Dr. Siham Gritly 1

Principle of Biochemistry 3-Simple and Complex Carbohydrates

Course code: HFB324

Credit hours: 3 hours

Dr. Siham Gritly

Dr. Siham Gritly 2

Terms should be learned vocabulary

• Carbohydrate; generic name for simple and complex sugars; chemically carbohydrates are polyhydroxyl aldehydes or polyhydroxyl ketones

• Aldose; sugar containing an aldehyde functional group

• Ketose; sugar containing a ketone functional group• anomeric carbon; the carbon atom in a cyclic

monosaccharide which, in the linear monosaccharide, holds the aldehyde or ketone functional group

Dr. Siham Gritly 3

vocabulary • Asymmetric carbon; carbon atoms attached to four different atoms or groups or

chiral carbon

• Chiral carbon; atoms have four different atoms or groups covalently attached to them

-linked sugars; refers to;

(a) the geometry of the glycosidic bond (α = opposite side of the sugar ring from the free CH2OH; β = same side),

(b) which carbon on ring A is linked to which carbon on ring B.

• Stereoismers; are compounds having two or more chiral carbons that have the same four groups attached to carbon atoms but are not mirror images to each other

• D-sugar; the stereoisomeric form of monosaccharide. One of a set of isomers whose molecules have the same atoms bonded to each other but differ in the way these atoms are arranged in space.

Dr. Siham Gritly 4

vocabulary

• Furanose; cyclic form of glucose monosaccharide whose structure is a five-membered ring

• Pyranose; cyclic form of glucose; monosaccharide in a six-membered ring form

• glycosidic bond; ether bond joining two monosaccharides

• hemiacetal or hemiketal; cyclic conformation of simple carbohydrates; formed by reaction of the aldehyde (or ketone) and one of the hydroxyls on the carbohydrate

Dr. Siham Gritly 5

vocabulary

• Monosaccharides. "Simple sugars" with the formula (C H2O)n. The word carbohydrate refers to the fact that this class of molecules consists of hydrates of carbon.

• Disaccharides; "Simple sugars" contain two monosaccharides units attached to one another through acetal bonds or as known glycosidic bonds

• Oligosaccharides. complex sugar Polymeric molecule of sugar comprising 2-10 covalently linked monosaccharide units. Often found conjugated to other classes of biomolecules including lipids and proteins.

• Polysaccharides. complex sugar Larger polymers of simple sugars. On the order of hundreds to thousands of monosaccharide units as linear or branched polymers

Dr. Siham Gritly 6

vocabulary• Aldehyde ; Any of a class of highly reactive organic chemical

compounds obtained by oxidation of primary alcohols, characterized by the common group CHO, and used in the manufacture of dyes, and organic acids.

• Aldehydes are oxidized to carboxylic acids and take part in many addition reactions

• ketone Any of a class of organic compounds, such as acetone, having a carbonyl group linked to a carbon atom in each of two hydrocarbon radicals and having the general formula R(CO)R ,

• Ketones don't have that hydrogen atom and are resistant to oxidation. They are only oxidised by powerful oxidising agents which have the ability to break carbon-carbon bonds.

Dr. Siham Gritly 7

Dr. Siham Gritly 8

Carbohydrates are polyhydroxy aldehydes or ketones (Constructed from the atoms of

carbon, oxygen and hydrogen)

• In aldehydes (aldose) the carbonyl is bonded to one carbon and one hydrogen and are located at the ends of carbon chains. Formula H-(CHOH)x(C=O)-

• In ketones (Ketoses) carbonyl group (C= O) is bonded to two carbons within a carbon skeleton

Dr. Siham Gritly 9

In aldehydes (aldose) the carbonyl is bonded to one carbon and one hydrogen and are located at the ends of carbon chains. H-(CHOH)x(C=O)- easily oxidized In ketones (ketose) carbonyl group (C= O) is bonded to two carbons within a carbon skeleton no hydrogen atom

Glycerildyhide

H H | |H—C—C—C—H | " | H O H

H H H | | |H—C—C—C=O | | H H

Dr. Siham Gritly 10

• The major carbohydrates found in the body are structurally related to the;-

• 1-aldotriose glyceraldehyde • 2-ketotriose dihydroxyacetone. • All carbohydrates contain at least one

asymmetrical (chiral) carbon and are, therefore, optically active.

Dr. Siham Gritly 11

Aldotriose and ketotriose glyceraldehyde is especially

important because the more complex monosaccharides may be considered to be derived from them

Dr. Siham Gritly 12

Carbohydrate Nomenclature

• Monosaccharide• Disaccharides, • Oligosaccharides• Polysaccharides

Dr. Siham Gritly 13

Monosaccharides

• The common monosaccharides (hexoses) of living organisms are:

• (glucose, galactose, fructose) C₆H₁₂O₆• (ribose, deoxyribose, ribulose, xylose) 5-

carbon pentoses (C5H10O4).

• Contain 3-7 carbon atoms.(trioses, tetroses, pentoses, hexoses and heptoses)

• Contain hydroxyl groups -OH• Carbonyl group C=O

Dr. Siham Gritly 14

• The 5-carbon monosaccharide ribose is an important component of;-

• - coenzymes (e.g., ATP, FAD, NAD)• - the backbone of the genetic molecule RNA• Deoxyribose which is a component of DNA •

Dr. Siham Gritly 15

Aldoses contain an aldehyde (-CHO ) functional groupat one end e.g. glucose

Ketoses contain a ketone (C=O) functional group usually at C #2. e.g. fructose

glucose is the most important monosaccharide

Dr. Siham Gritly 16

the nomenclature and functional group for monosaccharides

Number of Carbons

(Generic monosaccharide

name)

Aldose Functional

Group

Ketone Functional Group Relevant examples

3

(Triose)Aldotriose

Ketotriose

TriuloseGlyceraldehyde, Dihydroxyacetone

4

(Tetrose)Aldotetrose

Ketotetrose

TetruloseErythrose

5

(Pentose)Aldopentose

Ketopentose

PentuloseRibose, Ribulose, Xylulose

6

(Hexose)Aldohexose

Ketohexose

HexuloseGlucose, Galactose, Mannose, Fructose

Dr. Siham Gritly 17

Conformation of monosaccharides trioses, tetroses, pentoses, hexoses

Dr. Siham Gritly 18

StereochemistryIsomerism

• Stereochemistry deals with arrangements of atoms in molecules and the effects of these arrangements on the chemical and physical properties of substances

• Isomerism are compound have the same structural formula but differ in configuration

• The presence of asymmetric carbon or chiral (carbon atoms attached to four different atoms or group) allows the formation of isomer

• Different groups are attached it is easy to move any two or groups of atoms to other position and rotate the new structure

Dr. Siham Gritly 19

D and L isomerism

• Organic substances usually are optically active• The presence of asymmetric carbon atoms give optical

activity on the compound • If Plane-polarized light is passed through a solution of

the substances, ;-the plane of light is rotated to• - the right (dextrorotary substances) • -or to the left (for levorotatory )• expressed as• *dextrorotary (D)• *levorotary (L)

Dr. Siham Gritly 20

• The direction and extend of the rotation of a particular compound depend on;

• -concentration of the substances• -temperature • -wave of the light• Enzyme function specify the particular

configuration such as L-glutamate dehydrogenase

Dr. Siham Gritly 21

The majority of saccharides in nature have the "D" isomer

The orientation of the –H and –OH groups around the carbon atom adjacent to terminal alcohol carbon (CH2OH) carbon 5 determine whether the sugar is D or L isomer

Fischer projection Haworth Projection of β-D-Glucose

Dr. Siham Gritly 22

Haworth Projection of α- and β D-GlucoseIn α-D-glucose the anomeric carbon’s –OH group is on the right. In the Haworth projection of α-D-glucose illustrated below the –OH group points down and β D glucose OH pointed up.

Dr. Siham Gritly 23

Cyclic Fischer Projection of α-D-GlucoseIn cyclic structure or Fisher projection the anomeric hydroxyl are positioned to right resulting in alpha

configuration

Cyclic Fischer Projection of α-D-Glucose

Dr. Siham Gritly 24

Ring and chair configuration of glucose

Dr. Siham Gritly 25

aldose-ketose isomerism

• The carbonyl group of the keto or aldose functional group is considered to be closest to the "start" of the carbon chain.

• The carbon thus identified as the "first" carbon in the chain is carbon #1. The remaining carbons are numbered sequentially.

• In Fischer Projections, the "D" isomer will have the hydroxyl (-OH) functional group located on the right-hand side of the chiral C.

Dr. Siham Gritly 26

Fischer projection of glyceraldehyde Aldotriose D,L designation refers to the configuration the

highest-numbered asymmetric center

Dr. Siham Gritly 27

Fischer projections for some aldotetroses

Dr. Siham Gritly 28

• aldotetroses: – Carbon 1 is at the end closest to the aldehyde carbonyl – Carbon 3 is the highest numbered carbon that is chiral

(carbon 4 is not chiral because it contains two hydrogens)

– The "D" or "L" nomenclature therefore refers to the chirality of carabon 3. The "D" form has the OH group on the right-hand side of carbon 3; the "L" form has the OH group on the left-hand side.

– Carbon 2 is chiral, and the different isomers of this aldotetrose are indicated by different common names

Dr. Siham Gritly 29

Fischer projections for some ketopentoses

Dr. Siham Gritly 30

ketopentoses

• Carbon 1 is the end closest to the keto group • Carbon 4 is the highest chiral carbon and

determines the "L" or "D" isomer nomenclature for the saccharide

• Carbon 3 is also chiral, and its chirality determines the common name

• Carbon 2 is not chiral, neither is carbon 1, or carbon 5.

Dr. Siham Gritly 31

Cyclic monsaccharide structures and anomeric formsα and β anomers

• Ring structure of CHO• In solution the molecules cyclize by a reaction between

carbonyl group and hydroxyl group • If the sugar contain an aldehyde it is called hemiacetal• If the sugar contain a keto group it is called hemiketal• In cyclic structure or Fisher projection the anomeric

hydroxyl are positioned to right resulting in alpha configuration

• If the anomeric hydroxyl are positioned to left the structure would be in beta configuration

Dr. Siham Gritly 32

• The resulting chirality of the aldehyde carbon (or keto carbon in ketoses) in the cyclic structure can be either the α- or β- form. This carbon is termed the anomeric carbon, and the α - and β - forms are anomers.

Dr. Siham Gritly 33

pyranose and furanose ring structures

• "Pyranose" is used to refer to the pyran ring structure (6-membered ring with 5 carbons and 1 oxygen) Cyclic sugars that contain a six membered ring are called "pyranoses

• For five membered rings (four carbons and 1 oxygen) the structure is a furanose ring. Cyclization is reversible

Dr. Siham Gritly 34

Cyclic form of glucose is a pyranose Cyclic form of fructose is a furanose

• The pyranose ring is formed by the reaction of the hydroxyl group on carbon 5 (C-5) of a sugar with the aldehyde at carbon 1.

• This forms an intramolecular hemiacetal.

• If reaction is between the C-4 hydroxyl and the aldehyde, a furanose is formed hemiketal.

• The pyranose form is more stable than the furanose form,

Dr. Siham Gritly 35

• glucose forms an intra-molecular hemiacetal by reaction of the aldehyde on C1 with the hydroxyl on C5, forming a six-member pyranose ring, named after the compound pyran

Dr. Siham Gritly 36

The furanose and pyranose forms of D-glucose

The furanose forms of D-glucose four carbons and 1 oxygen

The pyranose forms of D-glucose 6-membered ring with 5 carbons and 1 oxygen

Dr. Siham Gritly 37

glucopyranose The ring structure representations of "Haworth

Projections“

The pyranose ring is formed by the reaction of the hydroxyl group on carbon 5 (C-5) of a sugar with the aldehyde at carbon 1. This forms an intramolecular hemiacetal

Dr. Siham Gritly 38

chair configuration of the glucopyranose ring

chair configurationThe α and β anomers of glucose chair form. the position of the hydroxyl group (red or green) on the anomeric carbon relative to the CH2OH group bound to carbon 5: they are either on the opposite sides (α), or the same side (β).

Dr. Siham Gritly 39

mutarotation of glucose rings Two ring forms of glucose differ in whether the hydroxyl group attached to carbon number 1 is fixed below (alpha glucose ) or above (beta glucose )

A change in the specific optical rotation of light that takes place in the solutions of freshly prepared sugars; Carbohydrates can change

spontaneously between the α and β configurations: a process known as

mutarotation.

α and β configurations Found in equilibrium and spontaneously are

interconverted (mutarotation

Dr. Siham Gritly 40

Pentose sugar ribose

• Ribose is an organic compound with the formula C5H10O5

• Ribose constitutes the backbone of RNA, a biopolymer that is the basis of genetic transcription

• Once phosphorylated, ribose can become a subunit of ATP, NADH, important in metabolism

Dr. Siham Gritly 41

Ribose is an aldopentose (a five-carbon aldehyde)

Dr. Siham Gritly 42

Deoxyribose

• deoxyribose, also called d-2-deoxyribose, five-carbon sugar component of DNA (deoxyribonucleic acid), where it alternates with phosphate groups to form the “backbone” of the DNA polymer and binds to nitrogenous bases.

• The presence of deoxyribose instead of ribose is one difference between DNA and RNA (ribonucleic acid).

Dr. Siham Gritly 43

Deoxyribosereplacement of the hydroyl group at the C2

position with hydrogen, leading to the net loss of an oxygen deoxy.

Dr. Siham Gritly 44

Disaccharides • Disaccharides; contain two monosaccharides units

attached to one another through acetal bonds or as known glycosidic bonds

• Covalent bonds between the anomeric hydroxyl of a cyclic sugar and the hydroxyl of a second sugar (or another alcohol containing compound) are termed glycosidic bonds, and the resultant molecules are glycosides.

• The linkage of two monosaccharides to form disaccharides involves a glycosidic bond. Several physiogically important disaccharides are sucrose, lactose and maltose

Dr. Siham Gritly 45

Glycosidic bond

• Glycosidic bond are formed between hydroxyl group of one monosaccharide and hydroxyl group of the next with the removal of water

• Glycosidic bonds involve the hydroxyl group of the anomeric carbon (keto or aldehyde) of one member of the pair of monosaccharide and hydroxyl group on carbon 4 or 6 of the second member

Dr. Siham Gritly 46

• Glycosidic bond can be α or β• Glycosidic bonds may be designated • - α 1-4, β 1-4, α 1-6 and so on• Important disaccharides are• 1-maltose• 2-lactose• 3-sucrose

Dr. Siham Gritly 47

Lactose. This disaccharide is comprise of a galactose linked to glucose via a β-1-4 glycosidic bond. "Milk sugar" - it is the principle carbohydrate of milk. Must be broken down into galactose and glucose by the enzyme lactase.

Dr. Siham Gritly 48

Sucrose. This disaccharide is glucose-α-1,2-fructose. "Table sugar". No free anomeric carbon, therefore, not a reducing sugar.

Dr. Siham Gritly 49

Maltose. This disaccharide is glucose-α-1,4 glucose. "Grain sugar". Formed from the partial hydrolysis of starch. Has a free anomeric carbon and is therefore a reducing sugar.

Dr. Siham Gritly 50

Complex carbohydrates • When polysaccharides are composed of a single

monosaccharide building block, they are termed homopolysaccharides example starch and glycogen.

• Polysaccharides composed of more than one type of monosaccharide are termed heteropolysaccharides, give sugar and

non-sugar like SO4 or NH4 gp e.g.

glycosaminoglycans ( found in connective tissue)

heparin present in mast cells as anticoagulant

Dr. Siham Gritly 51

polysaccharides; consist of many mono-saccharides. the main

monosaccharide found in polysaccharides is D-glucose. Polysaccharides of nutritional important are

Dr. Siham Gritly 52

Polysaccharides

Glycogen 1- Glycogen

• Made and found in human bodies• Glycogen is the major form of stored carbohydrate in

animals. Stored in liver and muscle• This vital molecule is a homopolymer of glucose in α–(1,4)

linkage• Glycogen is a very compact structure that results from the

coiling of the polymer chains• Not found in plants• Saved for later use; the liver contain enzyme which

convert glycogen to glucose through the process known as glycogenlysis.

Dr. Siham Gritly 53

Glycogen

Dr. Siham Gritly 54

2-Starch

is a storage polysaccharide composed of glucose monomers

• Its structure is identical to glycogen,

Starch -- 2 forms: • amylose: linear polymer of α(1-> 4) linked glucose

residues

• amylopectin: branched polymer of α(1-> 4) linked glucose residues with α(1-> 6) linked branches

Dr. Siham Gritly 55

• starch; occur mainly in plant kingdom. Important sources are cereals, millets, roots, tubers formed in nature in large amounts.

• Starch hydrolyzed by amylase enzyme present in saliva and in pancreatic juice to form maltose (disaccharide).

• during hydrolysis starch formed intermediate product called dextrin. complete digestion of starch formed glucose;

• starch--------dextrin----------maltose------------glucose

Dr. Siham Gritly 56

Starch formsamylose

Dr. Siham Gritly 57

amylopectin

Dr. Siham Gritly 58

• 3-Dietary fiber is a carbohydrates (or a polysaccharide) that is incompletely absorbed in humans and in some animals.

• *Dietary fiber consists mainly of cellulose, a large carbohydrate polymer that is indigestible because humans do not have the required enzymes to digest it. There are two subcategories: soluble and insoluble fiber. Whole grains, fruits (especially plums, and figs) and vegetables are good sources of dietary fiber.

Dr. Siham Gritly 59

CelluloseCellulose in fibers is also a polymer of glucose

monomers ,but using beta rings (1-4 bond)

Dr. Siham Gritly 60

Dr. Siham Gritly 61

Polysaccharide Functions

• Polysaccharides functions related to• storage, • structure • protection.• Energy

Dr. Siham Gritly 62

Carbohydrates metabolism

Dr. Siham Gritly 63

Diseases associated with Carbohydrates

• Diabetes mellitus• Galactosemia• Glycogen storage diseases • Lactose intolerance

Dr. Siham Gritly 64

References

• Murry K. Robert, Granner K. daryl, Mayes A. peter, Rodwell W. Victor (1999). Harpers Biochemistry. Appleton and Lange , twent fifth edition

• Campbell, Neil A.; Brad Williamson; Robin J. Heyden (2006). Biology: Exploring Life. Boston, Massachusetts: Pearson Prentice Hall

• A. Burtis, Edward R. Ashwood, Norbert W. Tietz (2000), Tietz fundamentals of clinical chemistry

• Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. pp. 52–59

• Maitland, Jr Jones (1998). Organic Chemistry. W W Norton & Co Inc (Np). p. 139. ISBN 0-393-97378-6.

• Nelson DL, Cox MM (2005). Lehninger's Principles of Biochemistry (4th ed.). New York, New York: W. H. Freeman and Company.

• Matthews, C. E.; K. E. Van Holde; K. G. Ahern (1999) Biochemistry. 3rd edition. Benjamin Cummings.• http://wiki.answers.com/Q/What_is_dehydration_synthesis#ixzz2BuiK645

Dr. Siham Gritly 65

• Sareen Gropper, Jack Smith and James Groff, Advanced Nutrition and Human Metabolism, fifth ed. WADSWORTH

• Melvin H Williams 2010; Nutrition for Health, Fitness and Sport. 9th

ed, McGraw Hill• • Heymsfield, SB.; Baumgartner N.; Richard and Sheau-Fang P. 1999.

Modern Nutrition in Health and Disease; Shils E Maurice, Olson A. James, Shike Moshe and Ross A. Catharine eds. 9th edition

• Guyton, C. Arthur. 1985. Textbook of Medical Physiology. 6th edition, W.B. Company

Dr. Siham Gritly 66

• Lehninger. Principles of bochemistry. by Nelson and Cox, 5th Edition; W.H. Freeman and Company

• Emsley, John (2011). Nature's Building Blocks: An A-Z Guide to the Elements (New ed.). New York, NY: Oxford University Press. ISBN 978-0-19-960563-7.

• Koppenol, W. H. (2002). "Naming of New Elements (IUPAC Recommendations 2002)" (PDF). Pure and Applied Chemistry 74 (5): 787–791. doi:10.1351/pac200274050787. http://media.iupac.org/publications/pac/2002/pdf/7405x0787.pdf.