Mechanism of Cofactor Biogenesis in Copper Amine Oxidase

铜胺氧化酶（CAO）广泛存在于自然界中，催化原核生物和真核生物中伯胺的氧化脱氨。由于CAO活性增加与人类某些慢性疾病之间的相关性，该领域受到了极大的关注，并在过去十年中取得了许多令人兴奋的发现。也许，最重要的是三羟基苯丙氨酸醌（TPQ）作为CAO的氧化还原辅因子的鉴定。令人惊讶的是，发现共价辅因子来源于通过需要分子氧和二价铜离子的翻译后事件对活性位点酪氨酸的自催化修饰。多年来，积累了大量关于在催化过程中利用醌辅因子的机制的知识，并形成了将胺转化为相应醛的良好模型。然而，对CAO催化前体酪氨酸转化为活性成熟辅因子的策略缺乏充分的了解。为了解决有关活性位点铜的作用和蛋白质-蛋白质相互作用在这一过程中的贡献的基本问题，拟议研究的具体目标是（1）评价和鉴定潜在的化学中间体（2）评估铜的亲电性的作用和（3）确定亚基间通讯在TPQ生物发生机制中的作用。

Copper amine oxidases (CAO) are ubiquitously found in Nature and catalyze the oxidative deamination of primary amines in prokaryotes and eukaryotes. By virtue of the correlation between increased CAO activities and certain chronic diseases in man, much attention has been drawn to the field and has led to a number of exciting findings over the past decade. Perhaps, most important was the identification of trihydroxyphenylalanine quinone (TPQ) as the redox cofactor in CAO. Surprisingly, the covalent cofactor was found to be derived from the autocatalytic modification of an active site tyrosine by a post- translational event requiring molecular oxygen and a cupric ion. Over the years a wealth of knowledge apropos of the mechanism for the utilization of the quinocofactor during catalysis has accumulated and led to a well established model for the conversion of amines to their corresponding aldehydes. Nonetheless, a full understanding of the strategies employed by CAO to catalyze the transformation of the precursor tyrosine to the active mature cofactor is lacking. In an effort to address fundamental questions regarding roles of the active site copper and the contributions of protein-protein interactions in this process, the specific aims of proposed research are (1) to evaluate and identify a potential chemical intermediate (2) to assess the role of the electrophilicity of copper and (3) to ascertain the role of intersubunit communication in the mechanism for the biogenesis of TPQ.