Mechanism of Cofactor Biogenesis in Copper Amine Oxidase

铜胺氧化酶（CAO）广泛存在于自然界中，在原核生物和真核生物中催化原胺的氧化脱胺反应。由于CAO活性增加与人类某些慢性疾病之间的相关性，在过去十年中，该领域受到了广泛关注，并产生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）作为氧化还原辅助因子的鉴定。令人惊讶的是，共价辅助因子被发现来自于一个活性位点酪氨酸的自催化修饰，通过一个需要分子氧和铜离子的翻译后事件。多年来，关于在催化过程中利用醌辅因子的机制的丰富知识已经积累起来，并导致了一个建立良好的胺转化为相应醛的模型。尽管如此，对CAO催化前体酪氨酸转化为活性成熟辅因子的策略还缺乏充分的了解。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作用的基本问题，提出的研究的具体目标是(1)评估和鉴定潜在的化学中间体(2)评估铜的亲电性的作用(3)确定亚基间通信在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.