Multinuclear Dioxygen-Utilizing Copper Enzymes: Diverse Roles for Aromatic Redox Active Amino Acids

项目总结 地球上的有氧生命通过不同的范围利用分子氧(O2)的氧化能力 酶协同调节并利用这种高氧化电位来调节大量的氧化转化 在新陈代谢过程中。其中许多辅因子是由两个金属中心组成的偶联双核中心 比如铜和铁的距离很近。该提案详细介绍了以下领域的基础研究 ，旨在解决有关氧化还原的潜在作用的几个有趣的问题 芳香族活性氨基酸如酪氨酸和色氨酸链在酶中的作用机制和功能。 我们鉴定了三种不同类型的利用氧气的铜酶，包括细胞色素c氧化酶(Cco)。 它将O2还原为水，多铜氧化酶(MCO)将该反应耦合到四个单电子 底物的氧化，以及一类新的铜酶，称为Burp结构域环化酶，它催化 多肽底物中Tyr/Trp链的2-电子氧化大环化。 底物或末端电子受体已在这些酶中建立，但Burp结构域除外 酶的作用还有待确认。 在所有这三类中，适当调整和定位的Tyr/Trp链扮演着不同的角色 活动站点的组成部分(即CcO)，或者他们可以被分配一个调停角色以提供替代方案 氧化更具挑战性的底物(即MCO)的途径。它们甚至可以作为直接的底物 活性部位(即铜依赖的Burp结构域环化酶)。在所有情况下，尽管它们的使用方式多种多样 它们的主要功能是微妙地提供氧气还原所需的电子/质子。这些是怎么回事 残留物是为特定功能设计/优化的吗？它们之间有什么相同点和不同点 酵素？我们的研究旨在揭示这些Tyr/Trp链在酶功能和 机制，并解决了铜的生物化学和有氧代谢的一些问题。

PROJECT SUMMARY Aerobic life on earth harnesses the oxidizing power of molecular oxygen (O2) through a diverse range of enzyme cofactors and employs that high oxidation potential to mediate numerous oxidative transformations during metabolic functions. Many of these cofactors are coupled binuclear sites consisting of two metal centers such as copper and iron in close proximity. This proposal details fundamental research in the field of bioinorganic chemistry and aims to address several intriguing questions about the potential roles of redox aromatic active amino acids such as tyrosine and tryptophane chains in the enzyme mechanism and function. We identified three different classes of O2-utilizing copper enzymes including cytochrome c oxidase (CcO) which reduces O2 to water, multicopper oxidase (MCO) which couples that reaction to four one-electron oxidations of the substrates, and a new class of copper enzymes called BURP domain cyclases which catalyze 2-electron oxidative macrocyclization of the Tyr/Trp chains in peptide substrates.The use of O2 as either a substrate or terminal electron acceptor has been established in these enzymes except for the BURP domain enzymes which is yet to be confirmed. In all three classes, appropriately tuned and positioned Tyr/Trp chains play different roles either as an integral part of the active site (i.e., CcO) or they may be assigned a mediatory role to provide an alternative path for oxidation of the more challenging substrates (i.e., MCO). They may even act as the direct substrate for the active site (i.e., Cu-dependent BURP domain cyclases). In all cases, despite the diverse use of these chains, their main function is to delicately supply the electron/proton needed for the O2 reduction. How are these residues designed/optimized for a particular function? What are the similarities and differences between these enzymes? Our studies aim to reveal the potential role of these Tyr/Trp chains play in enzymatic function and mechanism and address some of the questions about copper biochemistry and aerobic metabolism.