通过酶促反应制备壳寡糖

用酶降解法对壳聚糖进行降解 ,研究了温度、pH值、金属离子等对酶促反应的影响 ,降解的最佳温度和pH值分别为 5 0℃和 5 0 ,Mg2 + 和Ca2 + 对酶降解具有一定的促进作用 ,而重金属离子Cu2 + ,Ni2 + 和Zn2 + 对酶降解有强烈的抑制作用。通过降解过程中壳聚糖溶液粘度的变化可以得出 ,该壳聚糖酶是以内切方式作用于壳聚糖。采用离子交换色谱柱对降解产物进行分离 ,得到了聚合度为 2～ 9的壳寡聚糖。该酶促反应符合米氏动力学方程 ,米氏常数Km 值为 2 60 1g/L ,Vmax 值为 3 5 79× 10 - 2 g/min·L。

Preparation of Chitooligosaccharides by Enzymatic Hydrolysis

Chitosan was hydrolyzed by enzymatic method, and the effects of temperature, pH value, metal ions and concentration of substrate on chitosan hydrolysis were studied The optimal temperature and pH for hydrolysis were 50℃ and 5 0 respectively Metal ions of Mg 2+ and Ca 2+ could speed the hydrolysis reaction, but heavy metal ions of Cu 2+ , Ni 2+ and Zn 2+ inhibited the reaction strongly The chitosanase functioned an endo splitting manner from the rapid decrease of the viscosity of chitosan solution Chitooligosaccharides with DP 2～9 were obtained by ion exchange chromatography of hydrolysis product Kinetic parameters K m is 2 601?g/L, V max  is 3 579×10 -2 ?g/min·L