COVALENT FLAVIN COENZYME IN FLAVOENZYME CATALYSIS

单胺氧化酶A和B定位于胞外 线粒体膜。每种酶都含有一个8α-S- 半胱氨基FAD辅酶催化氧化脱氨基 生物胺，如5-羟色胺和多巴胺，其功能是 神经递质及其在肾钠调节中的作用 重吸收。本项目旨在实现对 其详细的催化机理，特别是C-H模式 键断裂，并用结构-功能研究来阐明 底物特性中的重要因素 催化点。利用一种新的酵母表达系统表达 核黄素类似物对人体肝酶的影响 结构；a)与酶结合的共价黄素和b) 辅酶在催化中的作用将被研究。 包括停流动力学研究在内的机械方法， 动力学同位素效应的研究，以及磁场对 动力学性质将被用来区分这三个 文献中提出的催化机理以及测试 MAO A和MAO B是否通过类似的催化作用发挥作用 机械装置。这些研究的结果应该会提供新的 对这两个活性中心结构的洞察 从药理上进口的酶可能会导致 改进的特异性抑制剂的开发可能有助于 抑郁症和TO等疾病的临床治疗 加强L多巴治疗帕金森病的疗效。

Monoamine oxidases A and B are localized in the outer mitochondrial membrane. Each enzyme contains an 8 alpha-S- cysteinyl FAD coenzyme and catlyzes the oxidative deamination of biogenic amines such as serotonin and dopamine which function as neurotransmitters and also functio in regulation of renal sodium reabsorption. This project seeks to achieve an understanding of their detailed catalytic mechanisms; particularly the mode of C-H bond cleavage and to use structure-functon studies to elucidate the factors important in substrate specificities for their respective catalytic sites. Using a novel yeast expression system for the human liver enzymes, the influence of riboflavin analougue structure on; a) the covalent flavin binding to the enzymes and b) the function of the coenzyme in catalysis will be investigated. Mechanistic approaches including stopped flow kinetic studies, kinetic isotope effect studies, and the influence of magnetic field on the kinetic properties will be employed to distinguish among three proposed catalytic mechanisms in the literature as well as to test whether MAO A and MAO B function via similar catalytic mechanisms. The results from these studies should provide new insights into the structures of the active sites of these two pharmacologically import enzymes which may lead to the development of improved specific inhibitors which may be useful in the clinical treatment of disorders such as depression and to potentiate L-DOPA therapy of patients with Parkinson's Disease.