Modification amino-sugars

A polysaccharide composed entirely of amino sugar residues is named by appropriate modification of the systematic amino sugar name. 

It is important to note that the foregoing, biosynthetic-polymer modification is usually incomplete. In fact, only a fraction of the heparin precursor undergoes all of the transformations shown in Scheme 1. However, as the product of each enzymic reaction constitutes the specific substrate for the succeeding enzyme, the biosynthesis of heparin is not a random process. Thus, sulfation occurs preferentially in those regions of the chain where the amino sugar residues have been N-deacetylated and N-sulfated, and where D-glucuronic has been epimerized to L-iduronic acid.20... 

The protection of amino groups of amino sugars benefits particularly from the use of new blocking groups introduced for peptide synthesis. In this context, light-sensitive urethans and amides that can be utilized for the protection of amino groups in amino sugars are of particular interest in saccharide synthesis and modification. 

J. Jurczak and A. Golfbiowski, The synthesis of antibiotic amino sugars from a-amino aide hydes, Antibiotics and Antiviral Compounds, Chemical Synthesis and Modification, (K. Krohn, H. Kirst, and H. Maas, eds.), VCH, Weinheim, 1993, p. 343. 

The titration data were analyzed by a computer program, which was a modification of the program SCOGS (17). The systems Ni(II) and L-serine or L-threonine, as analogs of amino-sugar acids, and boric acid and mannitol-borate were evaluated. For each of these systems it was convenient to refine first the formation constants for the simple complexes, such as ML and ML2, adding other more complex species later until the best fit to the data had been obtained. 

Acetamidodeoxyhexoses. A further modification of the 4-keto-inter-mediate has been independently shown by Ashwell and by Strominger and associates (Table I, References 20, 21, 22, 23). Transamination reactions with L-glutamate as the amino donor and pyridoxal phosphate as coenzyme led to formation of 3-amino 3,6-dideoxy- and 4-amino 4,6-dideoxyhexoses, respectively. Acetylation with acetyl coenzyme A yields the naturally-occurring N-acetyl amino sugar derivatives. 

Modification of this procedure was applied to the analysis of neutral and amino sugars in mucins [440]. A mixture of 0.2% of ethylene glycol succinate, 0.2% of ethylene glycol adipate and 1.4% of silicone XE-60 was used as the stationary phase and the analysis was effected with temperature programming at l°C/min from 150 to 205°C. Similar results could be obtained, however, on a column packed with 3% of OV-225. Partially ethylated alditol acetates were used to determine the components of polysaccharides [441],... 

Whiton, R. S., Lau, P., Morgan, S. L., Gilbart, J., and Fox, A. (1985). Modifications in the alditol acetate method for analysis of muramic acid and other neutral and amino sugars by capillary gas chromatography-mass spectrometry with selected ion monitoring. /. Chromatogr. A 347, 109—120. 

---