Derivatized Monosaccharides

ways which monosacchrides are modified

1. phosphate addition

2. deoxy sugars

3. amino sugards

4. sugar alcohols

5. sugar acids

phosphate addition is

used in metabolic pathways

hemiacteal phosphates are

more reactive than alchohol phosphates

deozy sugars have

oh groups replaced by H

amino sugars

NH2 group subs for oh (usually at c2)

sugar alcohols

reduction of carbonyl to an alcholhol

sugar acids

oxidation of carbonyl to an acid

Rb

ribose

Xylose

XYL

Pentoses

Rb, Xyl

Hexoses

Fru, Gal, Glc, Man

Fru

Fructose

Galactose

Gal

Man

Mannose

Glucose

Glc

Deoxy sugars

Fuc

Fuc

Fucose

Amino sugars

GlcN, GaIN, GlcNAc, GaINAc, NeuNAc, MurNAc,

N-Acetylmuramic acid

MurNAc

N-Acetylneuraminic acid

NeuNAc

N-Acetylgalactosamine

GalNAc

N-Acetylglucosamine

GlcNAc

GalN

Galactosamine

GlcN

Glucosamine

if the anomeric carbon is free it can undergo

further oxidation to an acid; anomerica carbon reduces

A sugar is nonreducing if

there are covalent bonds at all anomeric carbons

the anomeric carbon is

reactive and there are a number of compouns that contain sugars joined through a glycosidic bond

the anomeric carbon will be involved in

covalent bonds between sugars in di, oligo, and polysaccharides

Since the sugar is oxidized the other

group in the reaction is reduced

A ring with an unreacted anomeric carbon is still in eq with the open form and can be

reduced

glycosidic bond

primary strurual linkage of all monosaccharide polymers

disaccharide

covalent linkage between anomerica carbon and several possible hydroxyls of a second monosaccharide

Anomeric carbon

C1 of hexoses and pentoses adjacent to the ring oxygen and possessing a hydroxyl

The anomeric carbon can react with a hydroxyl group in a

dehydration reaction

A glycosidic bond is designated by

1. alpha or b configuration of anomeric carbon

2. Number of carbons in the glycosidic bond

lactose is an

important disaccharide found in milk

sucrose is a

disaccharide naturally occuring in many plants and cyanobacteria

two anomeric c atoms bonded creates a

non-reducing disaccharide

Reducing sugar –

monosaccharides and disaccharides with a free, reactive carbonyl group or anomeric carbon

Non-reducing sugar

disaccharides with both anomeric carbons involved in glycosidic bond formation.