地衣芽胞杆菌α-淀粉酶(Bacillus licheniformis α-amylase,BLA)的耐热耐酸性特征,是其在淀粉酶法加工中最重要的应用属性。在通过人工进化获得BLA突变体V-2的基础上,该研究对其酶学性质进行了较全面的分析。突变体V-2在80℃和pH 5.5下表现出最高酶活力,最适作用温度和pH较BLA提高了10 ℃和降低了0.5~1.0个pH值,其耐热性和耐酸性显著优于BLA,该突变体的酶活力对金属离子特别是Ca2+的依赖性显著降低,该酶对淀粉水解作用明显优于BLA,其催化效率是BLA的33倍。
The heat- and acid-resistance of Bacillus licheniformis α-amylase (BLA) is the most important application property for enzymatic processing of starch. In this study, biochemical properties of mutant V-2 obtained by artificial evolution were comprehensively analyzed. V-2 showed the highest enzyme activity at 80℃ and pH 5.5, which was 10 ℃ higher and 0.5-1.0 pH lower than that of BLA, respectively. Its heat and acid resistance were significantly improved. The effects of metal ions, especially Ca2+, on the activity of V-2 were significantly reduced. V-2 was significantly more efficient than BLA in starch hydrolysis, with its catalytic efficiency 33 folds higher than that of BLA.
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