Hemmings B A
J Biol Chem. 1978 Aug 10;253(15):5255-8.
The NAD-dependent glutamate dehydrogenase from Candida utilis was isolated from 32P-labeled cells following enzyme inactivation promoted by glutamate starvation and found to exist in a phosphorylated form. Analysis of purified, fully active NAD-dependent glutamate dehydrogenase (a form) and inactive NAD-dependent glutamate dehydrogenase (b form) for alkalilabile phosphate revealed that the a form contained 0.09 +/- 0.06 mol of phosphate/mol of enzyme subunit and b form 1.25 +/- 0.06 mol of phosphate/mol of enzyme subunit. Phosphorylation caused a 10-fold reduction in enzyme specific activity. Dephosphorylation (release of 32P) and enzyme reactivation occurred on incubation with cell-free yeast extracts, indicating the presence of a phosphoprotein phosphatase in such preparations.
产朊假丝酵母的NAD依赖型谷氨酸脱氢酶在谷氨酸饥饿诱导酶失活后，从经32P标记的细胞中分离得到，发现其以磷酸化形式存在。对纯化的、具有完全活性的NAD依赖型谷氨酸脱氢酶（a型）和无活性的NAD依赖型谷氨酸脱氢酶（b型）进行碱不稳定磷酸盐分析，结果显示a型每摩尔酶亚基含0.09±0.06摩尔磷酸盐，b型每摩尔酶亚基含1.25±0.06摩尔磷酸盐。磷酸化使酶的比活性降低了10倍。与无细胞酵母提取物一起温育时发生去磷酸化（32P释放）和酶再活化，表明此类制剂中存在一种磷蛋白磷酸酶。
