Partial acid hydrolysis glycosidic bonds

Chitin is insoluble in water and barely soluble in acidic media (forming ammonium salts). Heating in acid or alkahne solutions leads to the hydrolysis of bound N-acetyl-n-glucosamine with the formation of n-glucosamine and acetic acid. Heating under acidic conditions causes partial depolymerisation of chitin through the hydrolysis of P-glycosidic bonds. In alkaline solutions, depolymerisation occurs to a lesser extent. 

Treatment of mushroom cultures with sodium [l- C]acetate and sodium [2- C]acetate yielded the two differently labell glycosides (28b). Acidic hydrolysis of the glycoside resulted in partial double bond migration, and two alygcones, (28a) and (30), were isolated. 

The structure elucidation of BLM was not straightforward because of the noncrystalline nature of the molecule [36]. An extensive degradation study indicated that BLM contains novel amino acid constituents and an unusual disaccharide, i.e., pyrimidoblamic acid (1), rytfcro-P-hydroxy-L-histidine (2), (2S, 35,4/ )-4-amino-3-hydroxy-2-methylpentanoic acid (3), 2 -(2-aminoethyl)-2,4 -bithiazole-4-carboxylic acid (4), and 2-0-(3-0-carbamoyl-a-D-mannopyranosyl)-a-L- u/opyranose (5) (Fig. 9). The sequence of the peptide bonding and the glycoside linkage was established by selective partial hydrolysis and, in 1978, the total structure was eventually determined by Takita et al. on the basis of further direct and indirect evidence (Fig. 1) [2]. 

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