ULTRA-HIGH RESOLUTION STRUCTURE OF NATIVE AND ENZYME INTERMEDIATE OF CYTOCHROME

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。酵母中的细胞色素c过氧化物酶（CcP）是一种可溶性含血红素的蛋白质，存在于线粒体电子传递链中，它可能保护细胞免受有毒过氧化物的侵害。它催化两分子铁细胞色素c氧化为铁细胞色素c，同时将过氧化氢还原为水。在与过氧化氢的反应循环过程中，形成半稳定的中间体化合物I，其半衰期约为6小时。化合物I含有以Trp191为中心的半稳定自由基和氧铁基（Fe4+=O）血红素基团。本研究的目的是获得天然CcP及其酶中间体化合物I的接近原子分辨率的可靠结构，从而研究与底物反应的结构细节，并确定常规方法无法确定的Trp191自由基的性质。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Cytochrome c peroxidase (CcP) from yeast is a soluble heme-containing protein found in the mitochondrial electron transport chain where it probably protects against toxic peroxides. It catalyzes the oxidation of two molecules of ferrocytochrome c to ferricytochrome c concomitant with the reduction of hydrogen peroxide to water. During the course of the reaction cycle with hydrogen peroxide it forms a semi-stable intermediate termed Compound I, which has a half-life of about 6 h. The Compound I contains a semi-stable radical centered on Trp191 and an oxyferryl (Fe4+=O) heme group. The aim of this study is to obtain a reliable structure of the native CcP and its enzyme intermediate Compound I to near atomic resolution so as to study the structural details of the reaction with substrates and to determine the nature of Trp191 radical which cannot be determined by conventional methods.