Human Glucokinase

描述（由申请人提供）：葡萄糖激酶是人体内葡萄糖稳态的关键调节剂。葡萄糖激酶的调节和/或活性的功能障碍引起多种疾病，包括青年成熟型糖尿病（MODY）和婴儿高胰岛素血症（HI）。人葡萄糖激酶是一种受其糖底物D-葡萄糖变构调节的单体酶。这种动力学协同性对于维持体内适当的葡萄糖血清水平至关重要。本研究的目的是阐明人葡萄糖激酶协同作用的机制基础。本文所述的实验联合收割机将用于人葡糖激酶活性的强大遗传选择系统与机械酶学相结合，以提供引起协同性的构象转变的动力学和分子描述。具体目标是：（1）确定高胰岛素血症相关glk突变的激活机制;（2）通过化学猝灭流技术研究未配体葡萄糖激酶的构象异质性;（3）研究二级结构“变构开关”在葡萄糖激酶协同性中的作用;（4）确定脯氨酰顺式/反式异构化是否是导致酶构象缓慢相互转换的原因。实现本申请中概述的目标有望影响未来糖尿病和高胰岛素血症的葡萄糖激酶靶向治疗药物的开发。公共卫生相关性：在过去五年中，人葡萄糖激酶已成为糖尿病的一个有吸引力的治疗靶点。已经鉴定了许多葡萄糖激酶的小分子活化剂，并且已经证明几种在动物模型中有效调节血糖水平。本申请中概述的目标的成功完成将提供关于体内葡萄糖激酶调节机制的关键新信息。这些信息有可能对未来设计糖尿病和高胰岛素血症的葡萄糖激酶靶向治疗药物产生重大影响。

DESCRIPTION (provided by applicant): Glucokinase is a key regulator of glucose homeostasis in the human body. Dysfunction in the regulation and/or activity of glucokinase causes a diverse range of diseases including maturity onset diabetes of the young (MODY) and hyperinsulinemia of infancy (HI). Human glucokinase is a monomeric enzyme that is allosterically regulated by its sugar substrate, D- glucose. This kinetic cooperativity is critical to maintaining proper glucose serum levels in vivo. The goal of this study is to elucidate the mechanistic basis for cooperativity in human glucokinase. The experiments described herein combine a powerful genetic selection system for human glucokinase activity with mechanistic enzymology to provide a kinetic and molecular description of the conformational transitions that give rise to cooperativity. The specific aims are: (1) To determine the mechanism of activation of hyperinsulinemia-linked glk mutations; (2) To investigate conformational heterogeneity in unliganded glucokinase via chemical quench-flow techniques; (3) To investigate the role of a secondary structural "allosteric switch" in glucokinase cooperativity; (4) To determine whether prolyl cis/trans isomerization is responsible for the slow interconversion of enzyme conformations. Achieving the objectives outlined in this application promises to impact the development of future glucokinase-targeted therapeutics for diabetes and hyperinsulinemia. PUBLIC HEALTH RELEVANCE: In the past five years, human glucokinase has emerged as an attractive therapeutic target for diabetes. Numerous small-molecule activators of glucokinase have been identified and several have been shown to be effective at modulating blood glucose levels in animal models. The successful completion of the aims outlined in this application will provide critical new information about the mechanisms of glucokinase regulation in vivo. This information has the potential to significantly impact future efforts to design glucokinase-targeted therapeutics for diabetes and hyperinsulinemia.