克雷伯杆菌甘油脱氢酶和1,3-丙二醇氧化还原酶的动力学机制

Kinetic mechanisms of glycerol dehydrogenase and 1,3-propanediol oxidoreductase from Klebsiella pneumoniae

摘要:

本研究主要对克雷伯杆菌甘油转化1,3-丙二醇代谢途径中的2个关键酶甘油脱氢酶 (GDH)、1,3-丙二醇氧化还原酶 (PDOR) 反应机制和动力学进行了研究。首先，通过初速度和产物抑制动力学研究确定了GDH、PDOR双底物酶促反应机制为有序BiBi机制，明确了由反应物消耗到产物生成之间的历程。其次，建立了GDH、PDOR双底物酶促反应动力学模型，由动力学模型可知，在偶合反应中，如果GDH和PDOR酶量相同，GDH氧化反应成为限速反应，而辅酶I将主要以氧化型NAD+形式存在。动力学信息为酶法合成1,3-丙二醇和代谢工程研究提供理论指导。

Abstract:

The kinetic mechanisms of two key enzymes in the biotransformation of glycerol to 1,3-propanediol (1,3-PD) by Klebsiella pneumoniae, glycerol dehydrogenase (GDH) and 1,3-propanediol oxidoreductase (PDOR), was characterized. Kinetics on initial velocity and product inhibition revealed that GDH and PDOR follow an ordered Bi-Bi sequential mechanism. Kinetic models for GDH and PDOR showed that the oxidation reaction catalyzed by GDH was the rate-limiting step in coupled enzymatic reaction when the GDH/PDOR was 1:1, and the NAD+ was the main form of coenzyme in the reaction. Knowledge about the kinetic mechanisms will be helpful to understand how these enzymes is regulated, which will be useful for further enzyme catalysis and metabolic engineering studies.