CSB327H1 Lecture Notes - Lecture 8: Tetrasaccharide, Vitreous Body, Umbilical Cord
16 Nov 2012
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Proteoglycan = core protein + link tetrasaccharide + gag. The point of attachment is a ser residue. The link tetrasaccharide is o-linked to ser. The gag is covalently (o-linked or n-linked) attached to the core protein via link tetrasaccharide, except ha: ha non-covalently attached to core protein. Proteoglycans act as organizers of the ecm and promoters of cell adhesion. There are four major classes of gags: ha = d-glucuronic acid + n-acetyl-d-glucosamine (non-covalently linked) Universal sequence in all organisms: cs = d-glucuronic acid + n-acetyl-d-galactosamine (o-linked) Can be sulfated to increase the negative charge: ds = l-iduronic acid + n-acetyl-d-galactosamine (o-linked) Epimerization of the cooh group on c5 to change the stereochemistry. Can be sulfated to increase the negative charge: hs = d-glucuronic acid or l-iduronic acid + n-acetyl-d-glucosamine or n-sulfo-glucosamine (o-linked) Binds the most counter ions: ks = d-galactose + n-acetyl-glucosamine (o-linked or n-linked) Can be sulfated to increase the negative charge.
