60周年校庆系列讲座－－7月24日Jean Chaudière教授：Mechanistic investigations of enzymes ……

　　主题：Mechanistic investigations of enzymes involved in the metabolism of polyphenols    
　　主讲人：Jean Chaudière教授
　　地点：生物楼二楼学术报告厅
　　时间：2013年7月24日（周三 ）14:00
　　主办单位：生环学院
　　联系电话：88320614
    
　　主讲人简介：
　　Jean Chaudière 博士，法国波尔多第一大学教授，毕业于加利福尼亚大学戴维斯分校，获博士学位。从事生物化学和酶学相关工作30多年。曾担任法国罗素-优克福(Roussel-UCLAF）实验室主管、Bioxytech公司CEO兼研究主管，到法国马恩河谷大学、巴黎第七大学访学。目前供职于波尔多第一大学，承担生物化学以及酶学的相关教学和科研工作，发表高水平论文数十篇。
    
　　讲座摘要：
　　This talk will focus on a few original techniques which we used in recent years to understand the complex behavior of polyphenolic substrates. Our studies of two NADPH-dependent reductases of the flavonoid pathway, namely dihydroflavonol reductase (DFR) and anthocyanidine reductase (ANR) will be first discussed. We will emphasize the use of deuterium labeling and tandem-mass spectrometry to shed light on the mechanisms of stereo- and regio-specificity of double-hydride transfers, and that of the chromatographic method of Hummel & Dreyer in equilibrium-binding studies. We will show that the unusually strong substrate inhibition observed with DFR and dihydroquercetin mostly results from the formation of a non-productive binary enzyme-polyphenol substrate in an ordered mechanism where NADPH is the first substrate, and that this could be rationalized in terms of head-to-tail binding of the polyphenolic structure when NADPH is not yet present at the active site. Finally, we will show how mass spectrometry can be used in real time to monitor a complex sequence of one-electron transfers and dimerization initiated by laccase on a tetracyclic polyphenol.