Carbohydrates Carbohydrates :: Physical and Chemical PropertiesPhysical and Chemical Properties

ByBy

drg. Prasetyo Adi, MSdrg. Prasetyo Adi, MS

ObjectivesTo Understand :• The importance of carbohydrates for

organisms• The classification of carbohydrates• The physical and chemical

properties of carbohydratesReference :• March and Bettelheim,1995;

Introduction to General,Organic & Biochemistry, 4th edition, Saunders College

What’s carbohydrate ?

• Compound containing C, H, O

• General formula : Cx (H2O)y

• Polyhydroxylated aldehydes aldose

• Polyhydroxylated ketones ketose

• In plants, simple carbohydrate (glucose) is synthesized from carbon dioxide and water by photosynthesis

CARBOHYDRATES:

• POLYHYDROXY ALDEHYDES OR KETONES

• SIMPLE CARBOHYDRATES MOLECULES ARE SYNTHESIZED

CHIEFLY BY CHLOROPHYL-CONTAINING PLANTS AS LONG

AS THE SUN IS SHINING

6 CO2 + 6 H2O C6H12O6 + 6 O2 LIGHT

KHOLOROFIL

PHOTOSYNTHESIS

The Importances of carbohydrates

• Give structure to cell walls and cell membrane (e.g. cellulose)

Humans:• Provide the majority of energy • A source of carbon atoms for

synthesis of many compounds nucleic acids and connective

tissue• Comprise large portions of nucleic

acids that form DNA and RNA (e.g. ribose, deoxyribose)

• Comprise some portions of connective tissues

Classification

Based on :

1. Number of sugar units in total chain

2. Number of carbon atoms in the chain

3. Stereochemistry

Classification of carbohydrate based on the number of sugar units :

• Monosaccharides : single sugar unit

e.g. glucose, fructose, galactose• Disaccharides : 2 sugar units

e.g. lactose, sucrose• Oligosaccharides : 3-10 sugar units

e.g. maltotriose• Polysaccharides : > 10 sugar units

e.g. starch, cellulose

Monosaccharides classifisation based on the number of carbon atoms

Stereoisomer

• Stereochemistry : study of the spatial arrangement of the molecules

• Stereoisomers have :

- the same order and types of bonds

- different spatial arrangements

- different properties

• Many biologically important chemicals, like sugars, exist as stereoisomers.

Enantiomers

• Pairs of isomers (stereoisomers)

• that are nonsuperimpossable mirror images of each other

• It must have at least 1 assymmetric carbon

( a chiral carbon)

H

C

FOH

Br

CH3CH2 CH3CH2

BrBr

H H

Mirror

CH3CH2

Br

H

CH3CH2

H

Br

HH

H

H

a non chiral C

CH3

CH3CH2 CH3CH2

CH3 Br

Br

H H

Mirror

CH3CH2

CH3

Br

H

CH3CH2

CH3

H

Br

Chiral C

Functional groups

Double bond

Hydroxyl

Carbonyl

Carboxyl

Sulfhidril

Amine

C C

OH

C O

C

O

OH

SH

NH2

C

CH OH

CH OH

OH

H

D(+) GLISERALDEHID

H2C

C

CH OH

OH

H

DI HIDROKSIASETON

O

Aldehyde ( aldose ) derivates :

C

CH OH

CH OH

O

H

HD(+) GLISERALDEHID

C

CH OH

C

CH2OH

H OH

C

CHO H

C

CH2OH

H OH

O O

H H

D(-) ERITHROSE D(-) THREOSE

C

C

C

C

C

C

CH OH

C

C

H OH

O

H

CH2OH

OHH

C

CHO

C

C

H OH

O

H

CH2OH

OHH

C

C

C

C

O

H

CH2OH

OHH

C

CH OH

C

C

HO H

O

H

CH2OH

OHH

H H

HHO

HO

D-RIBOSE D-ARABINOSE D-XILOSE D-LIXOSE

C

C C

C CC

C

C

C

C

C

C

D - Alosa

D - Altrosa

D - Glukosa

D - Manosa

D - Gulosa

D - Idosa

D - Galaktosa

D - Talosa

Structure of carbohydrates

• Open Chain Forms • Cyclic Forms

OH

OH

H

OHH

OH

CH2OH

HH

OH

Glucose

PHYSICAL PROPERTIES OF MONOSACCHARIDES

• sweetness

• solubility

• optical rotation

Table. Comperative Sweetness of Some Sugars and Artificial Sweeteners.

Sugar or Artificial Sweetness Type

Sweetener Relaitive to Sweeteners

Lactose 0,16 Disaccharide

Galactose 0,32 Monoccharide

Maltose 0,33 Disaccharide

Glucose 0,74 Monoccharide

Sucrose 1,00 Disaccharide

Invert sugar 1,25 Mixture of Glucose and Fructose

Fructose 1,74 Monoccharide

Aspartame 100 –150 Artificial sweetener

Acesulfame-K 200 Artificial sweetener

Saccharin 450 Artificial sweetener

Solubility

• At room temperature : carbohydrates are solids• Because of the many –OH groups as well as the oxygen

of the aldehyde or ketone groups carbohydrates are soluble in water

these groups form hydrogen bonds with the solvating water molecules

Optical Rotation

• All three forms of D-glucose (alpha, beta, and open-chain) rotate the plane of polarized ligth to the right D-(+)-glucose

• L-glucose rotate the plane of polarized ligth to the left L-(-)-glucose

• There is no simple relationship between configuration and rotation

• D-(+)-glucose = dextrose• D-(-)-glucose = levulose

CHEMICAL PROPERTIES OF MONOSACCHARIDES

• Cyclic forms

• Oxydation

• Glycoside formations

C

CH

C

C

HO

OH

D(+) Glucose

C

OH

H

OH

OH

CH2OH

H

H

CH2OH

C

C

C

HO

C

O

H

OH

OH

CH2OH

H

H

D-Fructose

O H

OH

H

OH

H

OH H

OH

CH2OH

H

OH

CH2OH

H

CH2OH

OH H

H OH

O

Pyranose Furanose

C

H

OH

H

OHH

OH

H

HO

CH2OH

O

H Rotate C4 - C5

OH

OH

H

OHH

OH

CH2OH

H

C

OHH

OH

H

OHH

OH

CH2OH

HO

H

H

OH

O

OH α

β

O

OH

Oxidation

• All of monosaccharides are reducing sugars

• Aldehydes and –OH groups are easily oxidized

• Aldehydes are oxidized to carboxylic acids

Dissaccharides • 2 units of monosaccharides

• Glycoside bonds • From carbon 1 to - OH groups (C4 position).

• α or β position from C1 of 1st unit 1 to –OH group C4 of 2nd unit

1,4’- α or 1,4’- β linkage

O

H

HO

H

HO

H

H

OHHO

OH

O

H

H

HO

H

OHH

OH

OH

12

4

3

5

6

4

3

5

6

21

1,4’- β linkage

Maltose.• It is a dissaccharide

• Contains 2 glucose units connected in a 1 4 linkage, from hydrolisis of starch by enzymes/acid

• Ex. : • Enzyme α 1,4 - glukan 4- glucanohydrolase in saliva • Enzyme α 1,4 - glukan maltohydrolase in malt

1 Maltose α - glukosidase 2 D-Glucose

O

H

HO

H

HO

H

OHH O

H

O

H

HO

H

OHH OH

H

HOH2C

HOH2C1

2

3

54

6

4

32

1

5

6

1,4’- linkage

Cellubiose • A dissaccharide

• From hydroliysis of cellulose by enzyme β-glukosidase

• Connected by 1,4 β glycoside linkage

• Cellubiose hydroliysis with acid produces α and β-D-glucose

OHO

H

HO

H

OHH

O

H

HO

H

OHH OH

O

HOH2C HOH2CH

H

H

Lactose• A dissaccharide

• Connected by 1,4 β glycoside linkage

• Lactose hydrolysis D - glucose and D - galactose,

D - glucose • Source : * mammalian milk 5% Lactose

O

OH

H

H

HO

H

H

OHH

HOH2CO

H

O

H

HO

H

OH

OHH

HOH2C

H

Sucrose.• Contains : glucose and fructose.

• The glycoside linkage is from C-1 of D-glucose (an aldose) to C-2 of D-fructose (a

• The differences of sucrose from other dissaccharides are :

1. There are 2 anomeric carbon that used for glycoside linkage.

2. Glucose and fructose in sucrose have no hemiacetal group, because sucrose isn’t an equilibrium state with forms aldehyde or keton in water .

3. Sucrose have no mutarotation and isn’t reducing sugar.

OH

OH

H

H

OHH

OH

H2OH

CH2OHH

CH2OH

OH H

H OH

O

O

ALPHA-GLUKOPIRANOSE

BETA-FRUKTOFURANOSE

Poly saccharide • Repeated condensation of 1,4 -D-glucose

• Polyglucose

• Contains 1000 to 2000 glucose units

• It has α 1,4 glycoside linkage

1. Amylose

• It has flexibility to form conformation

Coil / helix

O

O

O

o

o

O O

O

HO

O O

O

Amylose

2. Amylopectin. • A polymer of α -D- glucose

• It isn’t entirely a straight-chain molecule, but has random branches with α 1,6 glycoside linkage

• There are 20 – 25 glucose units in the straigth chain form with α 1,4 glycoside linkages

• Test with Iodine ( I2 ) gives deep

purple colour.

• A Macromolecule contains 105

to 106 glucose units

O

OH

OH

CH2OHO

OH

OH

CH2OH

O

OH

OH

CH2

O

OH

OH

CH2OH

O

OO

O O

On

n

Amylopectin

Glycogen ( also called animal starch)

Glycogen is similar to amylopectin, has α 1,6 glycosidic linkage at branching points and α 1,4 glycosidic libjkage at the straigth-chain portions.

The structural difference between glycogen and amylopectin is in the degree of branching. There are 10 to 12 glucose units at straight chain.

It is a “giant molecule”, containing about 106 glucose units.

Cellulose.

• A linear polymer containing D-glucose units, all in the 1,4 glycosidic linkage

• The structural difference between cellulose and amylose : in cellulose all the 1,4 glycosidic linkages are β.

• Cellulose is the most abundant molecule in living tissues.

O

OH

OH

CH2OHO OH

OH

OH

CH2OH

O

OH

OH

CH2OHO

O

OH n Cellulose

Acidic Polysaccharides

•The tissues are matrix between organs and cells that provides:

• The important role : in the structure and function of connective tissue

• mechanical strength

• filters the flow of molecular information between cells.

Specialized form

Examples :

Cartilage, bone, synovial fluid, skin, tendons, blood vessel walls, intervertebral disks and cornea.

Hyaluronic acid.

• A typical and the simplest (structurally) acidic polysaccharide of connective tissue

• A “ giant molecul “ : molecular weigth 105 – 107, contains from 300 to 100 000 repeating units, depending the organ in which it occur.

• Most abundant in embryonic tissue and in specialized connective tissues such as :

- The synovial fluid : acts as lubricant

- The vitreous of the eye : its function is to provide a clear, elastic gel that maintains the retina in its proper position.

Molecular structure of hyaluronic acid :

Composed of D – glucuronic acid linked to N – acetyl glucosamine by β 1,3 linkage, the latter in turn is linked to

the next glucuronic acid by β 1,4 linkage.

O

NH

CH2OHO

OH

OH

CH2OH

O

OH

OH

CH2OH

O

O

O

CCH3

O

OH

O nGlucoronic acid

Glucoronic acid

N-Acetylglucosamine

Hyaluronic acid

Heparin. • It is one of the most acidic polysaccharides, ocuurs in such tissues as lung, liver, skin and intestinal mucosa

• Biological function : anticoagulant activity prevents blood clotting.

O

OSO3-

OH

C

OO

O

NHSO3H

OH

CH2OSO3H

O

OO-

HEPARIN

O

OSO3-

OHCOO-

NH

OSO3-

CH2OSO3-

O

C O

CH3

O

n

THANK YOU !!!