大肠杆菌无机焦磷酸酶中的效应位点在三聚体间界面发生突变时得以揭示。

Effectory site in Escherichia coli inorganic pyrophosphatase is revealed upon mutation at the intertrimeric interface.

作者信息

Sitnik Tatyana S, Vainonen Julia P, Rodina Elena V, Nazarova Tatyana I, Kurilova Svetlana A, Vorobyeva Natalya N, Avaeva Svetlana M

机构信息

Chemistry Department, Moscow State University, Leninskie Gory, 119992 GSP-2, Moscow, Russia.

出版信息

IUBMB Life. 2003 Jan;55(1):37-41. doi: 10.1080/1521654031000072139.

DOI:10.1080/1521654031000072139

PMID:12716061

Abstract

Escherichia coli inorganic pyrophosphatase (E-PPase) is a homohexamer formed from two trimers related by a two-fold axis. The residue Asp26 participates in intertrimeric contacts. Kinetics of MgPPi hydrolysis by a mutant Asp26Ala E-PPase is found to not obey Michaelis-Menten equation but can be described within the scheme of activation of hydrolysis by a free PPi binding at an effectory subsite. Existence of such a subsite is confirmed by the finding that the free form of methylenediphosphonate activates MgPPi hydrolysis though its magnesium complex is a competitive inhibitor. The Asp26Ala variant is the first example of hexameric E-PPase demonstrated to have an activatory subsite.

摘要

大肠杆菌无机焦磷酸酶（E-PPase）是一种同型六聚体，由通过二重轴相关的两个三聚体形成。残基Asp26参与三聚体间的相互作用。发现突变体Asp26Ala E-PPase催化MgPPi水解的动力学不遵循米氏方程，但可以在游离PPi结合到效应子亚位点激活水解的机制内进行描述。亚甲基二膦酸的游离形式可激活MgPPi水解，尽管其镁络合物是竞争性抑制剂，这一发现证实了这种亚位点的存在。Asp26Ala变体是已证明具有激活亚位点的六聚体E-PPase的首个实例。