过氧化氢修饰（钠，钾）-ATP酶后动力学协同性的变化

Kinetic cooperativity change after H2O2 modification of (Na,K)-ATPase.

作者信息

Garner M H, Garner W H, Spector A

出版信息

J Biol Chem. 1984 Jun 25;259(12):7712-8.

Abstract

The kinetics of hydrolysis of ATP and p-nitrophenylphosphate and the action of the allosteric effectors, Na+ and K+, upon the hydrolysis of these substrates were used to study the H2O2-modified, uncoupled (Na,K)-ATPase isolated from cultured bovine lenses ( Garner , W. H., Garner , M. H., and Spector , A. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 2044-2048). Pure bovine renal (Na,K)-ATPase was modified by H2O2 in 150 mM KCl and 20 mM MgCl2 to yield an enzyme with kinetic properties similar to the enzyme isolated from the H2O2-treated, cultured bovine lens. H2O2 modification changes the interaction of the ATP hydrolysis site from negative to positive kinetic cooperativity. H2O2 modification dramatically alters Na+ stimulation of ATP hydrolysis and Na+ inhibition of p-nitrophenylphosphate hydrolysis while having little effect upon K+ control of the hydrolysis of these two substrates.

摘要

利用ATP和对硝基苯磷酸酯的水解动力学以及变构效应物Na⁺和K⁺对这些底物水解的作用，来研究从培养的牛晶状体中分离出的经H₂O₂修饰的、解偶联的（Na，K）-ATP酶（加纳，W.H.，加纳，M.H.，和斯佩克特，A.（1983年）美国国家科学院院刊80，2044 - 2048）。在150 mM KCl和20 mM MgCl₂中，纯牛肾（Na，K）-ATP酶被H₂O₂修饰，产生一种酶，其动力学性质类似于从经H₂O₂处理的培养牛晶状体中分离出的酶。H₂O₂修饰将ATP水解位点的相互作用从负动力学协同性转变为正动力学协同性。H₂O₂修饰显著改变了Na⁺对ATP水解的刺激作用以及Na⁺对对硝基苯磷酸酯水解的抑制作用，而对这两种底物水解的K⁺调控影响很小。