解淀粉芽胞杆菌α-淀粉酶(Bacillus amyloliquefaciens α-amylase,BAA)是淀粉加工、织物退浆、食品等相关工业中最主要的中温型淀粉液化酶,但其工业应用属性一直未被深入研究。该研究基于酶分子进化原理,获得了催化属性显著改善的BAA突变体E2M6。与BAA相比,突变体E2M6的最适作用温度提高5 ℃,最适作用pH则未发生变化,突变体酶活性对Ca2+、Mg2+、Na+等金属离子的依赖性显著降低,其淀粉水解效率(κcat/Km)较BAA提高了1.75倍,显示其具有更好的工业应用价值。
Bacillus amyloliquefaciens α-amylase (BAA) is one of the most important α-amylase preparations used in starch processing,textile desizing and food industries.However,its industrial properties are not well studied and improved.Using artificial evolution method,a mutant (E2M6) of BAA was obtained.Compared to wild-type BAA,its temperature optimum was increased by 5 ℃ and the pH optimum was not significantly changed.Its activity depended on Ca2+,Mg2+ and Na+ was significantly reduced.The starch-hydrolyzing efficiency (κcat/Km) was increased by 1.75 times.The results indicated that the BAA mutant developed in this study is of potential application in starch processing.
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