Burnell J N, Hatch M D
Arch Biochem Biophys. 1984 May 15;231(1):175-82. doi: 10.1016/0003-9861(84)90375-8.
These studies provide further information regarding the mechanism of the light/dark-mediated regulation of pyruvate,Pi dikinase in leaves. It is shown that a catalysis-linked phosphorylation of pyruvate,Pi dikinase can be demonstrated following incubation of the enzyme with [32P]phosphoenolpyruvate or [beta-32P]ATP plus Pi, that the enzyme-bound phosphate is located on a histidine residue, and that this phosphate is retained during ADP-mediated inactivation. Further evidence is provided that phosphorylation of this histidine is a prerequisite for ADP-mediated inactivation through phosphorylation of a threonine residue from the beta-phosphate of ADP. It is demonstrated that diethylpyrocarbonate (which forms a derivative with histidine residues) prevents [32P]phosphoenolpyruvate-dependent labeling (catalytic labeling) and [beta-32P]ADP-dependent labeling (inactivation labeling) of the enzyme. In addition, it is demonstrated that oxalate, an analog of pyruvate, competitively inhibits ADP-dependent inactivation with respect to ADP. The significance of these results is discussed with regard to the mechanism of regulation of pyruvate,Pi dikinase in vivo.
这些研究提供了关于叶片中光/暗介导的丙酮酸，磷酸二激酶调节机制的更多信息。结果表明，在用[32P]磷酸烯醇丙酮酸或[β-32P]ATP加磷酸孵育该酶后，可证明丙酮酸，磷酸二激酶存在催化相关的磷酸化作用，酶结合的磷酸盐位于组氨酸残基上，并且该磷酸盐在ADP介导的失活过程中得以保留。进一步的证据表明，该组氨酸的磷酸化是通过ADP的β-磷酸将苏氨酸残基磷酸化从而实现ADP介导失活的先决条件。已证明焦碳酸二乙酯（与组氨酸残基形成衍生物）可阻止该酶的[32P]磷酸烯醇丙酮酸依赖性标记（催化标记）和[β-32P]ADP依赖性标记（失活标记）。此外，已证明草酸盐（丙酮酸的类似物）相对于ADP竞争性抑制ADP依赖性失活。就体内丙酮酸，磷酸二激酶的调节机制对这些结果的意义进行了讨论。
