MOLECULAR PROPERTIES OF PEP CARBOXYLASE REVELANT TO ITS ALLOSTERIC REGULATION

磷酸烯醇式丙酮酸（PEP）羧化酶是感兴趣的，因为它的中心酶是磷酸烯醇式丙酮酸。 在CAM和C4植物的光合代谢中的作用。 如将 作为主要代谢途径中的关键酶， 酶是高度调节的，一个基本的调节元件似乎 是由磷酸化激活剂引起的激活的相互作用， 葡萄糖6-磷酸和AMP的抑制作用以及苹果酸和ATP的抑制作用。 这项研究的总体目标是阐明各种分子方面 效应物，特别是激活剂如AMP和 葡萄糖6-磷酸，调节来自Crassula argentea的PEP羧化酶， 其他来源 这项研究将探测激活剂的结合位点 和抑制剂。 拟议 研究还将测试激活的分子机制，根据 一个最近被提出的新假设 具体目标 包括估计激活剂结合位点的数量， 活化剂的解离常数，确定是否所有 激活剂共享一个共同的结合位点，比较AMP和ATP结合 位点，鉴定激活剂结合位点处的肽序列，和 测试活化剂去磷酸化在活化过程中的作用。 这些结果有望提供分子信息， 活化剂对酶产生影响。 这些信息将 提供了更深入的了解这一结构-功能关系， 特定的酶，更一般地说，进入代谢过程， 酶水平的调节。

Phosphoenolpyruvate (PEP) carboxylase is of interest because of its central role in the photosynthetic metabolism of CAM and C4 plants. As would be expected for a key enzyme in a major metabolic pathway, the activity of the enzyme is highly regulated, and a fundamental regulatory element appears to be the interplay of the activation caused by phosphorylated activators such as glucose 6-phosphate and AMP and the inhibition caused by malate and ATP. The overall goal of this research is to elucidate various molecular aspects of the process by which effectors, particularly activators such as AMP and glucose 6-phosphate, regulate PEP carboxylase from Crassula argentea and other sources. The research will probe the binding site(s) of activators and inhibitors through the use of photoaffinity labels. The proposed research will also test the molecular mechanism of activation, in light of a novel hypothesis that has recently been proposed. The specific aims include estimating the number of activator binding sites and the dissociation constants for the activators, determining whether all activators share a common binding site, comparing the AMP and ATP binding sites, identifying the peptide sequence at the activator binding site, and testing the role of activator dephosphorylation in the activation process. The results are expected to provide molecular information on how and where activators exert their influence on the enzyme. This information will provide greater insight into the structure-function relationships of this specific enzyme and, more generally, into the process of metabolic regulation at the enzyme level.