通过X射线吸收光谱法测定单独的甲烷单加氧酶羟化酶氧化形式以及在MMOD存在下的铁-铁分离情况。
Determination by X-ray absorption spectroscopy of the Fe-Fe separation in the oxidized form of the hydroxylase of methane monooxygenase alone and in the presence of MMOD.
作者信息
Rudd Deanne Jackson, Sazinsky Matthew H, Merkx Maarten, Lippard Stephen J, Hedman Britt, Hodgson Keith O
机构信息
Departments of Chemistry, Stanford University, Stanford, California 94305, USA.
出版信息
Inorg Chem. 2004 Jul 26;43(15):4579-89. doi: 10.1021/ic049716b.
The diiron active site in the hydroxylase of Methylococcus capsulatus (Bath) methane monooxygenase (MMOH) has been studied in the oxidized form by X-ray absorption spectroscopy (XAS). Previous investigations by XAS and X-ray crystallography have identified two different distances (3.0 and 3.4 angstroms) between the two Fe atoms in the dinuclear site. The present study has employed a systematic extended X-ray absorption fine structure (EXAFS) fitting methodology, utilizing known and simulated active site and relevant model structures, to determine unambiguously the Fe-Fe separation in the oxidized form of MMOH. Consistent and unique fits were only possible for an Fe-Fe distance of 3.0 angstroms. This methodology was then applied to study potential changes in the active site local structure in the presence of MMOD, a protein of unknown function in multicomponent MMO. Fe K-edge and EXAFS analyses revealed negligible changes in the diiron site electronic and geometric structure upon addition of MMOD to oxidized MMOH.
利用X射线吸收光谱（XAS）对荚膜甲基球菌（巴斯）甲烷单加氧酶（MMOH）羟化酶中的双铁活性位点进行了氧化态研究。先前通过XAS和X射线晶体学研究已确定双核位点中两个铁原子之间存在两种不同距离（3.0和3.4埃）。本研究采用了系统的扩展X射线吸收精细结构（EXAFS）拟合方法，利用已知和模拟的活性位点及相关模型结构，明确确定MMOH氧化态中的铁-铁间距。只有在铁-铁距离为3.0埃时才能得到一致且唯一的拟合结果。然后将该方法应用于研究多组分MMO中功能未知的蛋白质MMOD存在时活性位点局部结构的潜在变化。铁K边和EXAFS分析表明，向氧化态MMOH中添加MMOD后，双铁位点的电子和几何结构变化可忽略不计。
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