Biochemistry Classification Of Carbohydrates

Carbohydrates are polyhydroxylated compounds having at least 3 carbon atoms and a potentially active carbonyl group which may be an aldehyde or a keto group.

Polyhydroxyl aldehyde or ketone

Aldoses

Eg; aldotriose aldohexose

Ketose Eg; ketotriose ketohexose

Monosaccharides; one unit of carbohydrate

Disaccharides; two units of Carbohydrates

Oligosaccharides; two to ten monosaccharide units

Polysaccharides; hundreds of monosaccharide units

Isomers are molecules that have the same molecular formula, but have a different arrangement of the atoms in space. E.g. fructose, glucose, mannose, and galactose are isomers of each other having formula C6H12O6.

EPIMERS are sugars that differ in configuration at ONLY 1 POSITION. Examples of epimers : D-glucose and D-galactose (epimeric at C4) D-glucose and D-mannose (epimeric at C2)

ENANTIOMERS: A special type of isomerism found in pairs of structures that are mirror images of each other. The mirror images are termed as enantiomers and the two members are designated as D- and L- sugar. The vast majority of sugars in humans are D-sugars. In D form the OH group on the asymmetric carbon is on the right. In L form the OH group is on the left side.

A carbon linked to four different atoms or groups farthest from the carbonyl carbon.

It involves the reaction of C-5 OH group with the C-1 aldehyde group or C-2 of keto group. Six membered ring structures are called Pyranoses while five membered ring structures are called Furanoses.

The carbonyl carbon after cyclization becomes the anomeric carbon.This creates α and β configuration.In α configuration the OH is on the same of the ring in fischer projection. In Haworths it is on the trans side of CH2OH.

The spontaneous interconversion of α and β anomers in solution.

Sugars in which a hydroxyl group (common on carbon 2) is replaced by an amino group e.g. D-glucosamine and D-galactosamine.

Monosaccharides in which an -H has replaced an – OH group

(formed from D-mannose by reduction reactions). It is found among carbohydrate components of glycoproteins, such as those of the ABO blood group determinates on the surface of red blood cells

The pentose sugar component of DNA.

Mucopolysaccharides are protective polysaccharides. They are attached to proteins. They are gel like substances known to fill the space of most tissues

connective tissue

Skin

bone

cartilage body cells

mucous secretions

synovial fluids

Proteoglycans are glycosaminoglycans covalently linked to serine residues of specific core proteins. Protein (5%) + polysaccharide (95%)

Mucopolysaccharidosis are a group of metabolic disorders caused by the absence or malfunctioning of lysosomal enzymes needed to break down molecules called glycosaminoglycans.

1. Serious physical disorders

2. Various genetic deformities including skeletal deformities (especially of the face), mental retardation and decreased life expectancy.

Hepatomegaly

Splenomegaly

Enlarged tongue

Retinal pigmentation

Hip dislocation

Heart murmurs

Heart valve damage from thickening

Glycosylation is the process or result of addition of saccharides to proteins and lipids.

The process plays an important role in the synthesis of membrane and secreted proteins.

Majority of proteins synthesized in the rough ER undergo glycosylation.

It is an enzyme -directed site-specific process.

Glycosylation may play a role in cell-cell adhesion (a mechanism employed by cells of the immune system), as well.

Two types of glycosylation exist: N-linked glycosylation to the amide nitrogen of asparagine side chains and O-linked glycosylation to the hydroxy oxygen of serine and threonine side chains.

glycoproteins have structural functions: constituent of the cell wall; form connective tissues such as collagen; found in gastrointestinal mucus secretions; used as protective agents and lubricants ;found abundantly in the blood plasma.

The human blood groups A, B, AB, and O depend on the oligosaccharide part of the glycoprotein on the surface of erythrocyte cells. The terminal monosaccharide of the glycoprotein at the nonreducing end determines blood group.

Oligosaccharides are antigenic determinants . Carbohydrates on cell surfaces are immunochemical markers. ABO blood group antigens are oligosaccharide components of glycoproteins and glycolipids on the surfaces of individual cells, besides blood cells.

an anti-A antibody- A antigen reaction.

clumps together (agglutinates) the transfused erythrocytes, resulting in an often fatal blockage of blood vessels