CLASSIFICATION OF POLYSACCHARIDES

A seminar onCLASSIFICATION OF POLYSACCHARDIES, GLUCONEOGENESIS, GLUCOGENOLYSISG. D. RUNGTA COLLEGE OF SCIENCE & TECHNOLOGY, KOHKA, BHILAI. BY:-1 Dr. ARUNIMA KARKUN ASST. PROFESSOR

CLASSIFICATION OF POLYSACCHARIDES, GLUCONEOGENESISGLYCOGENOLYSIS

INTRODUCTION

WHAT ARE POLYSACCHARIDES?

GENERAL CHARACTERSTICS OF POLYSACCHARIDES

CLASSIFICATION OF POLYSACCHARIDESHomopolysaccharidesHeteropolysaccharides

ROLE OF POLYSACCHARIDES

GLUCONEOGENESIS

GLYCOGENOLYSIS

SUMMARY

REFERENCES

SYNOPSIS2

CLASSIFICATION OF POLYSACCHARIDESAll organisms utilize carbohydrates important biomolecules.

Nutrition: carbos are more than just starch and sugar.

The term carbohydrate is derived from the french word: hydrate de carbone.

compounds composed of C, H, and O.

empirical formula: (CH2O)n.

Defination:- carbohydrate defined as polyhydroxyaldehyde or ketone which produce them on hydrolysis.

3INTRODUCTION

CLASSIFICATION OF POLYSACCHARIDES FUNCTION OF CARBOHYDRATES

Most abundant dietary source of energy (4 cal/g) for all organisms. Participate in the structure of cell membrane & cellular functions.Structural components of many organisms, include the fiber (cellulose) of Plants, exoskeleton of some insects.Storage of energy to meet the immediate energy demands of the body.

CLASSIFICATION OF CARBOHYDRATES

MONOSACCHARIDES- glucose, fructose. OLIGOSACCHARIDESDi, tri, tetra, penta, upto 9 or 10 Most important are the disaccharides-lactose, sucrose. POLYSACCHARIDES OR GLYCANSHomopolysaccharides-starch, glycogen, celluloseHeteropolysaccharides4INTRODUCTIONCONT.

CLASSIFICATION OF POLYSACCHARIDES Generally called glycans.Contains a number of monosaccharide units linked by glycosidic bonds.CHARACTERISTICS:Polymers (MW from 200,000).White and amorphous products (glassy)Not sweet.Not reducing; do not give the typical aldose or ketose reactions).Form colloidal solutions or suspensions.

5WHATAREPOLYSACCHARIDES? POLYSACCHARIDES

CLASSIFICATION OF POLYSACCHARIDESPOLYSACCHARIDES

HOMOPOLYSACCHARIDESHETROPOLYSACCHARIDES

CLASSIFICATION OF POLYSACCHARIDES Divided into two broad groups:

Homopolysaccharides-Contains only one type of monomer. On hydrolysis, they yield only one type of monosaccharide. Examples: Starch, cellulose, glycogenHeteropolysaccharides- Contain two or more types of monomers. On hydrolysis, they yield mixture of monosaccharides. Examples: hyaluronic acid, chondriotin sulphate, heparin, and mureins.

7CLASSIFICATION.CLASSIFICATION

Fig. no 1

CLASSIFICATION OF POLYSACCHARIDES 1. STARCHTwo forms: amylose , amylopectin.1,4-a-D-glucopyranose polymer.Function: plant glucose/energy storage.Hydrolysis glucopyranose.Easily digested by mammals.Natural starches contain 10-20% amylose and 80-90% amylopectin.a. Amylose - unbranched (1-4 ) 200 to 20 000 glucose units. Water soluble(15-20%).Stained blue by iodine.

8Homopolysaccharides-EXAMPLES

CLASSIFICATION OF POLYSACCHARIDES 9

Amylopectin - branched (1-4 ) + (1-6 ) Up to million glucose units.

Water insoluble amylopectin(80-82%).

Stained red-brown by iodine.

EXAMPLES-STRUCTURE NO .1STRUCTURE NO .2 CONT.

CLASSIFICATION OF POLYSACCHARIDES 2. GLYCOGEN The glucose storage polymer in animals, is similar in structure to amylopectin But glycogen has more a(16) branches. The highly branched structure permits rapid glucose release from glycogen stores, e.g., in muscle during exercise. The ability to rapidly mobilize glucose is more essential to animals than to plants10EXAMPLES

CONT.STRUCTURE NO .3

CLASSIFICATION OF POLYSACCHARIDES 3. CELLULOSE - nonbranched (1-4 )Insoluble, chemically very resistant. Major structural material of plants, wood, cotton.It is a major constituent of fiber.Cellulose is totally absent in animal.Composed of - D-glucose units linked by (1-4 ) glycosidic bonds.

11EXAMPLES

STRUCTURE NO . 4CONT.

CLASSIFICATION OF POLYSACCHARIDES 4.CHITIN N-acetyl-D-glukosamine a ( 1-4 )Structural polysaccharide of exoskeleton of invertebrates (in complex with proteins and/or CaCO3)

12EXAMPLES

5. PECTIN D-galakturonic acid a (1-4) Methylesters often side chains containing other monosaccharides.

Present in small fruits, plants.

STRUCTURE NO.5. STRUCTURE NO..6 CONT

CLASSIFICATION OF POLYSACCHARIDES 2.HETEROPOLYSACCHARIDES It is composed of a mixture of monosaccharides.On hydrolysis, they yield a mixture of monosaccharides.

HETEROPOLYSACCHARIDES - are further classified into two types:NEUTRAL SUGARS.MUCOPOLYSACCHARIDES .

NEUTRAL SUGARS.This group Includes some hemicellulose, some gums, mucilages & pectic substances. Give more than one type of sugar units on hydrolysis & sometimes non-sugar components .

13

CLASSIFICATION OF POLYSACCHARIDES 14MUCOPOLYSACCHARIDES .Mucopolysaccharides are heteroglycans made up of polysaccharides made up of repeating units of sugar derivatives, namely amino sugars & uronic sugar.

Commonly known as Glycosaminoglycans (GAG).

Mucopolysaccharides are essential components of tissue structure. Some Mucopolysaccharides are found in combination with proteins to form Mucoproteins or mucoids or proteoglycans . Mucopolysaccharides include hyaluronic acid ,heparin , dermatan sulfate, keratan sulfate.

CLASSIFICATION OF POLYSACCHARIDES 1.HYALURONATE (Hyaluronan) or Hyluronic acid.It is a glycosaminoglycan with a repeatingdisaccharide consisting of 2 glucose derivatives, glucuronate (glucuronic acid) & N-acetyl-glucosamine. The glycosidic linkages are (1-3) & (1-4).Hyaluronidase is an enzyme present in high concentration in testes, seminal fluid, in certain snake & insects that breaks (1-4) linkages.

15

EXAMPLESMUCOPOLYSACCHARIDESSTRUCTURE NO..7

CLASSIFICATION OF POLYSACCHARIDES 162. KERATAN SULFATE It is a heterogeneous GAG with a variable sulfate content, besides small amounts of mannose, fructose, sialic acid etc. It is essentially consists of alternating units of D- galactosamine and N-acetylglucasamine . They are present in cartilage, bone, cornea, nail, hoofs, claws.EXAMPLES

STRUCTURE NO.8CONT.

CLASSIFICATION OF POLYSACCHARIDES 173.HEPARIN Heparin is an anticoagulant (prevents blood clotting) that occurs in blood, lung, liver, kidney, spleen etc. Made in mast cell & released into the blood.

Heparin is composed of alternating units of N-sulfo D-glucosamine 6-sulfate & glucoronate 2-sulfate,EXAMPLES

STRUCTURE NO.9CONT.

CLASSIFICATION OF POLYSACCHARIDES 18

ROLE OF POLYSACCHARIDESTABLE NO .1

GLUCONEOGENESISDefinition: the biosynthesis of glucose primarily from pyruvate and its precursors.

The major substrates/precursors for gluconeogenesis are lactate, pyruvate, glucogenic amino acid, propionate & glycerol.

The liver is the major location for gluconeogenesis (about 1kg glucose synthesized everyday).

Gluconeogenesis occurs mainly in the Cytosol, although some precursors are produced in the Mitochondria.

This is essential cycle for the survival of humans and other animals. 19INTRODUCTION

GLUCONEOGENESISGluconeogenesis closely resembles the reversed pathway of glycolysis, although it is not the complete reversal of glycolysis.

Essentially, 3(out of 10) reactions of glycolysis are irreversible.

The 7 reactions are common for both glycolysis & Gluconeogenesis.

The 3 irreversible steps of glycolysis are catalysed by the enzymes, namely hexokinase , phosphofructokinase and pyruvate kinase.

These 3 stages- bypassed by alternate enzymes specific to Gluconeogenesis 20INTRODUCTION

GLUCONEOGENESIS21

CYCLE NO.1CONT.

GLUCONEOGENESISThese 3 stages- bypassed by alternate enzymes specific to Gluconeogenesis are below:- 1. Conversion of pyruvate to phosphophenol-pyruvate:This takes place in two steps Pruvate carboxylase is a biotin-dependent mitochondrial enzyme that converts Pruvate to oxaloacetate in presence of ATP & CO2.In the cytosol, phosphoenolpyruvate carboxykinase converts oxaloacetate to phosphoenolpyruvate.

2. Conversion of fructose 1,6-biphosphate to fructose 6-phosphate:Phosphophenolpyruvate undergoes the reversal of glycolysis until fructose 1,6-biphosphate is produced.

3. Conversion of Glucose 6-phosphate to Glucose: Glucose 6-phosphate catalyses the conversion of Glucose 6-phosphate to Glucose.

Glycolysis & Gluconeogenesis are both spontaneous. If both pathways were simultaneously active in a cell, it would constitute a "futile cycle" that would waste energy .

22REACTIONS

GLUCONEOGENESIS23

SEQEUENTIAL REACTIONS OF GLUCONEOGENESIS CHART NO.2CONT.

GLUCONEOGENESIS Overall summary of Gluconeogenesis for the conversion of pyruvate to glucose is shown below:-

Glycolysis: glucose + 2 NAD+ + 2 ADP + 2 Pi 2 pyruvate + 2 NADH + 2 ATP.

Gluconeogenesis: 2 pyruvate + 2 NADH + 4 ATP + 2 GTP +2H + glucose + 2 NAD+ + 4 ADP + 2 GDP + 6 Pi +6H +

24OVERALL SUMMARY

GLUCONEOGENESISIMPORTANCE OF GLUCONEOGENESIS :-

Brain, central nervous system, erythrocytes, testes & kidney medulla are dependent on glucose for continuous supply of energy.

In fasting even more than a day gluconeogenesis must occur to meet the basal requirements of the body.

Glucose is the only source that supplies energy to the skeletal muscle , under anaerobic conditions.

Certain metabolites produced in the tissues accumulate in the blood e.g lactate ,glycerol etc gluconeogenesis effectively clears them from blood.25IMPORTANCE

GLYCOGENOLYSISDEFINATION:-The degradation of stored glycogen in the liver and muscle constitutes GLYCOGENOLYSIS.

The pathways for the synthesis and degradation of glycogen are not possible are not reversible.

An independent set of enzymes present in the cytosol carry out glycogenolysis.

Glycogen is degraded by breaking -1,4- & -1,6-glycosidic bonds.

A good coordination & regulation of glycogen synthesis & its degradation are essential to maintain the blood glucose levels.

Glycogenesis & glycogenolysis are , respectively, controlled by the enzymes glycogen synthase & glycogen phosphorylase.26INTRODUCTION

GLYCOGENOLYSIS2.ACTION OF GLYCOGEN PHOSPHORYLASE:-

The -1,4-glycosidic bonds are cleaved sequentially by the enzyme glycogen to yield glucose 1-phosphate.This process is called phosphorolysis. The glycogen so formed is known as limit dextin which cannot be further degraded by phosphorylase.

2. ACTION OF DEBRANCHING ENZYME:

The branches of glycogen are cleaved by two enzyme activities present on a single polypeptide called debranching enzyme, hence it is a bifunctional enzyme.Amylo -1,4-glycosidase breaks the -1,6-bond at the branch with a single glucose residue and release a free glucose.

3.FORMATION OF GLUCOSE 6-PHOSPHATE AND GLUCOSE:

Through the combined action of glycogen phosphorylase and debranching enzyme glucose 1-phosphate & free glucose in a ratio of 8:1 are produced .Glucose 1-phosphate is converted to glucose 6-phosphate by the enzyme phosphoglucomutase.

27REACTIONS

GLYCOGENOLYSIS28

CYCLE NO.2*

GLYCOGENOLYSISGlycogen is the storage form of glucose.

The degradation of glycogen (glycogenolysis) in muscle meets the immediate fuel requirements.

On the other hand the liver glycogen maintains the blood glucose level.

Enzymes defects in synthesis or the degradation of glycogen leads to storage disorders.

Von Gierkes disease is due to the defect in the enzyme glucose 6- phosphatase .29IMPORTANCE

SUMMARYCarbohydrates are the polyhydroxyaldhyde or ketones or compounds which produce them on hydrolysis .

Carbohydrates are broadly classified into three groups:-MONOSACCHARIDES,OLIGOSACCHARIDES,POLYSACCHARIDES.

Polysaccharides are the polymers of monosaccharides on their derivative, held together by glycosidic bonds.

Polysaccharides are broadly classified into two groups:- (A)Hompolysaccharides (B)Heteropolysaccharides

The biosynthesis of glucose primarily from pyruvate and its precursors is known as gluconeogenesis.

The degradation of stored glycogen in the liver and muscle constitutes glycogenolysis.

30SUMMARY

CLASSIFICATION OF POLYSACCHARIDES , GLUCONEOGENESIS, GLYCOGENOLYSISPolysaccharides play important role in structure & storage for plants.

Polysaccharides are also help in cell envelope development in bacteria.

Polysaccharides provides exoskeleton in spiders & insects.

In fasting even more than a day gluconeogenesis must occur to meet the basal requirements of the body.

Glucose is the only source that supplies energy to the skeletal muscle , under anaerobic conditions.

Certain metabolites produced in the tissues accumulate in the blood e.g lactate ,glycerol etc gluconeogenesis effectively clears them from blood.

Glycogenolysis supplies energy to muscles & other body parts.

31CONCLUSION

CLASSIFICATION OF POLYSACCHARIDES , GLUCONEOGENESIS, GLYCOGENOLYSISALBERT L. LEHNINGER YEAR -2005BIOCHEMISTRY,2ND EDITION, FREEMAN PUBLICATION.L. NELSON & M. COX YEAR -2009PRINCIPLES OF BIOCHEMISTRY, 5TH EDITION,STUTTGAT PUBLICATION.J. L. JAIN YEAR -2010PRINCIPLES OF BIOCHEMISTRY,6TH EDITION,S.CHAND PUBLICATION.U.SATYANARAYANA , U.CHAKRAPANI YEAR -2010BIOCHEMISTRY,6TH EDITION,UPPALA PUBLICATION.

32REFERENCESOTHER SOURCES- WEB LINKS

33THANK YOU

EMBED ChemDraw.Document.4.5

glycogen

_995972862.cdx

_995973151.cdx

_995972609.cdx

EMBED ChemDraw.Document.4.5

hyaluronate

_1020239213.cdx

_1020239613.cdx

_1052598329.cdx

_1052599108.cdx

_1020239474.cdx

_1020238536.cdx

_1020238608.cdx

_1020238345.cdx