Effects of different valences of cerium ion on conformation of Horseradish Peroxidase

作     者：相丽 葛志强 

作者机构：Education Ministry Key Laboratory of Systems Bioengineering College of Chemical Engineering and Technology Tianjin University 

出 版 物：《Journal of Rare Earths》 (稀土学报（英文版）)

年 卷 期：2008年第26卷第6期

页      面：857-863页

核心收录：

学科分类：081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 070303[理学-有机化学] 0703[理学-化学] 

主　　题：cerium conformation horseradish peroxidase heme rare earths 

摘      要：Our previous studies demonstrated that Ce^4＋could induce reactive oxygen species （ROS） burst as a signal to promote pacilitaxel biosynthesis in suspension cultured Taxus cuspidate cells. To further understand the mechanism of cerium ions inducing ROS burst, circular dichroism （CD）, synchronous fluorescence, and electron paramagnetic resonance （EPR） were used to detect them inducing conformational change of horseradish peroxidase （HRP）. Horseradish peroxidase activity was reduced by 78% by 0.1 mmol/L Ce^4＋, whereas it was only reduced by 28% by 0.1 mmol/L Ce^3＋. Circular dichroism spectra showed that the percentage of transition from helical content and other structure to β strands and flturns was 23.1 when induced by Ce^4＋, whereas it was only 13.2 when induced by Ce^3＋. In synchronous fluorescence spectra, Ce^4＋ led to red shift and intensity-elevation of tryptophan fluorescence emission maximum, whereas in the case of Ce^3＋, the results were a contrast to the above. Furthermore, g factor （gx and gy） in electron paramagnetic resonance （EPR） induced by Ce^4＋ and Ce^3＋ was significantly different. These results indicated that the different valence of cerium ion induced various conformations of HRP, and Ce^4＋ was more effective than Ce^3＋. This suggested that Ce^4＋ affected the burst of ROS through changing the conformation of oxidoreductase.