Polysaccharides, acetolysis hydrolysis

Formolysis and acetolysis are not common methods for cleavage of glycosidic linkages. They do have some unique applications, however. For instance, methylated polysaccharides are not generally soluble in hot water, and consequently, hydrolysis is best preceded by formolysis under these circumstances. For example, 5 mg of methylated polysaccharide is dissolved in 3 mL of 90% formic acid, and the solution is kept for 2 h at 100°. The formic acid is removed by evaporation at 40°. The residue is dissolved in 1 mL of 250 mM sulfuric acid and the solution is heated for 12 h at 100°, cooled, the acid neutralized with barium carbonate, the... 

Various techniques have been utilized for sequencing the glycosyl residues of polysaccharides and oligosaccharides. These techniques are elaborations of the commonplace procedure of converting polysaccharides, by partial hydrolysis, into structurally analyzable oligosaccharides. This conversion is generally achieved by partial hydrolysis with acid, by acetolysis,131 or by formolysis.62 These reagents may differ in the... 

The insoluble polysaccharide was characterized by examination of the soluble, " G-labeled oligosaccharides isolated by a variety of treatments, including enzymic hydrolysis, partial hydrolysis with acid, or acetolysis. From the polymer containing D-mannose- C, several oligosaccharides were isolated having various ratios of D-mannose to D-glucose, from 1 1 to 3 or 4 1. One of these oligosaccharides was a disaccharide tentatively identified as an 0-/3-D-man-... 

Crab, shrimp, and lobster shells, waste products of the sea food industry, are the best sources of the polysaccharide. Calcium carbonate is first removed by hydrochloric acid and then protein and other organic impurities by extraction with sodium or potassium hydroxide solutions. Complete acid hydrolysis of chitin, although requiring drastic conditions, yields almost theoretical amounts of D-glucosamine and acetic acid (Chapter VIII), whereas controlled acid or enzyme hydrolysis produces V-acetyl-D-glucosa-mine. Acetolysis of chitin or acetylation of the partial acid hydrolysis products gives among other products chitobiose octaacetate which has been... 

Linear Pentasaccharides. - Several glucopentaoses have been reported. The a-l,2-linked compound which is a pentamer fragment of polysaccharide II of Mycobacterium tuberculosis, has been synthesized, and the p-l,3-Iinked isomer has been obtained by acetolysis, followed by hydrolysis, of curdlan and converted to the dodecyl glycoside which was then partially sulfated to give a product showing some anti-HIV activity.Chemo-enzymic methods have been used in... 

Acetolysis provides a useful variation on the hydrolysis procedure it involves the fragmentation of the polysaccharide in mixed acetic and sulfuric acids at low temperatures, to produce oligosaccharide acetates directly. 

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