聚合度3～6甲壳寡糖的制备与TOF-MS分析

Preparation and Analysis of Chitosan Oligomers of Polymerization Grade 3 to 6

本文用自制酸性蛋白酶粗酶液降解壳聚糖,研究了降解过程中温度、pH值、反应时间、酶用量及壳聚糖脱乙酰度(DD)对酶降解能力的影响。以85.5%脱乙酰度(DD)、分子量(Mw)为56.0×104的壳聚糖为底物,45℃、pH4.6降解数小时,降解产物由红外光谱、分子量测定(GPC)和基体辅助激光解吸电离飞行时间质谱(MALDI TOF MS)表征。主要降解产物的脱乙酰度有所降低;酶解8h,其水解产物用NaOH调至pH9无沉淀,9h分子量降为0.93×103,经MALDI TOF MS分析产物为聚合度3～6的甲壳寡糖,3～6糖中各糖含量分别为13.3%、27.3%、49.0%、10.1%。

Partially N-acetylated chitosan was degraded by a homemade and efficient acidic proteinase. The effects of reaction temperature,pH,time,enzyme concentration and DD of chitosan on the hydrolysis of chitosan were investigated. The degradation was monitored by the concentration of reducing sugar and GPC. Then chitosan of 85.5% degree of deacetylation was depolymerized at 45℃ and pH 4.6 for a few hours. The degraded chitosans were characterized by FT-IR,GPC and MALDI-TOF-MS. The data revealed that the deacetylation degree of the hydrolyzates was reduced. After 8h, the hydrolyzate was neutralized to pH 9 and no precipitation was found. After 9h,the degree of polymerization of the product were mainly from 3 to 6 . The percents of them were 13.3%,27.3%,49.0% and 10.1%, respectively.