壳聚糖的酶法降解

Enzymatic Degradation of Chitosan

用壳聚糖酶降解壳聚糖,探讨了壳聚糖降解过程中温度、pH值、底物浓度和金属离子对酶促反应的影响。结果表明:酶促反应进行到5 h左右时,即可得到聚合度小于10的壳寡糖。该酶促反应的最适温度为50℃,最适pH=5.5;最适底物浓度为0.02 g/mL;金属离子Ca2+和Mg2+对酶降解有一定的促进作用,而Zn2+、Cu2+对酶降解有较强的抑制作用。该酶促反应符合米氏动力学方程,米氏常数Km=7.80 g/L,最大反应速率Vmax=7.72 g/(min.L)。

The enzymatic degradation of chitosan was performed in a bioreactor by the chitoanase from aspergillus niger, and the effects of temperatrue, pH, chitosan concentration and metal ions were investigated. Chitooligosaccharides with average polymerization degree less than 10 were obtained after the chitosan was degradated by the chitoanase for 5 h. The optimal temperatrue, pH, substrate concentration of the degradation reation are 50℃, 5.5 and 0.02 g/mL, respectively. It was found that ions Ca^2＋ and Mg^2＋ stimulated the chitoanase activity significantly, while Zn^2＋ and Cu^2＋ had inhibitory effects. The enzymatic degradation reaction is in accord with the Michaelis-Menton Equation, and the kinetic parameters Km= 7.80g/L, Vmax= 7.72g/（min. L）.