Essential and trace ionsEssential and trace ions

Ions with biochemical functions and have deficiency syndrume are :

Iron and Iodide

Ions studied are :

iodide, copper,zinc,sulfur,chromium ,ma

nganese,selenium, etc. ,iron1

Iron functions in respiratory chain are:

i – an electron carrier ii- transport of molecular

oxygen

Iron

Most iron is associated with protiens

-: First : Hemoproteins

responsible for respiration Two group proteinsand for transport oxygen .

2

((aa ) )Cytochrome – cCytochrome – c: :

An respiratory Enzyme, where iron is complexedcovalently with the protein portion in a porphyrin

ring ) heme ring ( .

Iron act as electron carrier by changing from

ferrousto the ferric form and reversibly .

Cytochrome –c role is in oxidation – reduction

process of iron .

3

( (bb ) ) Hemoglobin and Hemoglobin and myoglobinmyoglobin

Hemoproteins which store and/or transport Oxygen

-Myoglobin:

. A single polypeptide with one oxygen binding site

An oxygen carrying protein.

Binds and releases oxygen through changes in

oxygen conc. in sarcoplasma of skeletal muscle cells. 4

HemoglobinHemoglobinFound in high conc. in red blood

cells.It binds to oxygen in lungs and transports

it to body cells, also transports CO2 from tissues to lungs .

Hemoglobin has 4 protein chains ,each one has a heme ) porphyrin ring ( and ferrous

iron .

Iron complexes O2 by using its vacant pair of non bonding electrons .

5

Uptake and release of O2 is influensed by -:

1 -The oxygen tension. 2 -PH

3 -Presence of 2,3 diphosphoglycerate . 4 -CO2 concenteration.

Patients with iron-deficiency animia have- :

a- Decreased capability for oxygen transport.

b- Decreased in hemoglobin synthesis.

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Iron storage and transport Iron storage and transport proteinsproteinsBody handeling of iron requirments is by

storage and transport proteins

a – The iron storage proteins Found in liver, bone marrow and

spleen.Ferritin :

- A water soluble iron protein built up from apoferrtin and micelles of ferric

hydroxide-phosphate complex . Iron is stored in ferritin as Fe3+ form and

released as Fe2 +

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HemosiderinHemosiderin

A water insoluble protein considered as

a dehydrated form of ferritin .

b – Iron transport proteins

Transferrin

Major protein in blood plasm synthesised by the liver, and it binds

two ferric iron per molecule . Transferrin releases iron to blood red

cells through receptor on red cell surface . 8

2- CO32- + transferrin+Fe3+ transferrin.Fe

3+.CO3

(-2ransferrin.Fe3+ .co32- + co2

2- + Fe3+

transferrin.2)Fe3+.co3

Iron lost in human body through bile secretions, menstrual flow & other

secretions. hemorrhage,

Daily iron requirements : - 10-12 mg for males 12-18mg for females

Males lose o.6 mg iron dailyNon pregnent females lose 1.2 mg-1.8 mg

iron daily Pregnent females lose 3-4 mg

daily9

Iron disteribution in normal Iron disteribution in normal adultsadults

Men Women

Hemoglobin 3050 mg 1700 mg

Myoglobin 430 mg 300 mg Enzymes )transport( 10 mg

6 mg Ferritin) storage( 750 mg 300 mg

Total 4248 mg 2314 mg

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Iron AbsorptionIron AbsorptionIn food diet :

- 1 -Iron in liver and muscle is better absorbed than iron in eggs and

vegetables , because iron is bond to phytate )inositol hexaphosphate (.

3 - Iron in wheat , corn & black beans is relatively unavailable for body use .

2 - Iron in hemoglobin is well absorbed , because it is still bond to porphyrin ring .

4 - Iron in ferritin is poorly absorbed , because the protein must firstly digested

by G.I. proteases before absorption . 5 - Released iron complexed with

sugars ,ascorbic acid,citric acid and amino acids .

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Absorption mechanismAbsorption mechanism

Cooking food facilitate iron ligand breakdown increasing iron availability

in gut .Low stomach PH allows reduction of ferric

Fe3+ to ferrous Fe2+ with presence of reductant) ? (

Major iron absorption is in small intestine mostly in the duodenum .

Exess bicarbonate secreated by pencreas oxidises ferrous Fe2+ to

ferric Fe3 +

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Three hypothesis for Three hypothesis for absorptionabsorption

1 – The mucosal blook hypothesis- :

Fe3+

Fe2+

(H)

Fe2+

Fe3+

Apoferritin

Apoferritin

(O)

Ferritin

Fe2+ Fe2+

Fe3+

Transferrin

To liver for

storage

To bone marrow for use

Small intestine

Mucosal cell Blood

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22 – – Active transport hypothesisActive transport hypothesis

Fe 3+

Fe 3+

Fe 2+

Fe 2+Fe 2+

Endogenous ligands

macromolecules

(H)

(O)Biological energy

compounds ATP

Transferrin

Lumen of

intestine

Mucosal cell

Blood

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33 – – The ion-chelate hypothesisThe ion-chelate hypothesis

Fe3+

Fe2+

Endogenous ligands

Fe-chelate

Ferritin )storag (

Fe-chelate

Storage

Transferrin

R.B.CExcreation

Fe3+

Lumen of

intestine

Mucosal cell

Blood

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