Crystal structure of methyl coenzyme M reductase: The key enzyme of biological methane formation
Crystal structure of methyl coenzyme M reductase: The key enzyme of biological methane formation
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DOI：
10.1126/science.278.5342.1457
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发表时间：
1997-11-21
期刊：
影响因子：
56.9
通讯作者：
Thauer, RK
中科院分区：
文献类型：
--
作者：
Ermler, U;Grabarse, W;Thauer, RK
甲基辅酶M还原酶(MCR)是负责微生物形成甲烷的酶，是一种300千道尔顿的蛋白质，以六聚体的形式在α(2)β(2)伽马(2)排列中组织。热自养甲烷杆菌的酶晶体结构在1.45埃分辨率下确定为失活酶状态MCRox1-Silent，表明镍卟啉辅酶F-430的两个分子嵌入在α、α‘、β和伽马亚基和α’、α、β‘和伽马’亚基之间，形成两个相同的活性部位。底物甲基辅酶M通过与第二底物辅酶B结合后锁定的狭窄通道进入底物甲基辅酶M的每个位置，结合含有辅酶M和B的杂二硫键的第二结构特征酶状态(MCRSilent)，提出了使用自由基中间体和镍有机化合物的反应机理。
Methyl-coenzyme M reductase (MCR), the enzyme responsible for the microbial formation of methane, is a 300-kilodalton protein organized as a hexamer in an alpha(2) beta(2) gamma(2) arrangement. The crystal structure of the enzyme from Methanobacterium thermoautotrophicum, determined at 1.45 angstrom resolution for the inactive enzyme state MCRox1-silent, reveals that two molecules of the nickel porphinoid coenzyme F-430 are embedded between the subunits alpha,alpha',beta, and gamma and alpha',alpha,beta', and gamma', forming two identical active sites. Each site is accessible for the substrate methyl-coenzyme M through a narrow channel locked after binding of the second substrate coenzyme B. Together with a second structurally characterized enzyme state (MCRsilent) containing the heterodisulfide of coenzymes M and B, a reaction mechanism is proposed that uses a radical intermediate and a nickel organic compound.