氯过氧化物酶的化学修饰及其在溶液中结构与催化性能的关系

摘要

Chloroperoxidase（CPO） was modified by TMA and PMDA.Compared to native CPO,the chlorinated activity increased by 54% and 34% respectiviely,the thermostability and the tolerance of organic solvents also were enhanced;Enzyme protein molecules structure in solution was studied by UV-vis spectroscopy,fluorescence and circular dichroism（CD）.The results show that heme in the modified CPO is more exposed for easy access of substrate and alpha helix in the modified CPO is enhanced resulting in improvement of the enzyme protein deactivation ability.Enzyme kinetics analysis shows that the decrese of Km and the increase of kcat/Km proved that an increase of the affinity and selectivity of CPO to substrate,this is the main reason why the modified enzymes activity can be increased.%选用1,2,4-苯三甲酸酐（TMA）、均苯四甲酸酐（PMDA）对氯过氧化物酶（CPO）进行化学修饰,与天然酶相比,修饰酶T-CPO和P-CPO的催化活性分别提高了54%和34%,同时对温度及有机溶剂的抗失活能力都有所提高.酶蛋白分子溶液结构的紫外-可见光谱（UV-vis）、荧光光谱以及圆二色谱（CD）等光谱分析表明,CPO的血红素辅基暴露程度增加,底物容易接近活性中心,同时CPO的α-螺旋结构得以加强,从而有效提升了酶蛋白的抗失活能力.酶促反应动力学研究表明,米氏常数Km的减小以及kcat/Km的增大说明CPO对底物的亲和力及识别的专一性得以改善,这是修饰酶活性提高的主要原因.