phnprotein n gin, cn c thm nhm ghp. Ph thuc vo nhm ghp m protein phctp c tn gi tng ng. Sau y ta xt tng loi:

2.5.1. Glucoprotein

Nhm ghp ca loi ny l nhng dn xut ca glucid, c thdi dng quanho nh glucosamin, galactosamin, manosamin chng lin kt vi phn protein bngnhng lin kt ng ho tr.

Glucoprotein c vai tr quan trng trong cu to ca nhiu loi m chng vbo v v d trong sn xng, trong cu to ca khng nguyn v khng th.

Glucoprotein hay gp trong cthng vt thng chia lm hai loi:

* Mucin: l nhng cht thng c nhiu trong nc bt, nc mt, dch nhn baokhp, dch m lin kt, dch nang bo, nim dch. Mucin nim mc d dy, rut, niuqun c tc dng bo v cgii v ho hc. Nhm ghp ca mucin l hp cht acid

Tc dng ca mucin l lm gim cc ma st chc nhm bo v cc cquan


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(nh nim mc ming, thc qun, d dy...).

* Mucoid: c nhiu m bo nh:

- sn c chondromucoid

- xng c osteomucoid

- lng trng trng c ovomucoid

v nhiu cht na gn, gic mc mt, thu tinh th...

Ngoi ra mt s glucoprotein c chc nng sinh hc quan trng nh hon non kchthch tuyn sinh dc: FSH, prolanA cha 20% glucid, LH cha hn 20% glucid.

Trn mng t bo c nhng cu trc min dch c th ca mi cth sinh vt cbn cht l glucoproteid. 1

2.5.2. PhosphoproteinL protein phc tp khi thu phn cho cc acid amin v acid phosphoric (H3PO4)

cc aci phosphoric ni vi protein bng mch este qua nhm OH ca serin hoctreonin trong phn t protein.

Loi protein ny thng c tnh toan v ng vai tr quan trng trong dinhdng ca ng vt non.

i din in hnh c th k l:

- Casein: l protein ch yu ca sa.

- Ovovitelin v vinh lng trng

- Ictulin trng c.

Thnh phn ca cc loi ny cha y 20 loi acid amin v rt cn i nn tl hp th kh cao v l nhng loi thc n c gi tr dinh dng c bit.

2.5.3. Chromoprotein (chHy Lp: Chroma - mu sc)

y l nhng protein mang mu sc nh hemoglobin trong mu c mu ,clorofil trong l cy c mu xanh...

Sdc mu v nhm ghp ca chromprotein thng l nhng cu trc phc

tp, to nn cc mu sc khc nhau do c cha mt hay nhiu nguyn t kim loi nhFe, Mg, Cu...


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Phn nhiu chromoprotein tham gia vo cc qu trnh trao i kh

V d: Hemoglobin vn chuyn O2 v CO2 gia phi v m bo

Mioglobin d tr O2 cho c.

Catalase phn gii H2O2 thanh O2 V H2O.

Mt si din chnh ca nhm ny l:

2.5.3.1. Hemoglobm(cn gi l huyt sc t, k hiu l Hb)

Hemoglobin c Huyn-ne-phan tm ra 1840. l loi protein c nhiu tronghng cu, thnh phn ca n gm:

- Phn protein n gin l globin chim 94% trng lng Hb

- Phn nhm ghp l nhn Hm chim 6%

Trng lng phn t ca Hb gn 67.000. Chc nng ca Hb l vn chuyn khgia phi v m bo

* Cu to

Hemoglobin c cu to t protein - globin v nhm ghp l hm. Cu to cahm c Nenski v Fisher tin ra.

Cu trc hem ca hemoglobin: Hem l lin kt, m phn t ca n gm nguynt t 2 v 4 vng pyrol. Bn vng pyrol ni vi nhau bng dy metyl (= CH- ) -

l ct porfin. Ct porfm gn vi 2 gc Vinyl (- CH = CH2) 4 gc metyl (- CH3) v 2gc acid ropionic to thnh dng protoporfl. Protoporfin lin kt vi st 2 chnh lnhn hm (hnh trn).


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Ngoi ho tr chnh ra, st cn ni vi 2 nguyn t Nitbng hai lin kt ph(biu din bng ng chm).

Mi phn t hemoglobin c 4 tiu phn protein: hai tiu phn v 2 tiu phn .Mi tiu phn gn vi mt hm. Nh vy phn t hemoglobin c 4 hem. Cch lin kt

gia hm v globin cha c xc nh r. Theo nhiu ti liu ca nhiu tc gi thlin kt ny xut hin gia st v nh ca nhn imidazol ca phn t histidin trongglobin.

* Tnh cht ca hemoglobin v cc dn xut ca n

Khi tc ng vi acid hoc kim, hm - st hai s thnh hm - st ba: Fe2+Fe3+ v c tn l hematin.

Chc nng sinh l ca hemoglobin th hin tnh lin kt vi cc loi kh nhO2, CO, NO... Tu p lc ring ca chng, s lin kt ny thc hin qua mch ph ca

nguyn t st vi globin nn khng bn v cc kh s dy nhau tu p sut mi loi.C my lin kt v dn sut ca hemoglobin l:

- Oxyhemoglobin Hb.O2 (vi oxy)

- Carboxyhemoglobin Hb.Co (vi oxyt carbon)

- Met-hemoglobin Hb.OH (khi Hb b oxy ho thnh dng ferric)

+ t bo phi: p sut ring ca oxy cao nn n d lin kt vi hm. y llin kt h, nguyn t st 2 khng thay i ho tr, nn khng phi l phn ng oxy -ho. Hb.O2 to cho mu c mu ti.

Khi ti mch qun cc m, p sut ring ca oxy thp nn kh ny thot ra vc dng vo cc nhu cu sinh ho hc.

+ m bo: CO2 (khong 20% tng s CO2 thi ra) s lin kt vi globin quanhm quan cui cng thnh carboxyhemoglobin.

Phn ch yu (gn 80%) CO2 lin kt vi kim ca huyt tng v hng cuthnh nhng bicarbonat nh NaHCO3, KHCO3 ri mi n phi, chuyn sang dngacid carbonic v thi theo hi th.

Khi trong khng kh c gn 1% th tch Co th gn 95% Hb ho thnh Hb.Co vvy vic ly O2 b trngi lm cho cth b ngt. Nu tng p sut ring ca oxy (chothoxy) th Co by khi Hb v cha c ngt.

Khi Hb b tc ng bi cht oxy ho nh femxyanua kim (K3[Fe (CN~ oxyt noth Hb Hb.OH c st ba.


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Nu HbOH sinh nhiu, chc nng h hp ca mu s b trngi. lu Hb.OHb phn ly tr Hb v dng c.

l csgii c HCN (cht ny bin Hb thnh cyanomet - hemoglobin) bng

xanh metylen (chuyn Hb.CN kh phn ly sang dng Hb.OH d phn ly).

Tng quan gia hemoglobin v cc dn sut ca n nh oxyhemoglobin,carboxyhemoglobin v methemoglobin c th biu din nh sau:

2.5.3.2. Mioglobin

Mioglobin l sc t ca c, cng c nhm ghp l hm cha st nh hemoglobin.

Nhm globin ca mioglobin c trng theo loi, trng lng phn t trung bnh17.000.

Khc vi hemoglobin, nhm ghp ca mioglobin ch cha mt nguyn t st, vvy m phn t protein ca n ch c mt nhn hm. Tuy c cu to n gin hnhemoglobin nhng i lc ca n i vi oxy mnh hn hemoglobin.

cnht l c tim, vai tr d tr oxy ca mioglobin (di dng oxymioglobin)rt quan trng: hin tng ny m bo cho chot ng khi bi O2 trong trnghp s np O2 b gin on tm thi (nn th, ngp ln...)

V d: ngi, cth d tr 2450ml O2 trong 354ml c trong mioglobin.

Lng d tr ny rt ln nhng ng vt sng nc nh Hi Cu.Mu ca cdo mioglobin to nn.

2.5.4. Lipoprotein

Lipoprotein l lin kt gm nhiu phc cht ca protein v lipid. bn ca milin kt protein - lipid khng cnh.

Lipoprotein c tnh ho tan trong nc, nhng khng ho tan trong cc dung mihu c(nhe, cloroform...)

Chc nng sinh hc ca nhm ny gm nhiu mt, nhng quan trng nht lchc nng cu to vch t bo v cu to cc tiu kh quan t bo nh ty lp th.


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Ngi ta cho rng tnh bn thm v tnh hp thc hiu ca t bo l do lp vlipoprotein quyt nh.

Trong mu v m bo c my cht hpoprotein quan trng nh:

Tromboplastin (gip cho qu trnh ng mu)

Lipoprotein huyt thanh (c phn protein l globin)

- Rodopsin vng mc mt l loi lipoprotein tham gia vo hot ng th gic.

- Ni c t ca nhiu vi khun cng c cu trc l lipoprotein. V d: ni c tca vi khun lao, brucena...

2.5.5. Nucleoprotein

y l loi h p cht hu c c mt vai tr cc k quan trng trong sinh hc.Ngi ta tm thy chng nhng sinh vt n gin nht (nh nguyn sinh ng vt)

n nhng ng vt cao ng nht (nh loi c v). Ngay cc siu vi khun (vus)cng c thnh phn ch yu l cc nucleoprotein. Qua cc nghin cu v di truynhc, t chc hc, sinh ho hc ngi ta c th ni chc chn rng: Nucleoprotein cquan h trc tip n cc qu trnh sng ch yu ca mi sinh vt nh tnh di truyn,

bin d, kh nng tng hp protein.

Nucleoprotein gm 2 thnh phn ch yu:

- Protein n gin (thng l protein kim tnh nh protamin v histon) - Nhm

ghp l acid nucleic.Do tm quan trng ca lp nucleoprotein i vi s sng nn chng ta s nghin

cu t m chng mt chng ring.


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Chng 3

NUCLEOPROTEIN V ACID NUCLEIC

3.1. I CNG V NUCLEOPROTEINNucleoprotein l protein phc tp gm hai thnh phn ch yu l:

- Phn protein n gin thng l protein kim tnh nh protamin v histon.

- Phn nhm ghp l acid nucleic

Phn protein n gin ta xt chng 2, y ch yu ta nghin cu v acidnucleic

S thu phn nucleoprotein c th biu hin nh sau:

Nucleoprotein c pht hin ln u tin nm 1869 o Mischer trong cc t bom.

Cng lao cc nh bc hc: Le vin, Chagaff, Devison,Watson, Cch... lm sngt thnh phn cu to ca acid nucleic.

3.2. THNH PHN V CU TO ACID NUCLEIC

Acid nucleic khi thu phn hon ton th phn thnh ba loi hp cht:

- Cc ng pentose: D-ribose v D-desoxyribose- Cc baz: phun (adenin, guanin) v pyrimidin (Cytosin, uracin, thi min)


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- Gc acid phosphonc (H3PO4)

3.2.1.ng pentose

Pentose gm D- ribose v D - desoxynbose. Hai cht ny c trong acid nucleicdi dng Phu ran :

Ribose c trong acid ribonucleic (ARN)Desoxyribose c trong acid desoxyribonucleic (ADN) 3.2.2. Cc baz

3.2.2.1. Bazpynmidin


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3.2.2.2. Bazpurin

3.2.3. Nucleosid

Nucleosid l kt qu ca s kt hp bng lin kt osid gia mt baz(phn hocpyrimidin) v mt ng pentose vi s loi ra mt phn t nc.

S lin kt ny thng qua mch glyosid v tr 9 ca phn hoc v tr th 3 ca


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Acid phosphoric thng c gn vo v tr th 3 hoc th 5 ca ng pentose.

Loi gn v tr th 3 thng dng lin kt, cn v tr th 5 thng dng tdo.

Sau y l tn gi ca cc nucleotid

Baz Nucleotid trong ARN Nucleotid trong ADN K hiu

Adenin Acid adenilic Acid desoxyadenilic A

Guanin Acid guanidilic Acid desoxyguanidilic G

Urasin Acid uridilic Acid desoxyuridilic U

Cytosin Acid cytidilic Acid desoxycytidilic C

Thimin Acid thimidilic Acid desoxythimidilic T

Cch lin kt ca cc mnonucleotid nh sau:

Cc nucleotid c th phosphoryl-ho to thnh di-, tri- phosphonucleotid.Dng ny thng trng thi t do trong cc m bo v cquan ca sinh vt v lmnhim v d tr nng lng do thu c trong qu trnh oxy ho cung cp cho cchot ng sng - cu trc ca chng nh sau:


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Nh vy ta thy trong chui polynucleotid, ng v phosphat lin kt vi nhau,cn gc kim nm t do, chnh s lng v th t phn b ca cc gc kim trongchui nolvnucleotit quyt nh tnh c trng sinh hc ca phn t acid nucleic.

3.3. PHN LOI ACID NUCLEIC

3.3.1. Csphn loi acid nucleic

Da vo s c mt ca ng ribose v desoxyribose m ngi ta chia acidnucleic ra lm hai lp.

- Acid ribonucleic (ARN)- Acid desoxyribonucleic (ADN)

Khi nghin cu v hai lp ARN v ADN ngi ta thy chng c mt simkhc bit nh sau:

ARN- Ch yu t bo cht- Trng lng phn t 2 - 3.104 - 6- cu to Chui n- Cha cc gc kim

Adenin (A)Guanin (G)Cytosin (C)Uracin (U)

- ng: Ribose- Chc nng sinh hc: trc tip tham gia

qu trnh tng hp protein.

ADN- Ch yu nhn t bo- Trng lng phn t: 1 - 2.106 8 - cu

to Chui kp- Cha cc gc kimAdenin (A)Guanin (G)Cytosin (C)Thi min (T)ng DesoxyriboseChc nng sinh hc: mang bn mt m

di truyn.

3.3.2. Tn gs ARN, ADN v lin kt ho hc


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Thnh phn ho hc ca ARN v ADN

Acid nucleic l cht trng hp ca mononucleotid. Phn t cha t 250 - 350nucleotid, c loi cha ti hng chc vn mononucleotid. Cc mononucleotid ni vinhau qua mch lin kt este gia hydroxyl ca carbon th 3 ca ng pentose viacid phosphoric ca mononuleotid bn cnh.

Acid nucleic ng vai tr trong di truyn ca ng v thc vt, n ng vai trch cht trong vic sinh tng hp protein.

Sau y chng ta si su nghin cu tng loi acid nucleic

3.3.3. Acid desoxyribonucleic (ADN)

Da vo s liu nghin cu hin tng nhiu x tia Rn-ghen v nhng s liuho l khc ngi ta i n kt lun rng ARN ch c cu trc chui n, cn ADN ccu trc chui kp (tc l do hai chui polynuleotid kt hp vi nhau theo kiu xonthng).

3.3.3.1. Quy lut bsung gc kim (qui lut Chagaff)

Khi phn tch nh tnh v nh lng ADN, Chagaff v cc cng s ca ng rt ra c kt lun sau:

- Hm lng tnh theo mt ca Adenin bng Thi min v Guanin bng Cytosin.

- T nhn xt (l) v (2) rt ra: tng s gc kim purin bng tng s gc kim


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pyrimidin.

A + G =T+C

V mt ho hc: hm lng nhm 6 - quan bng hm lng nhm 6 - xe ton.

T ba kt lun trn y Chagaff rt ra c qui lut b sung gc kim nh

sau: Trong iu kin sinh l bnh thng, hai chui nucleotid khi to ra xon kp slc n nh quanh nhau bng cc lc lin kt thng qua cc baz.

- Trong qu trnh lin kt cc bazca hai chui i din th mt chui s gpbazphun, chui kia s gp bazpyrimidin, cc bazlin kt vi nhau bng lin ktpydrogen, xut hin gia mt s v tr nht nh hai bazi xng, l v tr: Nlca phn vi Nl ca pyrimidin

C2 ca phn vi C2 ca pyrimidin

C6 ca phn vi C6 ca pyridin- Lin kt hydrogen mun xut hin phi tho mn hai iu kin:

+ C mt nguyn t hydro mang in tch (+) nm gia hai nguyn t mang intch (-).

+ Khong cch gia cc nguyn t mang in tch (-) nm trong khong 2 - 4 A0.

Tc l lin kt hydrogen ch c th xut hin gia cc c p baz chn lc ixng:

Adenin vi Thi min

Guanin vi Cvtosin

3.3.3.2. M hnh xon ADN

Da trn cc kt qu nghin cu cho php Crick v Watson ra cu to m hnhxon ADN vo nm 1953. M hnh ny c kim tra li trn c s nhng thnghim v tia Rn-ghen tinh vi hn bi Willkins v cng s ca ng. Chnh v cnhng ng gp nn Crick, Watson v Wilkins c gii thng Nobel 1962.

Theo Crick v Watson th ADN gm hai dy polynucleotid vi cc tri du nhaucun xon vi nhau xung quanh cng mt trc v to thnh vng xon i.


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Cc baznm trong vng xon thnh tng cp: pyrimidintrn mt dy v phn trn dy i xng v ngc li. Ch mts cp baznht nh ph hp: A i vi T; G i vi C (lin kthydrogen).

- Mi vng xon di 34 A

0

cha 10 cp gc kim- di mt cp gc kim l 3,4 A0.

- Bn knh vng xon 10A0

- Khong cch gia hai gc kim i xng l 3A0

3.3.3.3. Vai tr sinh hc ca ADN

Ngy nay trong sinh hc, c bit l trong sinh ho hc vvi sinh hc, ngi ta thu c nhiu ti liu chng t rng

ADN l cscu trc ca nhim sc th mang tnh thng tin ditruyn.

Ngi ta thy ADN trong t bo thn ln gp i ADN t bo mm. Th t sp xpca 4 gc kim trn

polynucleotid c tc dngnh mt m di truyn. Khicn ti to, mt dy

nucleotid, dy xon i tchra, lin kt hydro bt, midy nguyn thuc dngnh mt khun mu tng hp dy mi theo qui lut b sung gc kim.

3.3.4. Acid ribonucleic (ARN)

ARN c coi l cht tham gia trc tip vo cc phn ng tng hp protein. Loi

ny thng t p trung t bo cht (ch yu bo tng) mt s nhn. Chngthng dng chui bi ch ri.

ARN trong t bo chia lm 3 loi:

3.3.4.1. ARN thng tin: K hiu m - ARN im - messenger - ngi a tin) Trnglng phn t ca loi ny t 0,5 - 1,106, chim 3 - 4% tng s ARN, chng c tnghp nhn t bo trn khun ca phn t ADN y l khun th cp.

Nhim v ca m - ARN mang bn mt m di truyn hnh thnh nhn s chuiqua mng nhn ra t bo cht v tin ti v tr tng hp protein ribosom, n slm khun mu tng hp nn protein.

3.3.4.2. ARN vn chuyn: K hiu t - ARN (t - transfer - vn chuyn)


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t - ARN thng trng thi ho tan trong t bo, chim khong 15% tng sARN.

Trng lng phn t thp khong 2 - 3 vn, gm khong 60 - 100 nucleotit, gichc nng vn chuyn acid amin hot ho t t bo cht n cc ribosom. Mt t - ARN

ch vn chuyn c hiu mt acid amin tng ng vi n.Cu to: gm mt chui polynucleotit gp khc li ging nh hnh l c ba thy,

c nhng on xon kp theo qui tc b sung gc kim: A-U; G-X.

mt u chui c 3 gc kim t do, cc acid amin sc gn vo 3 gc kim c chvo v tr tng hp protein ribosom.

C 20 loi t - ARN tng ng vi 20 acid amin. Cc acid amin s kt hp vi t-ARN tng ng ca lum, to thnh tng lung i vo v tr tng hp protein m tht sp xp ca cc acid amin trong mch peptid th c m - ARN qui nh trc.

3.3.4.3. ARN ribosom: K hiu r .ARN

Trng lng phn t loi ny rtcao 1 - 2 triu, chim trn 80olo tng sARN. Mt ribosom l mt htnucleoproteid m phn acid nucleic lARN. ng knh ca ribosom khong200A0.

S tp hp ca chng vi chcngn i phn t s to thnh mtnh my vi m vng chc, c t chchon ho, c kh nng c bn mtm di truyn trong mch m - ARN vthc hin thng tin dng mt phnt protein chun b sn v c cu trcc hiu.

3.4. NUCLEOPROTEID

3.4.1.Nucleohiston v nucleoprotamin

ARN v ADN thng thy trong t nhin (ng vt, thc vt cng nh vus)di dng kt hp vi protein.

- Protein c bit quan trng l histon: tnh cht kim, trng lng phn t nh.Histon t do c cu trc xon a v hnh nh cu trc ny c duy tr trongnucleohiston.

Gn y mt s tc gii chng minh rng ncleohiston chit sut t mm ucha ARN gn vi protein bng lin kt ng ho tr - Phc hp ARN - histon cha


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8% ARN v 92% protein.

- Trong cc t bo sinh tinh trng thnh ca nhiu h c ADN c gnkhng phi vi hislon, m vi protamin, protamin l protein c tnh kim mnh, cngnh histon, c t l arginin cao. Tuy nhin chng c kch thc khng ng u v

nh hn, hnh nh chng c mang tnh cht c hiu chng loi.3.4.2. Nucleoprotid ca virus

Vut l mt v din hnh v cc loi nucleoproteid ng nht v t tr.

Ba c im ca vus l: trong t bo dinh dng ca vt ch chng th hin sc mt ca chng qua cc hin tng sau :

- T sinh sn

- Gy hi chng bnh

- Kh nng bin d

Nh tnh cht th 3 m virus tr thnh nguyn liu qu nghin cu v ditruyn.

Nh vy kt hp cht ch vi vt ch m vus biu hin tt c mi c tnh cas sng. Rt nhiu vus c tch ra tinh khit. Vut n gin nht v mt ho hcl gm c protein v acid nucleic. Protein c trong tt c mi vus (t 33 n 99%)

bao bc xung quanh acid nucleic, lm nhim v che chcho acid nucleic.

3.4.2.1. Virut vi khun (thc khun bo)Thng rt ln, acid nucleic ca chng thng l ADN xon i u, nm trong

mt ci "u' kt tinh nhiu mt i xng, gm nhiu n v nh protein rt gingnhau, c trng lng phn t 2.104. Thng chng c mt ci 'mui" d un ng lmcquan gn v chch. Ci ui ny c th gm nhiu thnh phn, chc phn v cutrc khc nhau nn s protein trong vus cng rt ln.

3.4.2.2. Virutng vt: C th cha ARN hoc ADN

- Vut ARN thy bo tng, vus ADN trong nhn t bo ch, cc in hnhnh: + Vut gy bi lit v vus cocksackie l nhng nucleoproteit n gin a din,ging nh vus thc vt.

+ Vut gy vim no v vus gy cm cha ARN cng mt phn t lng nh,nhng phn t ca n a din v kh ln, v ngoi nucleoprotein cn c lipid v

polysacant.

+ c bit nhm ng ch l reo virus c ARN vng xon i b sung vitrng lng phn t cao v gn ging ADN.

Vut cha ADN: virus gy bnh mn rp (herpes), bnh u g, bnh quai b,si, thuu psitlacosis, di, polima...


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Chng 4

GLUCID

4.1. I CNG V GLUCID

Glucid l hp cht ph bin trong t nhin v trong cth sinh vt. Thnh phnm bo thc vt gm trn di 80%, cht kh l glucid, m bo ng vt c t hn,khong trn di 2%. y l loi cht hu cph bin bc nht.

Glucid thc vt c di dng cht x (cellulose dng tinh bt d tr, dngng (sacarose, fructose...).

ng vt, glucid c nhiu trong gan di dng glycogen d tr, hoc c tronghuyt thanh di dng glucose.

4.1.1.nh ngha vglucid

Glucid l hp cht hu cmang nng lng, n l sn phm ca qu trnh quanghp: cy xanh nhdip lc bin CO2 v H2O thnh glucid di nh sng ca mttri:

C th ni glucid l nhng hp cht m quang nng chuyn sang dngho nng d s dng i vi a s sinh vt.

4.1.2. Vai tr ca glucid trong ssng

Cung cp nng lng cho hot ng sng, hng ngy nhu cu nng lng cang vt c bo m 60 - 80% l do glucid.

- Tham gia vo cu trc ca cc m bo (nht l m chng ). l vai tr tohnh ca glucid. V d: nhm cht quan trng ca cth l acid nucleic c thnh phn

ng ribose v desoxyribose.- Ngoi ra, trong i sng hng ngy ca ngi v gia sc, nhng glucid nh tinh

bt, ng, cellulose (rm, c, rau) chim mt t l quan trng trong thc phm.

4.1.3. Cc tnh cht ca gluci

4.1.3.1. Tnh cht l hc ca monosacand

- Tnh ho tan v quay mt phng phn cc

Cc monosacarid d tan trong nc, t tan trong ru, khng tan trong cc dung

mi hu c(nhe, benzen) v c kh nng lm quay mt phng phn cc.

- Tnh cht oxy ho kh


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Cc monosacand th hin tnh kh mnh do s c mt cc nhm chc aldchyd von t do. Trong mi trng kim v un nng, cc monosacand c th kh cc contm loi (v d Cu2+ -> cui Tnh cht ny c s dng nh lng ng kh nichung v glucose ni ring trong cc mu thc vt v ng vt. Khi kh ccmonosacand ta thu c cc ru a nguyn t tng ng. Cc ru socbit, ribit vn

c to thnh khi kh glucose (hoc fructose), ribose... thng gp trong cth sngv ng vai tr quan trng.

-Phn ng to este

Khi phn ng vi cc acid, cc monosacand to thnh cc este, trong c ngha quan trng nht l cc este phosphonc ca monosacand. Cc monosacand thamgia vo cc qu trnh trao i cht quan trng nht (nh quang hp, h hp) u dngeste phosphoric: aldehyd-3-phosphoglyceric, phosphodioxyaceton, glucose-6-

photphat, fructose-1,6-diphotphat, riboso-5-photphat...Phn ng vi hydrazin (NH2 - NH2) hoc phenylhydrazin (CH5 -NH- NH2)

Monosacand tc dng vi phenythydrazin to thnh sn phm khng tan - phenylozazon mu vng. Phenylozazon c s dng nhn bit ng khi phntch. S hnh thnh ozazon ca monosacand c th biu din nh sau:

- Tc dng vi acid phosphonc

4.1.4. Vn ng phn v mch vng ca monosacarid


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4.1.4.1. Vn ng phn

Mt trong nhng c im ca glucid (v d nh glucose v nhiu monosacandkhc) l tn ti di nhiu dng ng phn.

Mi phn t monosacand, t loi c 3 carbon trln u cha t nht mt nguyn

t carbon bt i (ngha l 4 ho tr carbon c bo ho bi 4 nhm ho hc khcnhau). V vy n c kh nng tn ti 3 dng ng phn.

- ng phn quay phi tia phn cc (+)

- ng phn quay tri tia phn cc (-)

- Cht khng c hot tnh quang hc (raxemat)

Hai ng phn u l 2 cht i khng v mt quang hc.

Da.vo cc ng phn ca triose l glycerylaldehyd ngi ta chia cc mnose

lm 2 hng tng ng: D v L.

V tr nhn xt hng D v L cho cc ng l H v OH nguyn t carbon

nm cnh nhm ru bc nht (CH2OH)- Nu OH nm bn phi l hng D

- Nu OH nm bn tri l hng L

Hng D v L ging nhau v nhiu c tnh l ha, chng ch khc nhau v khnng lm quay mt phng tia phn cc. Ngoi ra, v mt dinh dng ca ng vt gitr ca hai loi cng khc nhau. Trong cth ch yu c ng hng D.

4.1.4.2. Vn mch vng ca monosacarid

Trong cu trc ca monosacand ta thy c nhng gc hot ng cnh nhau nhaldchyd v alcol. Do chng c kh nng phn ng vi nhau to thnh dng dn xutna acetal (hemiacetal) theo s sau:


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Khi phn ng xy ra trong phn t monosacand, mt cu ni oxy sc thnhlp v monosacand s ho dng vng.

Dng vng ca monosacand c th l 6 cnh hay 5 cnh. Haworth ngh gi

monosacand c dng vng 6 cnh l panose v monosacand c dng vng 5 cnh lfuranose. V c th ci 2 dng ny nh l dn xut ca phn v furan.

Cu ni oxy c th xut hin gia nguyn t C1 - C5 (dng Piranose) hoc C1- C4long furanose)

V d:

Haworth cng ra cng thc phi cnh biu din monosacand.

dng vng glucose (hoc cc monosacand khc) c kh nng tn ti di dngng phn khng gian a v Hai loi ny khc nhau do v tr H v OH nguyn t Cl.


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i vi monosacand l p cetose nh fructose cng c th dng na acetal,nhng u ni oxy s xut hin gia C2 - C5 hoc C2 - C6

4.1.5. Cc monosacarid phbin

Trong t nhin v trong cthng vt thng gp cc monosacand sau:

4.1.5.1. D - Glucose (cn gi l ng nho)

y l loi ng ph bin nht c nhiu trong hoa qu. Trong mu ca gia sccha trung bnh 80 - 120mg%, glucose gan, bp tht c trng hp v d trdngglycogen.

Glucose c c tnh ca ng n (kh nng oxy - ho kh, dng vng, quaytia phn cc...).


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4.1.5.2. D - Galactose: cn gi l ng sa, c trong thnh phn ng 1actosesa v dng hp cht galactosid ca no (xerebrosid)

4.1.5.3. D - Fructose (fructus - qu) C nhiu trong qu chn, c v ngt mnhnht.

4.1.5.4. D - Manose: c coi l epimer ca D - glucose v ch khc glucose vtr C2 v nhm o.

Manose thng thy hoa qu (v cam) v trong phc hp vi my loi protein(nh albumin, globulin, cht nhy mucoid)

4.1.5.5. Cc pentose: l loi monosacand 5 carbon, trong t nhin c di dnga ng pentosan ( rm, c) hoc mt t t do (qu chn).

Trong cth gia sc c D - ribose v D - desoxyribose l nhm cht quan trng


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nht trong nucleoproteid.

4.1.6. Cc dn xut chnh ca monosacarid

4.1.6.1 . Cc phospho - este (hesose -phosphat)

Cc monosacand nh glucose, fructose... trong m bo sinh vt d este ho vi

H3ro4 thanh dng glucose - phosphat.

Loi cht ny rt quan trng trong qu trnh trao i vt cht v gii phng nnglng cho cthng vt.

4.1.6.2. Dn xut cha quan (hexosamin)

Mt nhm OH (thng v tr C2) c thay bng NH2

Trong cthng vt, loi ng quan ny c trong protein cht nhy cu trcmt s m.

Hai cht thng gp:

4.1.6.3. Nhm glucosid

V cu to, glucosid l nhng h p cht este gia monosacand v cht khngglucid nh ru, metyl, acid xyanhydric gi chung l gc aglucon.

Phn ln glucosid t nhin l nhng cht c, nhng vi liu lng nh va phili c dc tnh rt gi tr. V d: Saponin (ng + saponegin) l thuc long m.

4.2. PHN LOI GLUCID

Csphn loi: Ngi ta thng phn loi glucid da theo mc phc tp caphn t, ly ng n lm cs.


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Chia lm 2 loi chnh:

4.2.1. Loi ose

O se l nhng ng khng thu phn c na thng cn gi l ng nhoc monosacand. Tu theo s nguyn t carbon, loi OZA chia thnh cc nhm:

- Triose (C3H6O3)

- Tetrose (C4H8O4)

- Pentose (C5H10O5)

- Hexose (C6H12O6)

4.2.2. Loi osid

L nhng glucid phc tp do nhiu monosacand ghp li. Loi ny gm 2 nhm

ln:4.2.2.1. Holosid

Khi thu phn cho ton monosacand, nn cn gi l glucid n thun, nhm nychia ra thnh:

Oligosacand (hoc oligose): cu trc n gin gm t 2 n 3 monosacand nncn gi l disacarid v trisacand.

- Polysacand (polyose) cu trc rt phc tp gm nhiu monosacand, mt si

din nh: tinh bt, glycogen, cellulose...4.2.2.2. Heterosid

Khi thu phn, ngoi monosacand cn thy nhiu nhm khng phi glucid (nhmaglucon).

Di y ta ln lt nghin cu tng loi ni trn.

4.3. LOI OSE

Xt v cu trc, monosacarid l nhng dn xut aldehyd v ceton ca ru nhiu

nguyn t v tng t nh vy ta c alose hoc cetose.

4.3.1. Triose (C3H6O3)y l nhng monosacand c 3 nguyn t cathon. i din ca nhm ny l


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glycerylaldehyd v dioxyaceton.

4.3.2. Tetrose (C4H8O4)

Tetrose l monosacand m phn t ca n c 4 carbon. Trc kia loi ny khngc cc nh sinh vt hc ch lm, nhng sau ny ngi ta thy khi thu phnglucid, trong nhng sn phm trung gian ca qu trnh trao i cht, cng vi dng

phosphoryl ca loi hexose, pentose, cn c dng tetrose nh eritrophosphat.

4.3.3. Pentose (C5H10O5)Mt si din ca loi monosacand 5 carbon ny l:

4.3.4. Hexose (C6H12O6)


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Trong cthng vt v ngi, nhng hexose thng gp l: glucose, fructose,mannose, galactose (mt phn hexose trng thi to, mt phn dng lin kttrong thnh phn ca polysacand. Hexose t nhin: glucose, fructose, mannose,galactose thuc loi cu trc dy D - trong iu kin phng th nghim c th nhnc ng dy L.

Tt c monosacand t nhin c v ngt v d ho tan trong nc. ngt cami loi ng khng ging nhau.

Monosacand loi hexose tng i ph bin nh chng ta trnh by trn.

4.4. LOI OSID

Osid gm 2 loi chnh:

- Loi osid thun nht (hay cn gi l holosid) gm ton o se.

- Loi osid khng thun nht (heterosid) loi ny ngoi cc o se ra cn c nhmghp khng phi glucid.

Ta ln lt nghin cu my loi ph bin sau y:

4.4.1. Loi holosid

Tu s lng monosacand to thnh m nhm holosid chia ra: disacand,tnsacand, polysacand.

4.4.1.1. Disacarid. (hay cn gi l ng kp)

N c thnh lp do 2 monosacand hp li qua mch osid sau khi khi mtphn t nc .

Thnh phn nhng ng kp ch yu nh sau:

My cht ng ch l:

- Saccarose: ( glucosido - 1,2, - fructose) lin kt glucosid gia C1 ca glucosev C2 ca fructose.


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Loi ny cn c gi l ng ma hay ng c ci ng (ma c 20%, c cing c 27%).

Saccarose khng cn nhm OH glucosid t do nn khng cho nhng phn ngoxy - ho kh.

- Lactose ( - galactosido - 1,4, - glucose) ng ca sa hm lng lactosethay i tu loi sa. y l loi ng kp c nht c tng hp cth gia sc -

Lactose c tnh oxy ho khin hnh ca ng.

Maltose ( - glucosido 1 ,4 - - glucose)Cn gi l ng mch nha. ng ny sinh ra trong ng tiu ho do s thu

phn tinh bt hoc glycogen bi men amylase.

- Cellohiose: ( - glucosido - 1,4, - glucose) l ng kp thu c khi thuphn cellulose cha trit .


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4.4.1.2. Polysacarid

Polysacand l loi a ng c trng lng phn t rt cao, do nhiu gcmonosacarid hp li m thnh. Cng thc chung ca polysacand l (C6H10O5)n.

cc loi polysacari ng k nht l:

- Tinh bt

- Glycogen

- Cellulose

- Chitin

Tinh bt

Tinh bt l loi glucid d tr ca thc vt c lluul thnh trong qu trnh quang

h p. N l ngun thc n rt quan trng i vi ng vt, nht l ng vt nngnghi p. Phn ng c trng nht ca tinh bt l tc dng vi iod (hoc dung dchlum) cho mu xanh chm.

Hm lng ca tinh bt khc nhau cc loi thc vt:

V d: go t cha khong: 75,81%

ng cha khong: 70,08%

Cu to ho hc ca tinh bt c to thnh t cc gc a glucose gm 2 thnh

phn: + Amylose (chim 10 - 20%) - cht ny tan trong nc, khng to h, vi iodcho mu xanh, cc gc a - glucose c lin kt vi nhau qua mch glucosid 1 - 4 tothnh mch thng.

+ Amilopectin (chim 80 - 90%) khng tan trong nc vi iod cho mu tn gm cc gc a - glucose lin kt vi nhau qua mch glucosid 1- 4 v 1-6 to cho phnt tinh bt c cu to phn nhnh.


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Glycogen (hay cn gi l tinh bt ng vt)

l loi glucid d tr trong gan v m bo ng vt. Cu to ho hc caglycogen ging tinh bt, tc l cu to t cc - glucose, nhng mc phn nhnhca glycogen mnh hn .

Ceuulose (hay cn gi l cht x)

l loi polysacarid ph bin nht ca thc vt. N c cu to t nhiu gc - glucose qua mch - glucosid 1- 4 to thnh chui thng khng phn nhnh, s lng - glucose khong vi chc vn. Trong thc vt, cellulose lin kt thnh cc b si lcc mi xen qua cc lin kt hyrogen.

Ceuulose ch b phn ho bi enzym ceuulase vi sinh vt cho nn c th gia scmun s dng cellulose phi nhs hot ng ca vi sinh vt c trong d c ca loinhai li bi v trong cth gia sc khng c enzym cellulase.

Ngoi cc loi ng thng g p ni trn chng ta cn gp mt sa ng

nh: chinh, mun, hemicellulose, dextran...Chitin

Chitin l mt polysacand thun c cu to t cc n v N-acetylglucosanlinni vi nhau bng lin kt - glucosid 1- 4. S khc nhau duy nht v mt ha hcgia chnh v cellulose l s thay th nhm hydroxyl v tr C2 bng mt nhm cacetyl ha (CO3-CO-NH-):


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Chitin c dng si ging nh cellulose v ng vt cng khng tiu ha c

chnh. Chitin l thnh phn c bn ca lp v cng ca nhiu loi sinh vt, lpolysacand ph bin trong t nhin ch sau cellulose.

Inulin:l mt polysacand d tr ca thc vt. n v cu to l fructose. Trnglng phn t ca insulin thp v n ch c khong 30 gc fructose, do polysacandny d dng ho tan trong nc.

loi ng cc thi k pht trin u thng c a ng cu to do fructose. Khi

chn mui a ng ny s pht trin thnh tinh bt.

Hemiceuulose:y l tn chung ca nhiu loi a ng thng gp trong rm,g, li ng...

a ng loi ny nu c n v cu to t:

+ Mannose th gi l mannan

+ Arabinose th gi l araban

+ Galactose th gi l galactan+ Cylose th gi l cylan

Dextran: l sn phm ca vi khun

Dextran cu to t -glucose ni mch glucosid 1 - 4 v 1 - 6, nhng khcglycogen, mch glucosid 1 - 4 y l mch r.

4.4.2. Loi heterosid

Heterosid l loi a ng khng thun nht, c cu to cao phn t v cu trc

phc tp. Trong thnh phn ca n ngoi cc monosacand ra cn c cc dn xut camonosacand nh hexosamin, hexosulfat...

Heterosid chia lm nhiu lp khc nhau tu tnh cht v cu trc. ng k nht l2 lp:

- Glucopolysacand

- Mucopolysacarid

4.4.2.1. Mucopolysacarid: (mucor - cht nhy)

y l loi a ng thng gp trong m lin kt, cht trung gian gia cc tbo v cc dch nhy. Ba loi mucopolysacand ng ch l:


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-Acid hyaluronic

Loi a ng nhy ny c trong dch bao khp, trong thu tinh th mt, trongnhiu m bo ca ng vt khc.

Trng lng phn t khong 200 - 500 nghn, ho tan trong dung dch rt nht.

Nhc tnh ny nn acid hyaluronic c v nh cht xi mng gn vi cc t bo cam trong cth.

Khi thu phn acid hyaluronic ta thu c N- acetylglucosamin v acid D-glucoronic.

Hai thnh phn ny ni vi nhau theo s don sau:

Nhiu vi khun c kh nng ph hoi mch m bo, nc ong, nc rn... c loienzym hyaluronidase phn gii acid hyaluronic. Enzym ny lm hng cht nhy gn t

bo nn vi khun d hot ng.

u mi nhn ca tinh trng cng c acid hyaluronic nn tinh trng c kh nng

xm nhp vo t bo trng thc hin qu trnh th tinh.- Chondroitin sulfat

Cht ny cha nhiu trong m lin kt, cht tnh kim ca sn di dng phccht nhy chondromucoid.

Trng lng phn t rt cao gm acetyl-galactosamin, acid glucoronic - cu trcdon nh sau:

Heparin (Hepar - gan)

y l loi a ng tm thy u tin gan, sau c, tim, phi...

Trng lng phn t khong 17.000 thnh phn gm galactosamin, acidglucoronic v gc sulfat.


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Hepann c kh nng lin kt vi trombokinase, lm cho cht ny khng tham giavo qu trnh ng mu c. Chnh ming con a cng c cht hepann ny, chonn khi a cn mu thng chy ra nhiu, kh ng.

Trong y hc v th y hepann c dng lm cht n nh mu v chng ngmu (khi truyn mu).

4.4.2.2. GlucopolysacandL loi a ng phc tp c tnh keo nh mucopolysacand nhng khng cha

dn xut an lin nh hexosann. i din ca nhm ny thng l:

- Pectin thc vt: l nhng cht gi vai tr nha gn t bo m thc vt.

- Glucopolysacand ca vi khun: thng c trong cu to gip m, c c tnhbn i vi men tiu ho. 'Nhvy vi khun sng c trong nhng mi trng nhnc bt, dch rut...


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Chng 5

LIPID

5.1. I CNG V LIPID

5.1.1. Khi nim chungLipid l lp hp cht hu cph bin trong t nhin v trong c thng vt,

thc vt v vi sinh vt. Lipid c c tnh khng ho tan trong nc, ch ho tan trongcc dung mi hu cnhe, cloroform, benzen, cn, aceton... (nhng khng phi milipid u ho tan nh nhau trong tt c cc dung mi ni trn, m mi lipid ho tantrong dung mi tng ng ca mnh, nhc tnh ny ngi ta c th phn tch ringtng loi).

Tn gi lipid (bt ngun t ch Hy-lp lipos: m) dng ch chung cc loi m,

du v cc cht bo ging mng vt v thc vt.V mt ho hc lipid l nhng este gia alcol v acid bo in hnh l cht

triglycerid.

5.1.2. Vai tr ca lipid

Lipid i vi cth sinh vt c nhiu ngha quan trng:

Chc nng dtrnng lng

Lipid l cht d tr nng lng, tit kim th tch nht, khi oxy ho 1 gam mcth thu c 9,3 Kem. em so vi lng cm ca mt gam ng hoc protein (4,lKcalll gam) th lng cam sn ra ca lipid nhiu gp i. Nhu cu nng lng hng

ngy ca ng vt do mcung cp khong 30% hoc hn na.Chc nng cu to mng tbo

Trong mng sinh hc lipid trng thi lin kt vi protein to thnh h p chtlipoproteid chnh nhtnh cht ca hp cht ny to cho mng sinh vt c c tnhthm thu chn lc, tnh cch in. l nhng thuc tnh ht sc quan trng ca t

bo sinh vt.

Chc nng dung mi ho tan vitamin

Lipid l dung mi ho tan nhiu loi vitamin quan trng nh vitamin A, D, K, E.V th nu khu phn thiu lipid lu ngy th ng vt d mc bnh thiu vitamin ktrn.


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Chc nng bo v chc

Lipid di da ca ng vt c tc dng gi m v gim cho c th nh tnhm, dn nhit km.

Chc nng cung cp nc ni sinh

i vi loi ng vt ngng, ng vt di c, cc loi su kn lipid cn lngun cung cp nc, v khi oxy ho long mth c l07g nc c sinh ra.

Ngoi ra, lipid cn c th lin kt vi nhiu cht n gin khc thnh nhng phchp c tnh cht sinh hc khc nhau. Nhng phc hp y gi vai tr quan trng trongcc hot ng v thn kinh v bp tht.

5.1.3. Thnh phn cbn ca lipid

Trong phn ln cc cht lipid c cha hai thnh phn chnh l alcol v acid bo.

Alcol v acid bo c ni vi nhau bng lin kt este hoc lin kt amid. Ngoira, lipid cn c th kt hp vi glucid to thnh glucolipid c vai tr cu trc mnghoc kt hp vi protein to thnh lipoprotein gi vai tr quan trng trong vic ho tanv vn chuyn lipid trong mu, gip hp thu vitamin tan trong lipid.

5.1.3.1. Alcol ca lipid

Alcol ca lipid c chia thnh nhiu nhm khc nhau: glycerol, cc alcol bccao, aminoalcol v sterol. Ngoi ra, trong t nhin cn c alcol khng no, v d phytol

(l mt thnh phn ca chlorophyl v lycophyl) l mt dthydroxylalcol khng no cnhiu lin kt i l cht mu ta trong c chua.

Glycerol l mt alcol a chc c trong thnh phn cu to glycerid vphosphatid.

Cu trc ca glycerol nh sau:

cc alcol cao phn t thng tham gia vo thnh phn ca cc cht sp.

Aminoalcol tham gia vo thnh phn cu to ca cerebrosid v mt sphosphatid, Aminoalcol thng gp l:

- Sphingozin (thnh phn cu to ca sphingolipid):

- Cerebrin c nhiu trong nm men, ht ng):


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- Sterol: tiu biu cho sterol l cholesterol trong m bo ng vt. Sterol khi esteha vi acid bo to thnh sterid.

5.1.3.2. Acid bo

Tnh cht ca lipid ph thuc rt nhiu vo thnh phn acid bo. Acid bo c

nhiu oi: mch thng, mch nhnh, mch vng. bo ho (no) ca acid bo khcnhau gy ho mc tnh tan chy cc nhit ring bit. Tr mt vi trng hp c

bit, cn hn ln cc acid bo u cha chui cc bon chn.

Cc acid bo thng gp:

Tn gi cng thc Ni c nhiu

- Acid butylic

- Acid caproic

- Acid caprylic

- Acid palmitic

- Acid steanc

- Acid arachidic

CH3(CH2)2 COOH

CH3(CH2)4 COOHCH3(CH2)6 COOH

CH3(CH2)14 COOH

CH3(CH2)l6 COOH

CH3(CH2)18 COOH

Msa (b)

B, da

B, da, no c

Du mng, thc vt

Du mng, thc vt

Du lc

5.2. PHN LOI LIPID

Cs phn loi lipid: Da vo thnh phn ho hc ngi ta chia lipid ra lm 2lp: Lp lipid n gin: l nhng este ca alcol v acid bo.

- Lp lipid phc tp: ngoi alcol v acid bo cn c cha cc dn xut phospho,azot, sulfua...

5.2.1. Lp lipidn gin

Bao gm: - Cc glycerid trung tnh

- Cc sp tc cerid

- Cc sterid

5.2.1.1. Mtrung tnh (triglycerid)

*i cng

Cht bo l este ca glycerin v acid bo, do ngi ta cn gi l glycerid.

Md tr trong cthcc m m. S lng ca n thay i tu trng thi h

thn kinh, tu khu phn, tu ging c ci, tu tui v cc yu t khc na. S lng c th x dch trong khong 10 - 30% so vi th trng (ln v bo c th ln ti


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50%).

* Cng thc cu to ho hc ca m(triglycerid)

Nu R1, R2, R3 ging nhau gi l mng nht, cn Rl, R2, R3 khc nhau gi lmhn hp. Loi sau thng ph bin hn.

V d:

*L ha tnh ca lipid

Nhit tan chy ca mthp

Mi loi mc tan chy khc nhau ph thuc vo bo ho ca acid bo mn cha. bo ho thp th nh

Hoa Sinh Dong Vat

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