STUDIES ON CHITOSAN .4. LYSOZYMIC HYDROLYSIS OF PARTIALLY N-ACETYLATED CHITOSANS
STUDIES ON CHITOSAN .4. LYSOZYMIC HYDROLYSIS OF PARTIALLY N-ACETYLATED CHITOSANS
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DOI：
10.1016/s0141-8130(05)80032-7
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发表时间：
1992-08-01
影响因子：
8.2
通讯作者：
AIBA, S
中科院分区：
文献类型：
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作者：
AIBA, S
通过测定部分N-乙酰化壳聚糖的还原糖及其水解物的相对分子质量，研究了部分N-乙酰化壳聚糖的溶酶消化率。由甲壳素在非均相条件下N-脱乙酰化得到的中等N-脱乙酰化壳聚糖(MDC)的早期可消化性是均相条件下高度N-脱乙酰化壳聚糖(PAC-H)的4倍左右。与PAC-H相反，MDC的水解物分子量迅速下降，但逐渐达到恒定值。30%N-乙酰化MDC的K(M)为0.14 mm，65%N-乙酰化PAC-H的K(M)为0.12 mm，但后者的N-乙酰化度是前者的两倍。这些差异是由于两种壳聚糖中N-乙酰基的分布方式不同所致。乙酰基含量为20~30%的MDC含有3个以上的N-乙酰-D-氨基葡萄糖残基，而乙酰基含量为30%左右的PAC-H为N-乙酰-D-氨基葡萄糖和D-氨基葡萄糖单元的无规共聚物。乙酰基含量大于50%的PAC-H具有三个以上N-乙酰-D-氨基葡萄糖残基的序列。
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 K(m) 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.