Proteoglycans, ABO Blood groups, Hemagglutinin and Neuraminidase

Proteoglycans

Carbohydrates make up a much higher percentage by weight (up to 95%) compared to glycoproteins

What do many glycosaminoglycans consist of

repeating disaccharide units of a derivative of an amino sugar (Glucosamine or Galactosamine)- at least one of the two sugars in the repeating unit has a negatively charged carboxylate or sulfate group

What are proteoglycans used for

connective tissue structure, lubrication, cell adhesion, and cell proliferation

Aggrecan

PROTEOGLYCAN: large proteoglycan protein essential for the structure and function of cartilage, as well as the central nervous system

Aggrecan Protein Component

2397 amino acids

Aggrecan Glycosaminoglycan Component

Chondroitin 6 Sulfate and Keratan Sulfate- water molecules bind with the charged groups of the glycosaminoglycans

What are aggrecans linked together by

hyaluronan (hyaluronic acid)

What determines blood group

specific carbohydrates (oligosaccharides) on the surface of red blood cells (A, B, or O)- they have the common foundation of the O-antigen

A-antigen

O-antigen + extra GalNAc (alpha-1,3 linkage)

B-antigen

O-antigen + extra Gal (alpha-1,3 linkage)

Glycosyltransferases

enzyme that has a specific variant for each oligosaccharide antigen- thus blood group of offspring are determined by which glycosyltransferases were inherited from the parents

Hemagglutinin

viral glycan-binding protein that binds to sialic acid (acid sugar) located at the ends of oligosaccharide chains present on cell-surface glycoproteins and glycolipids

Neuraminidase

viral enzyme that cleaves the oligosaccharide to release the virus

How do anti-flu pharmaceuticals work

inhibit neuraminidase