Structure, Regulation and Mechanism of the Action of Oxidizing Enzyme

拟议的项目是直接延续和扩大 在NSF项目下进行的研究 利用这次调查的发现 的一个方面 该项目的中心是神经毒性胺MPTP（N- 甲基-4-苯基-1，2，3，6-四氢吡啶）及其 通过两种形式的单胺氧化酶（MAO）的结构类似物， 已知存在于哺乳动物线粒体中， 吡啶氧化对单胺氧化酶A和B的可逆抑制作用 MPTP类似物的产物。 这些叔胺具有深刻的 生物化学家、药理学家和神经生物学家的兴趣 因为在人类、灵长类动物和其他物种中 它们诱发的神经系统疾病 在帕金森病人身上看到的。 神经毒素的表达 作用是由这些化合物的4-电子氧化引发的。 四氢吡啶通过一种或两种形式的脑MAO。 一 研究了MAO A和MAO B的结构要求， 这些叔胺的氧化完全揭示了 这些酶的特异性的意想不到的方面， 已经产生了关于其催化作用的重要新信息， 特性. 更多种类的结构类似物仍然存在， 用这些不同的酶形式进行测试。 的另一方面 该计划进一步探索了神经元死亡的机制， 由MAO形成的吡啶鎓化合物引起。 已知 它们通过阻断线粒体的呼吸， 辅酶对黄素蛋白NADH脱氢酶的再氧化 Q. m在此拟议计划下的结构-功能研究 应该大大增加我们对以下要求的理解： MPP+类似物与NADH脱氢酶的相互作用。 我们计划 扩展我们最近的实验，这些实验证明， 经典的NADH脱氢酶抑制剂（鱼藤酮，杀粉蝶菌素， 和巴比妥酸盐）在同一位点结合并与MPP+竞争， 其类似物。 将这些研究扩展到光亲和类似物 MPP+和同源物的含量预计将确定 复合物NADH脱氢酶分子的亚基接近 到Q减少点。

The proposed project is a direct continuation and expansion of studies conducted under NSF project exploiting findings in that investigation. One aspect of the project centers on the oxidation of the neurotoxic amine MPTP (N- methyl-4-phenyl-1,2,3,6- tetrahydropyridine) and of its structural analogs by the two forms of monoamine oxidase )MAO), which are known to exist in mammalian mitochondria, and the reversible inhibition of MAO A and B by the pyridinium oxidation products of MPTP analogs. These tertiary amines are of profound interest to biochemists, pharmacologists, and neurobiologists because in humans, subhuman primates, and certain other species they induce neurological conditions essentially identical with those seen in Parkinson patients. Expression of their neurotoxic action is initiated by the 4-electron oxidation of these tetrahydropyridines by either or both forms of brain MAO. A study of the structural requirements of MAO A and MAO B for rapid oxidation of these tertiary amines has revealed completely unexpected facets of the specificities of these enzymes and has already yielded major new information concerning their catalytic properties. Many more classes of structural analogs remain to be tested with these different enzyme forms. Another aspect of the program explores further the mechanism of neuronal death caused by the pyridinium compounds formed by MAO. It is known that they inhibit the respiration of mitochondria by blocking the reoxidation of the flavoprotein NADH dehydrogenase by Coenzyme Q. m Structure-function studies under this proposed program should greatly increase our understanding of the requirements for the interaction of MPP+ analogs with NADH dehydrogenase. We plan to expand our recent experiments which have demonstrated that the classical inhibitors of NADH dehydrogenase (rotenone, piericidin, and barbiturates) bind at the same site and compete with MPP+ and its analogs. Extension of these studies to photoaffinity analogs of MPP+ and congeners is expected to establish which of the subunits of the complex NADH dehydrogenase molecular are close to the Q reduction site.