Ca^(2+)诱导的淀粉液化芽孢杆菌α-淀粉酶分子的生物活性和结构变化

Bioactive Change and Structural Change of Bacillus Amyloliquefaciens α-Amylases Induced by Ca^(2+)

在研究Ca2+对淀粉液化芽孢杆菌α-淀粉酶分子生物活性影响的基础上,采用荧光光谱法和傅里叶变换红外光谱法研究了Ca2+诱导的酶分子结构变化.结果表明,当溶液中Ca2+浓度低于25.0 mmol/L时,Ca2+对酶分子具有激活作用;而当Ca2+浓度高于25.0 mmol/L时,Ca2+对酶分子的生物活性具有抑制作用.在Ca2+诱导的淀粉液化芽孢杆菌α-淀粉酶分子结构变化过程中,酶分子仅发生二级结构的变化,并不涉及其三级结构.当Ca2+对酶分子具有激活作用时,酶分子中的无规卷曲结构及β-折叠结构的含量下降,而α-螺旋结构及β-转角结构的含量上升;而当Ca2+对酶分子生物活性具有抑制作用时,酶分子中的α-螺旋结构及β-转角结构的含量下降,而无规卷曲结构及β-折叠结构的含量上升.

Based on the effect of bivalent calcium ions(Ca2 +) on the biological activity of Bacillus amyloliquefaciens α-amylases,the structural change of Bacillus amyloliquefaciensα-amylases induced by Ca2 +was studied via fluorescence spectroscopy and Fourier-transformation infrared spectroscopy. The results showed that when the concentration of Ca2 +in solution was below 25 mmol / L,the enzyme molecules could be activated by Ca2 +in solution,when the concentration of Ca2 +was over 25 mmol / L,the biological activity of enzyme molecules could be inhibited by Ca2 +. In the structural change of Bacillus amyloliquefaciens α-amylases induced by Ca2 +,only their secondary structures rather than their tertiary structures were involved; and when Ca2 +showed an activation effect to the bioactivity of the enzyme molecules,the contents of disorder structures andβ-sheet structures in the enzyme molecules decreased,and the α-helix ones and the β-turn ones increased.Whereas when Ca2 +showed an inhibition effect to the bioactivity of the enzyme molecules,theα-helix structures and β-turn structures in the enzyme molecules decreased,and disorder ones and theβ-sheet ones in the enzyme molecules increased.