X-RAY CRYSTALLOGRAPHIC STUDIES OF METHANE MONOOXYGENASE

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。可溶性甲烷单加氧酶（Soluble methane monooxygenase，sMMO）是甲烷氧化菌中催化甲烷氧化为甲醇的四组分酶系统。催化作用发生在羟化酶（MMOH）组分的α亚基中的羧基桥连双核铁中心。动力学和光谱研究表明，对接的耦合蛋白（MMOB）与MMOH提高了反应速率，并改变了二铁中心的光谱特性。这些变化的原因尚不清楚。MMOD是一种新发现的在sMMO操纵子中编码的蛋白质，其改变MMOH二铁中心的光谱性质，与a亚基交联，并通过与MMOB竞争结合来抑制羟化酶活性。目前尚不清楚MMOD如何改变二铁中心的性质或抑制活性。目前的研究旨在确定MMOH-MMOB和MMOH-MMOD复合物的结构，并在各种条件下探测MMOH的二铁位点的结构细节。

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. Soluble methane monooxygenase (sMMO) is a four-component enzyme system that catalyzes the oxidation of methane to methanol in methanotrophic bacteria. Catalysis occurs at a carboxylate-bridged dinuclear iron center in the a subunit of the hydroxylase (MMOH) component. Kinetic and spectroscopic studies have shown that the docking of the coupling protein (MMOB) with MMOH enhances the reaction rate and alters the spectroscopic properties of the diiron center. The reasons for these changes are unknown. MMOD, a newly discovered protein encoded in the sMMO operon, alters the spectroscopic properties of the MMOH diiron center, cross-links to the a subunit, and inhibits hydroxylase activity by competing with MMOB for binding. It is unknown how MMOD alters the properties of the diiron center or inhibits activity. Current studies are aimed at determining the structures of the MMOH-MMOB and MMOH-MMOD complexes and probing structural details of the diiron site of MMOH under various conditions.