COVALENT FLAVIN COENZYME IN FLAVOENZYME CATALYSIS

单胺氧化酶A和B位于细胞外膜， 线粒体膜 每种酶都含有一个8 α-S- 半胱氨酰FAD辅酶和催化氧化脱氨 生物胺，如血清素和多巴胺， 神经递质，也在肾钠调节中起作用 重吸收 该项目旨在了解 详细的催化机理，特别是C-H模式 键断裂，并使用结构-功能研究来阐明 对于它们各自的底物特异性重要的因素 催化位点 使用一种新的酵母表达系统， 人肝酶，核黄素类似物的影响 结构上; a）共价结合酶的黄素和B） 将研究辅酶在催化中的作用。 包括停流动力学研究在内的机制方法， 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三个 在文献中提出的催化机制，以及测试 MAO A和MAO B是否通过类似的催化作用起作用 机制等 这些研究的结果应该提供新的 深入了解这两个活性位点的结构， 避免输入酶，这可能导致 开发可用于以下的改进的特异性抑制剂： 诸如抑郁症的疾病的临床治疗， 增强帕金森病患者的左旋多巴治疗。

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.