Catalytic Mechanisms of Heme-Copper Oxidases

血红素铜氧化酶的催化机制

基本信息

批准号：
6895418
负责人：
MARIAN FABIAN
金额：
$ 25.66万
依托单位：
RICE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
1998
资助国家：
美国
起止时间：
1998-06-01 至 2007-02-28
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Respiratory oxidases are membrane-bound electron-transfer complexes which catalyze the reduction of molecular dioxygen to water and use the associated free energy changes to generate a transmembrane proton gradient. This proton gradient is the primary source of energy for biological free energy in humans. In recent years it has become apparent that most respiratory oxidases are members of a single family, the heme-copper oxidase super-family. Members of this family have a unique bimetallic center composed of heme plus copper; at this center dioxygen is reduced and high affinity ligands are bound. Cytochrome c oxidase (CcO) catalyzes in one enzymatic cycle the oxidation of four equivalents of ferrocytochrome c located on the cytosolic side of the inner mitochondrial membrane and this oxidation is accompanied by the consumption of four protons from the matrix space to complete the formation of two water molecules. The free energy expended in the formation of water is not dissipated but conserved as a trans-membrane proton gradient with a stoichiometry one proton translocated per electron transferred. The complete conversion of oxygen to water proceeds through specific oxy intermediates corresponding to discrete chemical states of the binuclear center. Despite a large body of valuable knowledge that has been accumulated in recent years the chemical nature of certain of these oxy intermediates is still controversial and very little is known about the proton pumping mechanism per se and the involvement of these intermediates in the pumping process. The objective of this proposal is to establish the nature of selected oxy intermediates, their protonation state, the mechanism and the redox stoichiometry of their interconversion, the relation of these intermediates to the proton pumping activity, to test the hypothesis that the conservation of electroneutrality at the binuclear center is a fundamental requirement and to characterize the mechanism of ligand interaction(s). To address these problems we plan to use isolated mitochondria, purified bovine CcO and CcO incorporated into vesicles. Optical spectroscopy, electron paramagnetic resonance with rapid quenching kinetics, magnetic and natural circular dichroism, resonance Raman spectroscopy, stopped-flow kinetics, and several biochemical methods will be used to accomplish these goals.

描述（由申请人提供）：呼吸氧化酶是膜结合的催化分子双氧还原的电子转移络合物水并利用相关的自由能变化来产生跨膜质子梯度。这种质子梯度是能量的主要来源人类的生物自由能。近年来，已经很明显的是大多数呼吸氧化酶都是血红素铜家族的成员氧化酶超家族。该家族的成员拥有独特的双金属中心由血红素加铜组成；在这个中心，分子氧减少并且很高亲和配体被结合。细胞色素 c 氧化酶 (CcO) 催化一种酶促循环四个当量的铁细胞色素 c 的氧化位于线粒体内膜的胞质侧，这种氧化是伴随着四个质子从矩阵空间的消耗完成两个水分子的形成。消耗的自由能水的形成不会消散，而是作为跨膜质子保存下来每个电子转移一个质子易位的化学计量梯度。氧气完全转化为水是通过特定的氧气进行的对应于双核离散化学态的中间体中心。尽管我们已经积累了大量宝贵的知识近年来，某些含氧中间体的化学性质仍然未得到证实。关于质子泵浦机制存在争议，而且人们知之甚少 se 以及这些中间体在泵送过程中的参与。这该提案的目的是确定选定氧的性质中间体、它们的质子化状态、机理和氧化还原它们相互转化的化学计量，这些中间体与质子泵浦活动，以检验守恒的假设双核中心的电中性是一项基本要求描述配体相互作用的机制。为了解决这些问题我们计划使用分离的线粒体、纯化的牛 CcO 和掺入的 CcO 进入囊泡。光谱、电子顺磁共振快速淬灭动力学、磁性和自然圆二色性、共振拉曼光谱学、停流动力学和几种生化方法将用于实现这些目标。

项目成果

期刊论文数量（14）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Proton involvement in the transition from the "peroxy" to the ferryl intermediate of cytochrome c oxidase.

质子参与细胞色素c氧化酶从“过氧”到ferryl中间体的转变。

DOI：
10.1021/bi002373i
发表时间：
2001
期刊：
Biochemistry
影响因子：
2.9
作者：
Fabian,M;Palmer,G
通讯作者：
Palmer,G

The contributions of G.T. (Jerry) Babcock to our understanding of cytochrome oxidase.

G.T.的贡献

DOI：
10.1016/j.bbabio.2003.05.001
发表时间：
2004
期刊：
Biochimica et biophysica acta
影响因子：
0
作者：
Palmer,Graham
通讯作者：
Palmer,Graham

Two sites of interaction of anions with cytochrome a in oxidized bovine cytochrome c oxidase.

氧化牛细胞色素 c 氧化酶中阴离子与细胞色素 a 相互作用的两个位点。

DOI：
10.1074/jbc.m311834200
发表时间：
2004
期刊：
The Journal of biological chemistry
影响因子：
0
作者：
Fabian,Marian;Jancura,Daniel;Palmer,Graham
通讯作者：
Palmer,Graham

The reactivity of alpha-hydroxyhaem and verdohaem bound to haem oxygenase-1 to dioxygen and sodium dithionite.

α-羟基血红素和维多血红素与血红素加氧酶-1 结合，生成双氧和连二亚硫酸钠。

DOI：
10.1046/j.1432-1033.2002.03230.x
发表时间：
2002
期刊：
European journal of biochemistry
影响因子：
0
作者：
Sakamoto,Hiroshi;Omata,Yoshiaki;Hayashi,Shunsuke;Harada,Saori;Palmer,Graham;Noguchi,Masato
通讯作者：
Noguchi,Masato

Cyanide stimulated dissociation of chloride from the catalytic center of oxidized cytochrome c oxidase.