Glucosamine moieties

Hyaluronic Acid by Group A Streptococcus. III. Origin of iV-Acetyl-glucosamine Moiety. J. biol. Chemistry 212, 583 (1955)-... 

This enzyme, reportedly catalyzing the hydrolysis of terminal, nonreducing iV-acetyl-)3-glucosamine moieties in chitobiose and higher analogs, is now a deleted EC entry [EC 3.2.1.30]. 

The answer is d. (Hardman, pp 1242-1243.) Streptozocin is an alkylating agent with the capacity to cross-link DNA, thereby inhibiting its synthesis. It is a nitrosourea-like antibiotic that contains a glucosamine moiety that allows it to be selectively taken up by the p cells of the islets of Langerhans. Consequently, it can be useful in treating metastatic islet cell carcinoma. 

The N-acetyl-D-glucosamine moiety in both chitins can be considered as the magnetic independent residue in full agreement with the crystal structure of a- and p-chitin where this residue is also the crystallographic independent unit. Table 2.12 shows the similarity in a- and p-chitin NMR signals which means that solid-state NMR is not the appropriate technique to differentiate them. 

FIGURE 16.25 Modification of the acyl group of the glucosamine moiety of sLe. ... 

The terms aminoglycoside as well as aminocyclitol antibiotic which are used for this class of natural products refer to the structural aspect. Most of the aminoglycoside antibiotics contain aminosugars and an aminocyclitol or a cyclitol moiety. The middle furanose part in streptomycin is called streptose and was the first branched-chain sugar obtained from microorganisms. The other rings in streptomycin are a IV-methyl-L-glucosamine moiety and an aminocyclitol called streptidine (O Fig. 20). 

Since myeloperoxidase (MPO), the enzyme that generates HOCl under in vivo conditions, is known to play a very important role in inflammation, the reaction between HOCl and HA has been studied very comprehensively. In the repeating unit of HA, the glucosamine moiety represents the most relevant site of reactivity while the glucuronic acid moiety is quite inert against the action of HOCl [248]. 

Scheme 3.2. 1,2-and 1,5-H-shift in amidyl radicals of glucosamine moietie... 

The O-SP of S. (fysenteriae type 1 consists of approximately 25 copies of the tetrasaccharide repeating unit 1, which contains a-linked L-rhamnose, D-galactose, and D-7V-acetyl-glucosamine moieties ( ). 

From this result, it was confirmed that 3-amino-5-hydroxybenzoic acid was the direct biosynthetic precursor of the w-CyN unit of porfiromycin. Because of its chemical structure, it might be thought that tryptophan could be involved in the biosynthesis of the mitomycins, like those alkaloids possessing an indole nucleus, whereas in fact the mitomycins were biosynthesized from an m-CyN unit and a D-glucosamine moiety. 

Hitose-Kumagai A, Yagiia A. Akamatsu N. tlDP-N-mcthyl-D-glucosamine-phosphatc. A possible intermediate of N-methyl-L-glucosamine moiety of str omycin. J Antibiot 1982 35 1571-1577. 

The attack of hydroxyl radicals on o-glucuronate or iV-acetyl-D-glucosamine moieties of HA can also lead to the opening of rings without breaking the polymer chain [15, 16]. 

C.H. Ng, S. Hein, K. Ogawa, S. Chandrkrachang, and W.E Stevens, Distribution of D-glucosamine moieties in heterogeneously deacetylated cuttlefish chitin, Carbohydr. Polym., 69,382-390, 2007. 

Similar studies were carried out using uniformly labeled glucose (456). The results paralleled those obtained using the labeled acetate. The AT-acetyl and glucosamine moieties of hyaluronic acid metabolized at the same rate. The components of chondroitin sulfate appeared to be converted into the polysaccharide at the same rate but at a rate slower than that for hyaluronic acid. 

The sequence of reactions by which the amino sugar is incorporated into polysaccharides is not clear. It is not known whether a phosphorylated compound is essential to this synthesis. Hexokinase does not appear to phosphorylate JV-acetylglucosamine. In studies on the biosynthesis of hyaluronic acid by Streptococcus hemolyticus, glucose-l-C was added to the medium. Glucosamine was isolated from the synthesized polysaccharide, and the major fraction of the radioactivity of the compound was present in Ci. This experiment suggests that the glucosamine moiety of hyaluronic acid arises from glucose. ... 

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