PAR对氨基酰化酶不可逆抑制动力学研究

A KINETIC STUDY ON IRREVERSIBLE INACTIVITION OF AMINOACYLASE BY PAR

本文将邹氏的在酶的活性修饰剂存在下的底物反应动力学理论应用于氨基酰化酶被金属螯合剂PAR脱锌而失活的动力学研究。通过对不同浓度的PAR存在下底物反应过程和含有PAR的不同浓度的底物中酶促反应的分析,讨论了PAR对氨基酰化酶的脱锌机制。这一过程很可能按如下机制进行:首先,PAR与酶分子活性部位的锌结合,形成一复合物,这一步是较快的反应,然后发生一个可逆的构象变化,最后是不可逆的去锌步骤。锌的存在显然稳定了酶活性部位的构象,而这正是酶活性所必需的。

The kinetic theory of the sulstrate reaction during modification of enzyme activity previously described by Tsou, C.-L. has been used to study the kinetics of the course of removal of Zn2 + from aminoacylase leading to inactivation of enzyme by PAR. The kinetics of the substrate reaction under different concentrations of the substrate chloroacetyl-L-alanine and the inactivator PAR suggest a complex mechanism for inadivation by PAR and substrate competition with PAR at the active site.The initial formation of an enzyme-Zn-PAR complex is a relatively rapid reaction followed by a slow inactivation step which involves probably- a change in conformation of the enzyme.The presence of Zn2+ stabilizes the active site conformation required for enzyme activity.