Carbohydrate 2 Di-Poly

8/10/2019 Carbohydrate 2 Di-Poly

1/22

7P2-1

March 5, 2013

CARBOHYDRATE METABOLISM

Structure


2/22

7P2-2

Di and oligosaccharides

Polysaccharides

Homo and heteropolysaccharides

Glycoconjugates

Outline


3/22

7P2-3

Disaccharides: Sucrose

Sucrose is formed by linking D-glucose withb

D-fructose to give a 1,2glycosidic link.

CH2

O H

OH H

OH

O H

CH2

OH

OHO

CH2OH

HH

OH

H

OH

OH

H

H1 2


4/22

7P2-4

Disaccharides: Lactose

Lactose is formed by joiningb

D-

galactose to D-glucose to give a 1,4glycoside

O

CH2OH

H

H

OH

H

OH

OH

H H OH

O

CH2OH

HH

H

OH

OH

H

H

O1

b

D-galactose

4

D-glucose


5/22

7P2-5

Disaccharides: Maltose

Maltose is formed by linking two -D-

glucose molecules to give a 1,4glycosidic link.

OH

O

CH2OH

HH

H

OH

OH

H

H

O

O

CH2OH

HH

OH

H

OH

OH

H

H

4-O-a-D-glucopyranosyl-a-D-glucopyranose

14


6/22

7P2-6

Oligosaccharide

An oligosaccharide is a saccharide polymer

containing a small number (typically three toten of component sugars, also known assimple sugars. The name derived from the

Greek ol igos , meaning "a few".

Fructo-oligosaccharides (FOS), which are

found in many vegetables, consist of shortchains of fructose molecules. Inulin has amuch higher degree of polymerization thanFOS and is a polysaccharide


7/227P2-7

Oligosaccharide

Fructooligosaccharides (FOS) alsosometimes called oligofructose oroligofructan, is a class of

oligosaccharides used as an artificialor alternative sweetener

Two different classes of FOS mixturesare produced commercially, based oninulin degradation or processes


8/227P2-8

Oligosaccharide-Inulin

Inulins are a group of naturally occurringpolysaccharides (several simplesugars linked together) produced bymany types of plants. They are belong

to a class of fibers known as fructans.Inulin is used by some plants as ameans of storing energy and is

typically found in roots or rhizomes.Most plants which synthesize and storeinulin do not store other materials such

as starch


9/227P2-9

Polysaccharides: Cellulose

Cellulose is the major structural

polymer in plants. It is a linerhomopolymer composed of bD-glucose units linked

b

-1,4. The

repeating disaccharide of celluloseis b-cellobiose.

Animals lack the enzymes

necessary to hydrolyze cellulose.The bacteria in ruminants (eg.cows) can digest cellulose so that

they can eat grass, etc.


10/227P2-10

Polysaccharides: Starch

Starches are storage forms of glucose

found in plants.They are polymers of linked glucose.If the links are only 1,4, the polymer is

linear and is called amylose.Amylose usually assumes a helical

configuration with six glucose units

per turn.If the links are both 1,4 and 1,6, thepolymer is branched and is calledamylopectin.


11/227P2-11

Polysaccharides: amylose/amylopectin

O

O

CH2

OH

HH

H

OH

OH

H

H

O

O

CH2

OH

HH

O

H

OH

OH

H

HO

CH2

OH

HH

H

OH

OH

H

H

O

O

CH2

OH

HH

O

H

OH

OH

H

H

amylose

O

O

CH2

OH

HH

H

OH

OH

H

H

O

O

CH2

HH

O

H

OH

OH

H

HO

CH2

OH

HH

H

OH

OH

H

H

O

O

CH2

OH

HH

O

H

OH

OH

H

H

O

O

CH2

OH

HH

H

OH

OH

H

H

O

O

CH2

OH

HH

O

H

OH

OH

H

H Amylopectin

1,6 link at branch


12/227P2-12

Polysaccharides: glycogen

The storage carbohydrate in animalsis glycogen. It is a branched chain

polymer like amylopectin but it hasmore frequent branching (aboutevery 10 residues). Glycogen isstored in liver and muscle cells.


13/22

7P2-13

Polysaccharides

Bacterial cell walls haveheteropolysaccharides as majorcomponents.

The polymers consist of chains ofalternating N-acetyl-

b

-D-glucosamine

and N-acetylmuramic acid (next slide).The parallel chains are linked by shortpeptide residues.


14/22

7P2-14

Polysaccharides

O

CH2OH

HH

OH

H

O

NH

HH

OH

C CH3O

CHCH3COO

-

N-acetyl muramic acid


15/22

7P2-15

Glycoconjugates

Glycoconjugates are compounds that

covalently link carbohydrates toproteins and lipids.

Proteoglycans and glycoproteins are

two kinds of glycoconjugates thatcontain protein.

Proteoglycans:

Proteoglycans have a very highcarbohydrate to protein ratio, often

95:5, and are found in the extracellularmatrix.


16/22

7P2-16

Glycoproteins

These materials contain carbohydrateresidues on protein chains.

Important examples of glycoprotein areantibodies-chemicals which bind toantigens and immobilize them.

The carbohydrate part of theglycoprotein plays a role indetermining the part of the antigen

molecule to which the antibody binds.


17/22

7P2-17

Glycoproteins:

The human blood groups A, B, AB,and O depend on theoligosaccharide part of the

glycoprotein on the surface oferythrocyte cells.

The terminal monosaccharide of theglycoprotein at the nonreducingenddetermines blood group.


18/22

7P2-18

Glycoproteins:

Type Terminal sugarA N-acetylgalactosamine

B a-D-galactoseAB both the above

O neither of the above

O is the universal donor

AB is the universal acceptor


19/22

7P2-19

Sugars which are capable to reduce theoxidizing agents such as Tollen

reagents(AgO), Fehling reagents(CuO)called the Reducing Sugars.

Examples: glucose, fructose, maltose,lactose etc

Reducing and Nonreducing Sugar


20/22

7P2-20

Reducing sugar

A reducing sugar is any sugar that, in basic

solution, forms some aldehyde or ketone.

This allows the sugar to act as a reducing

agent, for example in the Maillard reactionand Benedict's reaction.

Those sugar which are unable to reducethe such above oxidizing agents iscalled the Non-reducing sugars.

Examples: Sucrose, Trehalose


21/22

7P2-21

Maillard Reaction:

The Maillard reaction is a chemical reactionbetween an amino acid and a reducing

sugar. Like caramelization (is the oxidationof sugar), it is a form of non-enzymaticbrowning

-This reaction is the basis of the flavoringindustry, since the type of amino aciddetermines the resulting flavor.


22/22

7P2-22

The End

Carbohydrates II

Documents

Carbohydrate 2 Di-Poly