Studies on chitosan: 4. Lysozymic hydrolysis of partially N-acetylated chitosans.
The lysozymic digestibility of partially N-acetylated chitosans was studied by measuring the reducing sugars produced and the molecular weights of their hydrolysates. Moderately N-deacetylated chitosans (MDC), obtained by N-deacetylation of chitin under heterogeneous conditions, were about four times more digestible at an early stage than partially N-acetylated chitosans (PAC-H) with similar acetyl content, prepared by N-acetylation of highly N-deacetylated chitosans under homogeneous conditions. The molecular weights of the hydrolysates of MDC decreased rapidly but gradually reached a constant value in contrast to the behaviour of PAC-H. The Km was 0.14 mM for 30% N-acetylated MDC and 0.12 mM for 65% N-acetylated PAC-H although the degree of N-acetylation of the latter was twice as much as the former. These differences were due to the different distribution patterns of N-acetyl groups in two types of the chitosans. MDC with 20-30% acetyl content have the sequences of more than three N-acetyl-D-glucosamine residues but PAC-H with about 30% acetyl content are random-type copolymers of N-acetyl-D-glucosamine and D-glucosamine units. PAC-H with more than 50% acetyl content have the sequences of more than three N-acetyl-D-glucosamine residues.
Aiba
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Biomimetic Chemistry Division, Industrial Products Research Institute, Ibaraki, Japan.
D000107:Acetylation; D002686:Chitin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D048271:Chitosan; D006868:Hydrolysis; D007700:Kinetics; D009113:Muramidase / Q000378:metabolism*
D002686:Chitin; D048271:Chitosan; D009113:Muramidase