大豆脂氧合酶对亚油酸作用的动力学分析

Kinetic analysis of the action of soybean lipoxygenase on linoleic acid.

作者信息

Lagocki J W, Emken E A, Law J H, Kézdy F J

出版信息

J Biol Chem. 1976 Oct 10;251(19):6001-6.

Abstract

The time course of the soybean lipoxygenase-catalyzed oxygenation of linoleic acid has been analyzed using a kinetic scheme based on two binding sites, compulsory product activation and competitive inhibition by substrate and by product. The dissociation constant (Kp) of the product from the free enzyme is much smaller than 10(-5) M, the dissociation constant of the substrate from the enzyme-substrate-product complex (Kps) has a value of (7.7 +/- 0.3) x 10(-6) M, and the competitive inhibitors constant of the product (Kpp) is equal to (2.9 +/- 0.3) x 10(-5) M Reduction of the hydroperoxide product to a hydroxy acid by sodium borohydride does not alter the product activation kinetics. From the study of the time course of the reaction, no evidence was found for the irreversible inactivation of the enzyme.

摘要

利用基于两个结合位点、强制产物激活以及底物和产物竞争性抑制的动力学方案，分析了大豆脂氧合酶催化亚油酸氧化的时间进程。产物从游离酶上的解离常数（Kp）远小于10^(-5) M，底物从酶 - 底物 - 产物复合物上的解离常数（Kps）值为(7.7 ± 0.3)×10^(-6) M，产物的竞争性抑制常数（Kpp）等于(2.9 ± 0.3)×10^(-5) M。硼氢化钠将氢过氧化物产物还原为羟基酸不会改变产物激活动力学。从反应时间进程的研究中，未发现酶不可逆失活的证据。