Redox potentiometry studies of particulate methane monooxygenase: Support for a trinuclear copper cluster active site
Redox potentiometry studies of particulate methane monooxygenase: Support for a trinuclear copper cluster active site
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DOI：
10.1002/anie.200604647
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发表时间：
2007-01-01
影响因子：
16.6
通讯作者：
Chan, Michael K.
中科院分区：
文献类型：
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作者：
Chan, Sunney I.;Wang, Vincent C-C;Chan, Michael K.
颗粒甲烷单加氧酶(PMMO)是一种复杂的膜蛋白(ABG)，在我们手中(见下文)，包含大约15个铜离子，[1，2]隔离成催化三核铜簇(C簇)和电子转移铜离子，称为E簇。[3，4]我们提出C簇介导烷烃羟基化和氧气还原化学，而E簇提供还原当量的缓冲，以在周转过程中迅速重新还原C簇铜离子。在这里，我们为我们的假设提供了额外的支持，即三核铜团簇是pMMO的羟基化中心。[4]在pMMO富集膜中，分离的pMMO的EPR谱通常由信号的叠加组成：在Gav2.12时是经典的2型CuII信号，在平行区具有Cu超精细结构(gk=2.24)，在垂直区具有14N超精细结构(g？=2.059)，以及几乎没有特征的各向同性信号，我们将其归类为三核CuIICuIICuII团簇。[4，5]与类型2CuII信号不同，在高微波功率下，星团的信号不会饱和。
Particulate methane monooxygenase (pMMO) is a complex membrane protein (abg) that—in our hands (see below)—contains approximately 15 copper ions,[1, 2] sequestered into catalytic trinuclear copper clusters (C clusters) and electrontransfer copper ions known as Eclusters.[3, 4] We have proposed that the C clusters mediate alkane hydroxylation and dioxygen reduction chemistry, while the Eclusters provide a buffer of reducing equivalents to rapidly rereduce the C cluster copper ions during turnover. Herein, we provide additional support for our hypothesis of a trinuclear copper cluster as the hydroxylation site of pMMO.[4]The EPR spectrum for the as-isolated pMMO in pMMO-enriched membranes typically consists of a superposition of signals: a classical type 2 CuII signal at gav% 2.12, with Cu hyperfine structure in the parallel region (gk= 2.24) and 14Nsuperhyperfine structure in the perpendicular region (g?= 2.059), and an almost featureless isotropic signal centered at g% 2.1 that we have assigned to a trinuclear CuIICuIICuII cluster.[4, 5] Unlike the type2 CuII signal, the signal of the cluster does not saturate at high microwave power.[5]