盘基网柄菌中依赖NAD的谷氨酸脱氢酶的动力学特性及激活机制

Kinetic properties and the mechanism of activation of NAD-dependent glutamate dehydrogenase from Dictyostelium discoideum.

作者信息

Pamula F, Wheldrake J F

机构信息

Faculty of Science and Engineering, School of Biological Sciences, Flinders University of South Australia, Adelaide, Australia.

出版信息

Biochem Mol Biol Int. 1996 Apr;38(4):729-38.

PMID:8728102

Abstract

Two forms of the NAD-dependent glutamate dehydrogenase were partially purified from Dictyostelium discoideum, an activated and a non-activated form. V(max) for the non-activated enzyme was stimulated 88-fold and the activated enzyme 3-fold by 0.1 mM AMP (at their pH optima). Half maximal stimulation by AMP is achieved at 221 +/- 39 microM for the non-activated enzyme and 20 +/- 2 microM for the activated enzyme. We have shown that activation of NAD-GDH in vivo has many similarities to trypsin treatment of non-activated enzyme and that proteolysis is the probable mechanism of activation.

摘要

从盘基网柄菌中部分纯化出了两种依赖NAD的谷氨酸脱氢酶形式，一种是活化形式，一种是非活化形式。在其最适pH值下，0.1 mM AMP可使非活化酶的V(max)提高88倍，活化酶的V(max)提高3倍。非活化酶在221±39 μM的AMP浓度下达到最大刺激的一半，活化酶在20±2 μM的AMP浓度下达到最大刺激的一半。我们已经表明，体内NAD-GDH的活化与用胰蛋白酶处理非活化酶有许多相似之处，并且蛋白水解可能是活化的机制。