Kinetics of the exchange reaction catalyzed by 2-amino-3- ketobutyrate CoA ligase

作     者：Farrukh Jamil 

作者机构：School of Biological Sciences University of the Punjab New Campus Lahore 54590 Punjab Pakistan Department of Biosciences COMSATS Institute of Information Technology(CIIT) Sahiwal 57000 Punjab Pakistan 

出 版 物：《Frontiers in Biology》 (生物学前沿（英文版）)

年 卷 期：2015年第10卷第6期

页      面：503-507页

核心收录：

学科分类：0710[理学-生物学] 0831[工学-生物医学工程（可授工学、理学、医学学位）] 090403[农学-农药学(可授农学、理学学位）] 0830[工学-环境科学与工程（可授工学、理学、农学学位）] 081702[工学-化学工艺] 1001[医学-基础医学(可授医学、理学学位)] 08[工学] 0817[工学-化学工程与技术] 09[农学] 0904[农学-植物保护] 0836[工学-生物工程] 0713[理学-生态学] 

基　　金：Higher Education Commission  Pakistan  HEC 

主　　题：enzyme 2-amino-3-ketobutyrate CoA ligase kinetics exchange reaction 

摘      要：2-Amino-3-ketobutyrate CoA ligase （KBL） of Escherichia coli is a member of the a-oxoamine synthase family; it catalyzes the condensation reaction between glycine and acetyl CoA to yield 2-amino-3-ketobutyrate. We have previously shown that KBL catalyzes the exchange ofpro-R hydrogen of glycine with protons in the medium; however, the kinetics of this reaction has never been determined. In this study, we calculated the kinetic parameters of this exchange reaction by using different concentrations of [2RS- 3H2： 2-14C] glycine. The rate of the exchange reaction was determined by measuring the 3H/14C ratio in recovered ｜2S- 3H： 2J4C]glycine. The Lineweaver-Burk plot showed that Km and kcat of this reaction were 3.8 ×10^-3 M and 0.22 S^-11, respectively. On the other hand, Km and kcat values of the overall KBL-mediated catalysis were correspondingly 1.23 × 10^-2 M and 1.19 S^-1. Thus, the rate of the exchange reaction was almost five times lower than that of overall KBL catalysis.