COFACTOR-DEPENDENT AMINE OXIDATIONS

胺生物氧化的机理多样性是一个主题。 目前的利益很大。经历了重大的代谢变化 所有脂肪胺都是N-脱烷基，尽管这个反应是 由不同的酶介导，取决于结构和程度 N-取代。细胞色素P-450与黄素依赖性 线粒体单胺氧化酶(MAO)被认为是氧化 伯胺/仲胺/叔胺 单电子转移，而铜胺氧化酶只氧化 苯醌辅助因子介导的伯胺转氨化反应 反应。拟议工作的目的是通过一项 结合酶学和模型研究，一些重要的 关于这些酶所使用的拟议机制的问题。在……里面 在某些情况下，对机构的理解被用来指导设计 和合成具有重要生理意义的选择性抑制剂 合作者正在研究酶。项目I涉及一个 脂肪胺对底物结构要求的研究 辣根过氧化物酶(HRP)和乳过氧化物酶，以努力 确认该机制是否涉及电子转移氧化。这个 反式-2-苯基环丙胺对HRP的灭活也将是 学习。项目二讨论的是 线粒体黄素依赖性单胺氧化酶(MAO) 建立热(与光化学相反)模型反应 在胺和“高潜力”黄素类似物之间，以及随后 阐明其作用机制。工作假说是， 机制实际上包括加法-消除或可能直接 氢原子/阴离子转移而不是初始单电子氧化 在氮气中。可能区分实际机制的新探测器 将会被调查。项目三侧重于初级教育的机制 2，4，5-三羟基苯丙氨酸介导的胺“转氨化” 哺乳动物铜胺氧化酶的(TOPA)苯醌辅因子，包括 已知的酶失活剂(环丙胺， β-氨基丙腈(BAPN)、1，2-二胺和 (氨甲基)三甲基硅烷)在模型苯醌反应体系中。新的 将合成赖氨酰氧化酶和二胺氧化酶的抑制剂，并 学习。与抑制剂BAPN有关，被认为是抑制 β-氰基丙氨酸对吡哆醛酶的作用，这一假说将是 在模型研究中进行了测试。

Mechanistic diversity in the biological oxidation of amines is a subject of much current interest. The major metabolic transformation undergone by all aliphatic amines is N-dealkylation, though this reaction is mediated by different enzymes, depending on structure and degree of N-substitution. Both cytochrome P-450 and the flavin-dependent mitochondrial monoamine oxidase (MAO) are thought to oxidize primary/secondary/tertiary amines via mechanisms which are initiated by single-electron transfer, whereas the copper amine oxidases oxidize only primary amines by way of a quinone-cofactor-mediated transamination reaction. The aim of the proposed work is to clarify, through a combination of enzymologic and model studies, a number of important questions concerning the proposed mechanisms used by these enzymes. In certain cases, understanding of the mechanism is used to guide the design and synthesis of selective inhibitors of physiologically important enzymes being studied by collaborators. Project I involves an investigation of the substrate-structure requirements of aliphatic amines for horseradish peroxidase (HRP) and lactoperoxidase, in an effort to confirm whether the mechanism involves electron-transfer oxidation. The inactivation of HRP by trans-2-phenylcyclopropylamine will also be studied. Project II addresses the mechanism of amine oxidation by the mitochondrial flavin-dependent monoamine oxidase (MAO), first through establishing a thermal (as opposed to photochemical) model reaction between amines and "high potential" flavin analogs, and subsequently elucidating the mechanism thereof. The working hypothesis is that the mechanism actually involves addition-elimination or possibly direct hydrogen atom/anion transfer rather than initial one-electron oxidation at nitrogen. New probes which might distinguish the actual mechanism will be investigated. Project III focuses on the mechanism of primary amine "transamination" mediated by the 2,4,5-trihydroxyphenylalanine (TOPA) quinone cofactor of the mammalian copper amine oxidases, including a study of the fate of known enzyme inactivators (cyclopropylamine, beta-aminopropionitrile (BAPN), 1,2-diamines, and (aminomethyl)trimethylsilane) in model quinone reaction systems. New inhibitors for lysyl oxidase and diamine oxidase will be synthesized and studied. Related to the inhibitor BAPN, is believed to be the inhibition of pyridoxal enzymes by beta-cyanoalanine, a hypothesis which will be tested in model studies.