Hexosamines, acetylation

The Hexose, Hexosamine, Acetyl and Amide-Nitrogen Content of Hen s Egg Albumin, Biochem. J. 77, 239-247 (1960). 

Acetyl hexosamines N-Acetylglucosamine (GIcNAc) N-Acetylgalactosamine (GalNAc)... 

Both positional linkages (uronic acid to hexosamine and hexosamine to uronic acid) were established as being (1 — 4) by structural analysis of the previously mentioned (see Section IV), crystalline disaccharides containing D-glucuronic acid, isolated from an acid hydrolyzate of carboxyl-reduced heparin.128-129 Further evidence was obtained from the structure of the D-glucuronic acid-containing counterpart of disaccharides 6 and 8, obtained as minor products from pig-mucosal heparin following nitrous acid deamination,1110 136-138 and acid hydrolysis followed by N-acetylation,130 respectively. 

The amino sugar counterparts of D-glucuronic acid and nonsulfated L-iduronic acid in heparin are either N-acetylated, or nonsulfated at C-6, or both. 2-Acetamido-2-deoxy-D-glucosyl residues account for only a minor proportion of the total hexosamine in heparin, and are especially low in beef-lung preparations (see Table II).8,138,147 -149 In contrast, they... 

In penicillinbehandelten Staphylokokken wurde, an Uridindiphos-phat glykosidisch gebunden, eine MoRGAN-ELSON-positive Saure ge-funden, bei der es sich moglicherweise um eine JV-Acetyl-hexosamin-uronsaure handelt (206). 

Eine positive MoRGAN-ELSON-Reaktion (vgl. S. 826) kohlenhydrat-haltiger Naturstoffe gait bisher vielfach als Beweis fur die Anwesenheit reduzierender iV-Acetyl-hexosamin-Reste eine negative Probe bei vor-handenem Acetaminozucker wurde als Hinweis darauf erachtet, daB das Hexosamin glykosidisch verknupft sei. 

Sulfuric acid N-acetyl-hexosamine hexuronie acid... 

Type IV Pneumococcus Specific Polysaccharide.—This capsular material110 ([ck]d + 33°, water) has been hydrolyzed and shown to contain units of D-glucose and N-acetyl-hexosamine. Its structure has not yet been studied. 

The partially methylated monosaccharides obtained on depolymerization of the permethylated sample are preferably analyzed as acetates by g.l.c.-m.s., as shown by Bjomdal and coworkers.41,42 The neutral sugars and the amino sugars obtained in acetolysis-acid hydrolysis are reduced, and acetylated for the analysis, and the amino-hexitol and the neuraminic acid residues are acetylated after methanolysis. Identification with the aid of g.l.c.-m.s. has been described for all of the common components of protein- and lipid-linked glycans and oligosaccharides from animal cells, namely, the neutral sugars,41-43 hexitols,44 hexosamines,29,43,45,46 aminohexitols,31,32 and neuraminic acids.33,34,47... 

Aryl glycosides of 2-amino-2-deoxy sugars, as might be expected, can be prepared by similar techniques as was illustrated by the synthesis of phenyl 3,4,6-tri-0-acetyl-2-acetamido-2-deoxy-p-D-glucoside and -D-galactoside by toluene -sulphonic acid catalysed reactions between phenol and the hexosamine penta-acetates These products were then anomerised using zinc chloride as catalyst to provide means of obtaining -anomers. 

This enzyme [EC 3.2.1.52] (also known as /3-A-acetylhex-osaminidase, )3-hexosaminidase, hexosaminidase, and N-acetyl-/3-glucosaminidase) catalyzes the hydrolysis of terminal nonreducing A-acetyl-o-hexosamine residues in... 

The intravenous injection of 2-amino-2-deoxy-D-glucose-14C into rats, and subsequent isolation of the uridine diphosphate N-acetyl-hexosamine fraction, has been suggested as a fast and convenient method for preparing small amounts of a mixture of radioactive uridine 5 -(2-acetamido-2-deoxy-a-D-gIucopyranosyl pyrophosphate) and uridine 5 -(2-acetamido-2-deoxy-a-D-galactopyranosyl pyrophosphate). 

Chitin and chitosan derivatives have also been studied as blood compatible materials both in vivo and in vitro [520], Anticoagulant activity was greatest with O sulfated N acetyl chitosan, followed by N,0 sulfated chitosan, heparin, and finally sulfated N acetyl chitosan. The lipolytic activity was greatest for N,0 sulfated chitosan followed by heparin. The generally poor performance of chitosan was attributed to polyelectrolyte complexes with free amino groups present on the membrane surface. The O sulfate or acidic group at the 6 position in the hexosamine moiety was identified as the main active site for anticoagulant activity. 

The per-O-acetylated 1-chlorides of hexosamines can be prepared by treating the hexosamine with an excess of acetyl chloride at elevated temperature.97 Under these conditions, acetylation of the hexosamine occurs at all positions except C-l, at which a chlorine atom... 

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