Mechanisms of Enzymatic Reactions

酶促反应机制

• 批准号: 6765992
• 负责人: PERRY A. FREY
• 金额: $ 36.38万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 1978
• 资助国家: 美国
• 起止时间: 1978-04-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6765992
• 关键词: Escherichia coli; UTP hexose 1 phosphate uridylyltransferase; X ray crystallography; active sites; ammonia lyase; bioenergetics; carbohydrate metabolism; catalyst; chemical kinetics; enzyme mechanism; enzyme structure; enzyme substrate complex; galactokinase; galactose; hydro lyase; isomerase; mass spectrometry; nicotinamide adenine dinucleotide; nuclear magnetic resonance spectroscopy; ornithine; proline; site directed mutagenesis; stereochemistry; tumor suppressor proteins; uridine

DESCRIPTION (provided by applicant): The long term objective is to elucidate the mechanisms by which binding energy facilitates enzymatic catalysis. A global approach will be adopted in studies of four enzymes that participate in carbohydrate and amino acid metabolism and phosphotransfer, UDP-galactose 4-epimerase (epimerase-NAD+), dTDP-glucose 4,6-dehydratase (dehydratase-NAD), ornithine cyclase (cyclase-NAD+), and human Fhit, a putative tumor suppressor. Chemical, kinetic, spectroscopic, mutagenic, and crystallographic methods will be employed. Carbohydrate metabolism is essential in all living cells and presents fundamental questions bearing on binding energy and catalysis. Cells must break down carbohydrates as energy sources and must produce specific carbohydrates, such as galactose for glycoconjugates. One manifestation of the importance of galactose metabolism is the metabolic defect underlying galactosemia, in which galactose metabolism is impaired by defects in enzymes. The objective in studies of epimerase will be to elucidate the molecular basis for the enhancement of the chemical reactivity of the niacin-coenzyme NAD+ by the use of binding energy between substrates and the enzyme. The structural basis for a charge-transfer interaction between NAD+ and the enzyme will be determined. Research on dehydratase-NAD+ will contrast its biological mechanism with that of epimerase-NAD+. The objectives for cyclase-NAD+ research include the elucidation of the chemical mechanism in the cyclization of ornithine into proline. Research on Fhit is directed toward elucidating its chemical reaction mechanism and the chemical basis for its activity as a tumor suppressor and its mechanistic relationships with galactose-1-P uridylyltransferase.

描述（由申请人提供）：长期目标是阐明结合能促进酶催化的机制。 将采用全局方法研究参与碳水化合物和氨基酸代谢和磷酸转移的四种酶：UDP-半乳糖4-差向异构酶（差向异构酶-NAD+）、dTDP-葡萄糖4,6-脱水酶（脱水酶-NAD）、鸟氨酸环化酶（环化酶-NAD+）和人 Fhit（一种假定的肿瘤抑制因子）。 将采用化学、动力学、光谱、诱变和晶体学方法。碳水化合物代谢对于所有活细胞至关重要，并提出了与结合能和催化有关的基本问题。细胞必须分解碳水化合物作为能量来源，并且必须产生特定的碳水化合物，例如用于糖复合物的半乳糖。半乳糖代谢重要性的表现之一是半乳糖血症的代谢缺陷，其中半乳糖代谢因酶缺陷而受损。差向异构酶研究的目的是阐明通过利用底物与酶之间的结合能来增强烟酸辅酶 NAD+ 化学反应性的分子基础。 NAD+ 和酶之间电荷转移相互作用的结构基础将被确定。 对脱水酶-NAD+的研究将其生物学机制与差向异构酶-NAD+的生物学机制进行对比。 环化酶-NAD+ 研究的目标包括阐明鸟氨酸环化为脯氨酸的化学机制。 对Fhit的研究旨在阐明其化学反应机制、其抑癌活性的化学基础及其与半乳糖-1-P尿苷酰转移酶的机制关系。