地衣芽孢杆菌A.4041耐高温α-淀粉酶热稳定性及构象研究

Studies on the Thermostability and Conformation of Thermostable α-Amylase from Bacillus Licheniformis A.4041

近年来,对耐热酶特别是耐高温淀粉酶的研究十分活跃[1~3],地衣芽孢杆菌A.4041是我国自行诱变的耐高温α-淀粉酶的生产菌株[4].为了探索耐热酶的热稳定机理和规律,本文采用荧光光谱和圆二色谱法对地衣芽孢杆菌A.4041耐高温α-淀粉酶α-Ⅲ纯酶组...

The influence of heat on the conformation and stability of α amylase α Ⅲ fraction from Bacillus Licheniformis A.4041 was studied by means of the fluorescence and CD spectra. Heated at 80 ℃ for 15 min, the enzyme hardly lost its activity. At the same time, a considerable change of its fluorescence and CD spectra was observed. It was shown that, comparing with the whole conformation of the enzyme molecule, the active site has a relative stability. Heated at 90 ℃ for 15 min, the conformational and active changes resulted by Ca 2+ and starch were different. The Ca 2+ mainly affects the whole enzyme molecular conformations, whereas the substrate is important to sustain the activity. It indicates that the structure of enzymatic active site plays an important role to the thermostability of the α Ⅲ.