芽孢杆菌WS-3L淀粉酶的纯化和特性的研究

Purification and Properties of the α-amylase from a Bacillus sp. WS-3L

摘要:

芽孢杆菌WS-3L产生的a-淀粉酶AmyL经过多步纯化, 酶的回收率为15.5%, 比活提高了345倍。该淀粉酶能够有效水解淀粉生成麦芽寡糖。酶的最适反应温度为45℃, 最适反应pH为6.5, 在pH 7.0~8.0, 40℃以下酶活较稳定; 离子Cu2+、NH4+、Ag+、Hg+ 和EDTA、SDS对酶活力有显著抑制作用, 而其他一些常见金属离子如Na+、K+则对酶活影响不大。AmyL对可溶性淀粉、直链淀粉、支链淀粉的Km值和Vmax分别为2.81 mg/mL、8.37 mg/mL、1.80 mg/mL和11.67 mmol/（min·mL）、10.00mmol/（min·mL）、13.33 mmol/（min·mL）, 表明支链淀粉是该酶的理想水解底物。玉米淀粉对AmyL有很高的吸附率, 预示这可以作为酶快速固定的一个简易方法应用到实际生产中。

关键词:芽孢杆菌, 淀粉酶, 水解, 性质

Abstract:

An extracellular α-amylase (AmyL) from a Bacillus sp WS-3L was purified 345 fold and had a recovery of 15.5%. The amylase was capable of hydrolyzing starch to yield a series of maltooligosaccharides. It was optimally active at 45℃ and pH values around 6.5 and showed stability at the temperature below 40℃ and pH 7.0-8.0. The amylase was inhibited by Cu2+、NH4+、Ag+、Hg+ and EDTA、SDS. Michaelist constants (Km) of the AmyL for were 2.81 mg/mL、8.37 mg/mL、1.80 mg/mL, and maximum velocity (Vmax) of the enzyme for soluble starch, amylose, amylopectin were 11.67μmol/(min·mL)、10.00μmol/(min·mL)、13.33μmol/(min·mL) respectively. It was suggested that amylopectin is the better hydrolysis substrate for the enzyme. It was observed that the adsorption and digestion of the enzyme on different raw starches was remarkably different. Raw corn starch exhibited high adsorption of the enzyme. It was suggested that the highly stable enzyme was able to be obtained and applied very fast by corn starch chromatography.

Key words:Bacillus, Amylase, Hydrolysis, Properties