1. Polysaccharides
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2. Polysaccharides Polysaccharides are complex carbohydrates made up
linked monosaccharide units.
Nomenclature:
Homopolysaccharide-a polysaccharide is made up of one type of monosaccharide unit
Heteropolysaccharide-a polysaccharide is made up of more than one type of monosaccharide unit
Starch and glycogen are storage molecules
Chitin and cellulose are structural molecules
Cell surface polysaccharides are recognition molecules
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3. Sources of Polysaccharides
Microbial fermentation
Higher plants
seeds
tree extrudates,
marine plants,
Chemical modification of other polymers
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4. Some types of polysaccharides
1.Starch
Starch is a storage compound in plants, and made of glucose units
It is a homopolysaccharide made up of two components: amylose and amylopectin.
Most starch is 10-30% amylose and 70-90% amylopectin
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5. Structure of Amylose Fraction of Starch
Amylose – a straight chain structure formed by 1,4 glycosidic bonds between α-D-glucose molecules.
Structure of Amylose Fraction of Starch
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6. The amylose chain forms a helix.
This causes the blue colour change on reaction with iodine.
Amylose is poorly soluble in water, but forms micellar suspensions
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7. Amylopectin --- a glucose polymer with mainly α -(14) linkages, but it also has branches formed by α -(16) linkages. Branches are generally longer than shown above.
Structure of Amylopectin Fraction of Starch
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8. Amylopectin causes a red-violet colour change on reaction with iodine.
This change is usually masked by the much darker reaction of amylose to iodine.
Amylopectin
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9. Starch therefore consists of amylose helices entangled on branches of amylopectin.
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10. 2. Glycogen Storage polysaccharide in animals
Glycogen constitutes up to 10% of liver mass and 1-2% of muscle mass
Glycogen is stored energy for the organism
Similar in structure to amylopectin, only difference from starch: number of branches
Alpha(1,6) branches every 8-12 residues
Like amylopectin, glycogen gives a red-violet color with iodine
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11. 3. Cellulose
The β-glucose molecules are joined by condensation, i.e. the removal of water, forming β-(1,4) glycosidic linkages.
Note however that every second β -glucose molecule has to flip over to allow the bond to form. This produces a “heads-tails-heads” sequence.
The glucose units are linked into straight chains each units long.
Weak hydrogen bonds form between parallel chains binding them into cellulose microfibrils.
Cellulose microfibrils arrange themselves into thicker bundles called microfibrils. (These are usually referred to as fibres.)
The cellulose fibres are often “glued” together by other compounds such as hemicelluloses and calcium pectate to form complex structures such as plant cell walls.
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12. Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

13. Cellulose
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14. Heteropolysaccharides
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15. Mucosubstance
Mucosubstance formed sticky or viscous solutions in the body.
They are divided in to 2 groups.
1. Glycoproteins
2. Mucopolysaccharides
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16. Glycoproteins
They are protein polysaccharide compound occouring in the tissues, perticularly in mucus secretions.
They containing hexoxamine such as N-acetylglucosamine & N- acetylgalactosamine.
Haxoses such as mannose or galctose are found.
They formed viscous solutions such are used as lubricants & protective “Screens” in the body.
eg, continuously Mucus secretion from respiratory tract is protects against bacteria.
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17. Hetropolysaccharides OR Mucopolysaccharides
Chondrotin Sulphate
They generally forms in tissues like Skin.
Chondrotin Sulphate A & C consists of alternate uniTs of glucuronic acid & N-acetylamino galactose.
Chondrotin Sulphate B contains iduronic acid in place of glucuronic acid.
In all 3 forms, 1 –OH (hydroxyl group) of each amino sugar is esterified with sulphuric acid & formed a long chain.
They are anions, helps to regulate the flow & concentrations of cations around cells.
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18. Hyaluronic acid It has a M.W of 1-4 million
It consist of alternate unit of glucuronic acid & N-acetylglucosamine linked to give a thread-like structure.
It forms viscous solution in water and is imortant in the body as a lubricant.
It has enormous capacity to hold water.
It occurs in synovial fluid, in the skin.
Its presence affects the rate of diffusion of materials in the skin.
The enzyme hyaluronidase reduces its viscosity and helps in diffusion in tissue space.
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19. Hyaluronidase rate of diffusion of substances through tissue containing Hyaluronic acid. - Hyaluronidase generally presents in mammals testis and it helps in fertilization process.
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20. Heparin Its occurs in moist cells and is present in liver and lungs.
It consist of unbranched chain of alternate units of glucosamine and glucuronic acid joined mainly by 1,4-α-links.
Sulphate groups are linked to the hydroxyl group of carbon atom 6 and the aminogroup of the glucosamine and glucuronic acid units.
Its M.W is about 17,000 and its highly sulphated.
Its used in medicine as an anticoagulant.
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21. Blood group Substance Keratosulphate
They consists of N-acetylglucosamine, galctosamine, glactose and sialic acids.
They are used to determine blood group.
Keratosulphate
They consists of N-acetylglucosamine, glactose, Sulphuric acids.
It is component of cornea & cartilage.
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22. Dextrins
They are formed by hydrolysis of starch by an enzyme, mineral acids or heat.
eg, The final product of hydrolysis of starch by an amylase is maltose which is hydrolysed by glucose.
Amylodexrins & erythrodextrins gives red or blue color when reacts with iodine.
If they have reducing properties, they are very feeble.
They have sweet taste.
They form sticky solutions in water & are frequently used as adhesive.
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23. Inulin It is found in tubers & roots of dahlias & dandelions.
It is hydrolysed by fructose.
It;s does not produced any color with iodine.
It is easily soluble in warm water.
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24. KILIANI-FISCHER SYNTHESIS
A method for synthesis of monosaccharides was first proposed by Kiliani.
It is based upon the addition of HCN to the carbonyl group of aldehyde or ketones.
The application of the kiliani synthesis to the production of
2 tetroses--- Erythrose & Threose from glycerose .
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25. Kiliani-fischer synthesis: the method of lengthening the carbon chain
of the an aldose.
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26. Polysaccharides by Mrs. Chakshuta Gandhi (SOS)