CHEMICAL MECHANISMS OF BIOSYNTHESIS

生物合成的化学机制

• 批准号: 3484240
• 负责人: RICHARD VANCE WOLFENDEN
• 金额: $ 23.18万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 1980
• 资助国家: 美国
• 起止时间: 1980-07-01 至 1995-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3484240
• 关键词: adenine phosphoribosyltransferase; adenosine deaminase; affinity chromatography; alpha galactosidase; alpha glucosidase; antimetabolites; chemical synthesis; dCMP deaminase; enzyme inhibitors; enzyme mechanism; enzyme substrate analog; enzyme substrate complex; hydrolase; inosine monophosphate; ligase; manganese; molecular rearrangement; nuclear magnetic resonance spectroscopy; purine /pyrimidine metabolism; purines; thymidine kinase

The theory of absolute reaction rates implies that the function of a catalyst depends on its affinity for activated intermediates in substrate transformation, in preference to the substrate in the ground state. These two forms of the substrate, which differ only slightly in structure, differ in binding affinity for an enzyme's active site by factors that equal or exceed the rate enhancement that an enzyme produces. Enzymes are extremely effective catalysts, enhancing rates of reaction of natural substrates by factors as large as 1017. Accordingly, if a stable compound could be made to resemble an activated intermediate in substrate transformation, then such an analog should be bound very much more tightly than the substrate itself. Through structural studies of enzyme complexes with transition state analogs and multisubstrate analogs, we are trying to gain a better understanding of the forces that re responsible for an enzyme's ability to discriminate between compounds that resemble each other so closely as the substrate in the ground state and the transition state. During the most recent project period, we have observed very high levels of structural discrimination between compounds that differ only in variations in ligand structure will be used, along with studies of enzyme-inhibitor complexes by exact physical methods, to analyze the extremely strong interactions that appear to be responsible for the binding by cytidine deaminase and adenosine deaminase of analogs of covalently hydrated intermediates in substrate transformation. We will explore the binding specificity and mechanism of action of glycosyl-transferring enzymes including beta- glucosidase, beta-galactosidase and nucleoside deoxyribosyltransferase, to gain a better understanding of the contributions of individual substituents to binding affinity. The binding properties of prolidase, a manganese- dependent peptidase that is extraordinarily sensitive to inhibition by polybasic acids including the natural product P-enolpyruvate, will be investigated. Other targets for inhibitor design will include several enzymes involved in the metabolism of purines: adenylosuccinate synthetase, IMP dehydrogenase and IMP cyclohydrolase.

绝对反应率的理论意味着A的功能 催化剂取决于其对底物激活中间体的亲和力 转化，优先于基材处于基态。 这些 两种形式的基板在结构上仅略有不同，不同 通过相等或 超过酶产生的速率提高。 酶极为 有效的催化剂，增强自然底物反应速率 相应地，如果可以制成稳定的化合物，则大于1017。 类似于底物转换中激活的中间体，然后 这样的模拟应该比基板更紧密地结合 本身。 通过与过渡的酶复合物的结构研究 状态类似物和多底层类似物，我们正在尝试获得更好的 理解负责酶的能力的力量 区分与彼此相似的化合物 基材处于基态和过渡状态。 在最多 最近的项目时期，我们观察到非常高的结构 歧视化合物仅在配体变化方面有所不同 将使用结构，以及对酶抑制剂复合物的研究 确切的物理方法，分析极强的相互作用 似乎负责胞苷脱氨酶的结合和 共价水合中间体类似物的腺苷脱氨酶 底物转换。 我们将探索具有约束力的特异性和 糖基转移酶的作用机制，包括β- 葡萄糖苷酶，β-半乳糖苷酶和核苷脱氧核糖基转移酶至 更好地了解单个取代基的贡献 具有绑定亲和力。 锰酶的结合特性，一种锰 依赖性肽酶对抑制非常敏感 包括天然产物p-烯醇丙酮酸在内的多质酸将是 调查。 抑制剂设计的其他目标将包括几个 参与嘌呤代谢的酶：腺苷核酸酯蛋白 合成酶，IMP脱氢酶和IMP环氢酶。