Galactosamine acetylation

Figure 13-10. Glucosamine (2-amino-D-glucopyra-nose) a form). Galactosamine is 2-amino-D-galactopy-ranose. Both glucosamine and galactosamine occur as N-acetyl derivatives in more complex carbohydrates, eg, glycoproteins.

The ABO blood group substances in the red cell membrane are complex glycosphingohpids the immunodominant sugar of A substance is A -acetyl-galactosamine, whereas that of the B substance is galactose. 

Dermatan sulfate, also termed chondroitin sulfate B, a related glycosaminoglycan constituent of connective tissue, was known to be composed of galactosamine and a uronic acid, originally believed to be glucuronic acid but then claimed to be iduronic acid based largely on color reactions and paper chromatography. However, the d or L-enantiomer status of the latter monosaccharide was not clear. Jeanloz and Stoffyn unequivocally characterized the monosaccharide as L-iduronic acid by consecutive desulfation, reduction, and hydrolysis of the polysaccharide, followed by isolation of the crystalline 2,3,4-tri-0-acetyl-l,6-anhydro-/ -L-idopyranose, which was shown to be identical to an authentic specimen synthesized from 1,2-0-isopropylidene-/ -L-idofuranose.34... 

Selective Oxidation of Terminal B-D-Galactose (or N-acetyl-galactosamine) Groups... 

Figure 2.10 Structure of two sample oligosaccharide side chains (one N-linked the other O-linked) found in glycoproteins. Man manose Gal galactose SA sailic acid GlcNAc W-acetyl glucosamine GalNAc W-acetyl galactosamine...

PHA Red kidney bean A-Acetyl-D-galactosamine IV-Acetyl-D-galactosamine... 

ELB Elderberry bark Sialic acid or A-acetyl-D-galactosamine Lactose... 

Morquio A MPS IVA AT-acetyl-galactosamine 6-sulfatase Keratan sulfate... 

Maroteaux-Lamy MPS VI AT-acetyl-galactosamine-4-sulfatase Dermatan sulfate... 

Chondroitin sulfates (CS) are ubiquitous components of extracellular matrices of all connective tissues such as the artery and tendon and exhibit a variety of biological functions. They are linear copolymers made up of dimeric units composed of glucuronic acid and N-acetyl galactosamine. The first biological investigation... 

Nitroglycals65 are excellent Michael-type acceptors,66 where O-, N-, S-, C- and P-nucleophiles can be used as donors.67 An application of this kind of reaction was reported by Schmidt et al. for a new synthesis of 2-deoxy-2-nitro-D-galactose nucleoside 86 and of /V-acetyl-D-galactosamine nucleoside 88, based on addition reactions to 3,4,6-tri-0-benzyl-2-nitro-D-galactal 85 (Scheme 28).68... 

Figure 12.15 Gangliosides. The prefix mono-, di, tri- or tetra- denotes the number of sialic acid W-acetyl neuraminic acid, NANA) residues present in the molecule. The many different gangliosides have complex structures and for convenience shorthand notations are used. The two commonest were introduced by Svennerholm, who named the parent compound GM1, and Wiegnandt, who named it Ggnti. The latter system gives enough information for the structures to be worked out from the shorthand form once the symbols have been learnt. GalNAc represents N-acetyl galactosamine in the above structure.

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