Polysaccharides Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

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 Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

Sources of Polysaccharides Microbial fermentation Higher plants seeds tree extrudates, marine plants, Chemical modification of other polymers Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

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 Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

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 Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

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 Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

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 Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

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 Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

Starch therefore consists of amylose helices entangled on branches of amylopectin. Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

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 Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

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 100-1000 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. Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

Cellulose Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

Heteropolysaccharides Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

Mucosubstance Mucosubstance formed sticky or viscous solutions in the body. They are divided in to 2 groups. 1. Glycoproteins 2. Mucopolysaccharides Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

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. Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

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. Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

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. Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

Hyaluronidase rate of diffusion of substances through tissue containing Hyaluronic acid. - Hyaluronidase generally presents in mammals testis and it helps in fertilization process. Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

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. Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

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. Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

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. Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

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. Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

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 . Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

Kiliani-fischer synthesis: the method of lengthening the carbon chain of the an aldose. Polysaccharides by Mrs. Chakshuta Gandhi (SOS)

Polysaccharides by Mrs. Chakshuta Gandhi (SOS)