AMITY UNIVERSITY, KOLKATA

NAME- MAINAK CHAKRABORTY

PROGRAM- B.Tech (BIOTECHNOLOGY)

COURSE NAME- Term PaperCOURSE CODE- BTTP100

TOPIC- BIOMACROMOLECULE POLYSACCHARIDES

MENTOR- Dr. ANIRBAN RAY

ENROLLMENT No.- A91704115037 YEAR- 2015-’19

INTRODUCTION: Polysaccharide is a kind of Carbohydrate.A carbohydrate is a biological molecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water); in other words, with the empirical formula Cm(H2O)n (where m could be different from n). Some exceptions exist; for example, deoxyribose, a sugar component of DNA, has the empirical formula C5H10O4. Carbohydrates are technically hydrates of carbon; structurally it is more accurate to view them as polyhydroxy aldehydes and ketones. Carbohydrates are the main sources of strength in any living organism. DEFFINATION:Optically active, polyhydroxy aldehydes and ketones or those components which give polyhydroxy aldehydes and ketones by hydro-synthesis, those are called Carbohydrates• Carbohydrates have many uses in our daily life, like—1. Most of our daily foods contain carbohydrate like ‘starch’.2. Linen, rayon which are the raw materials for textile industries

are made of cellulose etc.

Figure 1Lactose is a disaccharide

 found in milk. It consists of a molecule of D-galactose and a molecule of D-glucose bonded by beta-1-4 glycosidic linkage

Basically carbohydrates are two types— SUGAR: Those carbohydrates which are colloidal, sweet in

taste & soluble in water are called sugar carbohydrates. Monosaccharides & Oligosaccharides are sugar carbohydrates. E.g. Glucose, Fructose etc.

NON-SUGAR: Those carbohydrates which are non-colloidal, not sweet in taste & insoluble or semi-soluble in water are called non-sugar carbohydrates. Polysaccharides are non-sugar carbohydrates. E.g. Starch, Cellulose etc.

  Classification of carbohydrates:1) Monosaccharides (monoses or glycoses): Trioses, Tetroses, Pentoses, Hexoses2) Oligosaccharides: Di, tri, tetra, penta, up to 9 or 10 most important are the disaccharides 3) Polysaccharides or glycans: a) Homopolysaccharides, b) Heteropolysaccharides 

As it is adhered by the supervisor, that I have to make a project on Chemistry of Polysaccharides, so it is underneath:

POLYSACCHARIDES: Polysaccharides (Polymeric Carbohydrate Molecule) are Natural Condensation Polymer composed of long chain of Monosaccharides.

Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit. Depending on the structure, these macromolecules can have distinct properties from their monosaccharide building blocks. They may be amorphous or even insoluble in water. When all the monosaccharides in a polysaccharide are the same type, the polysaccharide is called a homopolysaccharide or homoglycan, but when more than one type of monosaccharide is present they are called Heteropolysaccharides or Heteroglycans . When the repeating units in the polymer backbone are six-carbon Monosaccharides, the general formula simplifies to (C6H10O5) n Characteristics:

1. Polymers (MW from 200,000).2. White and amorphous products (glassy).3. Not sweet.4. Not reducing; do not give the typical aldose or ketose reactions.5. Form colloidal solutions.

Figure 2: A Beta-Glucan Polysaccharide. 

Mainly Polysaccharides are two types-

1. Homosaccharides: These polymers composed of a single type sugar monomers. These carbohydrates are three types-

Glucosan: Starch, Glycogen etc. Fructosan: Inulin Galactosan: Agar

2. Heterosaccharides: The Disaccharides usually contains an Acid sugar (D- Glucuronic acid or its C5 epimer Iduronic acid) and an Amino sugar (the amino sugar may be sulfated on non-acetylated Nitrogen). E.g. Hyaluronic acid.

We can also classify Polysaccharides by their work, like-

1. Storage Polysaccharides:

Starch [(C6H10O5)n] : -Most common storage polysaccharide in plants-Composed of 10 – 30% Amylose and 70-90% Amylopectin depending on the source

(a) Amylose is a linear polymer of α-D-glucose, linked together by α 1→4 glycosidic linkages. It is soluble in water, reacts with iodine to give a blue color and the molecular weight of Amylose ranges between 50, 000 – 200, 000.

(b) Amylopectin is a highly branched polymer, insoluble in water, reacts with iodine to give a reddish violet color. The molecular weight ranges between 70, 000 - 1 000, 000. Branches are composed of 25-30 glucose units linked by α 1→4 glycosidic linkage in the chain and by α 1→6 glycosidic linkage at the branch point.

Suspensions of Amylosein water adopt a helical conformationIodine (I2) can insert in the middle of the Amylosehelix to give a blue colorthat is characteristic and Figure 3: Suspensions of

Amylose in water adopt a helical conformation 

diagnostic for starch

Starch can be hydrolysed into simpler carbohydrates by acids, various enzymes, or a combination of the two. The resulting fragments are known as dextrin. The extent of conversion is typically quantified by dextrose equivalent (DE), which is roughly the fraction of the glycosidic bonds in starch that have been broken.These starch sugars are by far the most common starch based food ingredient and are used as sweetener in many drinks and foods. They include:• Maltodextrin, a lightly hydrolysed (DE 10–20) starch product used as a bland-

tasting filler and thickener.

• Various glucose syrups (DE 30–70), also called corn syrups in the US, viscous solutions used as sweeteners and thickeners in many kinds of processed foods.

• Dextrose (DE 100), commercial glucose, prepared by the complete hydrolysis of starch.

• High fructose syrup, made by treating dextrose solutions with the enzyme glucose isomerase, until a substantial fraction of the glucose has been converted to fructose. In the United States sugar prices are two to three times higher than in the rest of the world, which makes high fructose corn syrup significantly cheaper, so that it is the principal sweetener used in processed foods and beverages. Fructose also has better microbiological stability. One kind of high fructose corn syrup, HFCS-55, is sweeter than sucrose  because it is made with more fructose, while the sweetness of HFCS-42 is on par with sucrose.

• Sugar alcohols, such as maltitol, erythritol, sorbitol, mannitol and hydrogenated starch hydrolyse, are sweeteners made by reducing sugars.

 

Significance-

Glycogen [C24H42O21]:-Also known as animal starch-Stored in muscle and liver-Present in cells as granules (high MW)-Contains both α(1,4) links and α (1,6) branches at every 8 to 12 glucose unit-Complete hydrolysis yields glucose- With iodine gives a red-violet color-Hydrolyzed by both α and β-amylases and by glycogen phosphorylase

Significance- -In the liver, glycogen synthesis and degradation are regulated to maintain blood-glucose levels as required to meet the needs of the organism as a whole. Glycogen serves as a buffer to maintain blood glucose level.

-In contrast, in muscle, these processes are regulated to meet the energy needs of the muscle itself.

- The concentration of glycogen is higher in the liver than in muscle (10% versus 2% by weight), but more glycogen is stored in skeletal muscle overall because of its much greater mass.

Figure 4: Structure of Glycogen

Figure 5 Jerusalem artichokes

Inulin: -b-(1,2) linked fructofuranoses-Linear ,no branching

-Lower molecular weight than starch-Colors yellow with iodine-Hydrolysis yields fructose-Sources include onions, garlic, dandelions and Jerusalem artichokes-Used as diagnostic agent for the evaluation of glomerular filtration rate (renal function test)

Significance- -used clinically as a highly accurate measure of glomerular filtration rate (GFR) -Used as a soluble dietary fiber-Used as appetite suppressant-Used as a low glycemic index sweetener-Also used as a fat/cream substitute

2. Structural Polysaccharides:

Cellulose [(C6H10O5)n]: -Polymer of b-D-glucose linked by b(1,4) linkages-Yields glucose upon complete hydrolysis-Partial hydrolysis yields cellobiose-Most abundant of all carbohydrates-Gives no color with iodine-Cellulose is tasteless, odorless and insoluble in water and most organic solvents.  Significance—Microcrystalline cellulose: used as binder- disintegrant in tablets-Methyl cellulose: suspending agent and bulk laxative-Oxidized cellulose: hemostat-Sodium carboxymethyl cellulose: laxative-Cellulose acetate: rayon; photographic film; plastics-Cellulose acetate phthalate: enteric coating-Nitro cellulose: explosives; collodion (pyroxylin)

Figure 4: Structure of Cellulose

Chitin: -Chitin is the second most abundant carbohydrate polymer of N- Acetyl Glucosamine-present in the cell wall of fungi and in the exoskeletons of crustaceans, insects and spiders

Figure 6 Structure of Chitin

-chitin is used commercially in coatings (extends the shelf life of fruits and meats.

Pectin :Pectin is a family of complex polysaccharides that contain 1,4-linked α-D-galacto syluronic acid residues. They are present in most primary cell walls and in the non-woody parts of terrestrial plants. a

Significance• Main use as gelling agent (jams, jellies)

dependent on degree of methylationhigh methoxyl pectin gel through H-bonding and in presence of sugar and acidlow methoxyl pectin gel in the presence of Ca2+ (‘egg-box’ model)

• Thickeners• Water binders• Stabilizers

Figure 8 Structure of Pectin

3. Acidic Polysaccharides: Acidic polysaccharides are polysaccharides that contain carboxyl groups, phosphate groups and/or sulphuric ester groups

Hyaluronic acid (D-glucuronate + GlcNAc)n- Occurrence: synovial fluid, ECM of loose connective tissue. Serves as a lubricant and shock absorber.-Hyaluronic acid does not contain any sulfate and is not found covalently attached to proteins. -It forms non-covalently linked complexes with Proteoglycans in the ECM.-Hyaluronic acid polymers are very large (100 - 10,000 kDa) and can displace a large volume of water.

Figure 9 Structure of Hyaluronic Acid

Dermatan sulphate (L-Iduronate + GalNAc sulfate) n :

Occurrence: skin, blood vessels, heart valves

Chondroitin sulphate (D-glucuronate + GalNAc sulfate)n :Occurrence: cartilage, tendons, ligaments, heart valves and aorta. It is the most abundant GAG.

Figure 11 Dermatan SulfateFigure 10 Chondroitin

Sulfate

Pathogenic bacteria commonly produce a thick, mucous-like, layer of polysaccharide. This "capsule" cloaks antigenic proteins on the bacterial surface that would otherwise provoke an immune response and thereby lead to the destruction of the bacteria. Capsular polysaccharides are water-soluble, commonly acidic, and have molecular weights on the order of 100-2000 kDa.

3. Bacterial

Polysaccharides:

Dextran: -Products of the reaction of glucose and the enzyme Transglucosidase from Leuconostoc

mesenteroides

-Contains α (1,4), α(1,6) and α (1,3) linkages-MW: 40,000; 70,000; 75,000-Used as plasma expanders (treatment of shock)-also used as molecular sieves to separate proteins and other large molecules (gel filtration chromatography)

Xanthan :

Source: Product of bacteria Xanthomonas campestris

Structure: cellulose-like backbone (b-1,4-poly-glucose) with trisaccharide

branches (stubs) on alternate monomers on the backbone carrying

carboxylic acid residue Significance:- Double helical conformation- Pseudo plastic- Shear-thinning- Thickener- Stabilizer- Emulsifier- Foaming agent- Forms synergistic gels with galactomannans- Water soluble, viscous, non-gelling. Viscosity is only slightly temperature

dependent

Figure 12 Structure of Xanthan Gum

SUMMARY Homopolysaccharides are polymers of similar monomer monosaccharides linked together by Glycosidic linkages. Structurally they may be Glucosan, Fructosan or Galactosan. Functionally they may be storage, structural, acidic or bacterial polysaccharides Heteropolysaccharides are polymers of repeating disaccharide units with enormous diversity. They are components of ECM, joints, cartilages, tendons, cornea and sclera. Heparin is an anticoagulant

Mainak Chakraborty