Electron transfer to the active site of the bacterial nitric oxide reductase is controlled by ligand binding to heme b3.
Electron transfer to the active site of the bacterial nitric oxide reductase is controlled by ligand binding to heme b3.
复制标题
电子转移到细菌一氧化氮还原酶的活性位点是由与血红素 b3 结合的配体控制的。
DOI：
10.1016/j.bbabio.2011.01.009
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
Field SJ
中科院分区：
文献类型：
--
作者：
Field SJ
副球菌（Paracoccus）一氧化氮还原酶的活性中心含有一个由血红素b3和非血红素铁（FeB）组成的双核中心。这些金属中心被证明处于等电位，中点还原电位为Em +80 mV。在酶中的其他两个金属中心，血红素c和血红素B，的中点还原电位大于双核中心，这表明它们作为一个电子接收/存储模块。低自旋血红素B的还原导致双核中心的结构变化，从而允许接近底物分子。在底物类似物CO存在下，血红素b3的中点还原电位升高到与血红素c和血红素B相似的区域。这使我们提出，电子转移血红素的还原导致活性位点的开放，这允许底物结合，并进而提高活性位点的还原电位，使得电子仅在底物结合后被递送到活性位点。
The active site of the bacterial nitric oxide reductase from Paracoccus denitrificans contains a dinuclear centre comprising heme b3and non heme iron (FeB). These metal centres are shown to be at isopotential with midpoint reduction potentials of Em≈+80mV. The midpoint reduction potentials of the other two metal centres in the enzyme, heme c and heme b, are greater than the dinuclear centre suggesting that they act as an electron receiving/storage module. Reduction of the low-spin heme b causes structural changes at the dinuclear centre which allow access to substrate molecules. In the presence of the substrate analogue, CO, the midpoint reduction potential of heme b3is raised to a region similar to that of heme c and heme b. This leads us to suggest that reduction of the electron transfer hemes leads to an opening of the active site which allows substrate to bind and in turn raises the reduction potential of the active site such that electrons are only delivered to the active site following substrate binding.