Activation and catalysis of the di-heme cytochrome c peroxidase from Paracoccus pantotrophus
Activation and catalysis of the di-heme cytochrome c peroxidase from Paracoccus pantotrophus
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DOI：
10.1016/j.str.2005.09.011
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发表时间：
2006-01-01
期刊：
影响因子：
5.7
通讯作者：
Fulop, V
中科院分区：
文献类型：
--
作者：
Echalier, A;Goodhew, CF;Fulop, V
细菌细胞色素c过氧化物酶含有一个电子转移(E)亚铁血红素结构域和一个过氧化(P)亚铁血红素结构域。除一种酶外，所有这些酶都是以不活跃的氧化状态分离出来的，需要用一个小的氧化还原供体蛋白还原E血红素以激活P血红素。在这里，我们提出了无活性的氧化和活性的泛养副扇贝混合价酶的结构。前者的链柔性由晶体温度因子表示，显著分布在某些环区，这些环区与形成活性混合价酶时发生构象变化的区域相吻合。在这些变化的基础上，我们假设发生了一系列事件，将来自伪天青素或细胞色素C-550的电子进入E亚铁血红素的触发与P亚铁血红素上一个协调组氨酸的解离联系在一起，这允许底物访问。
Bacterial cytochrome c peroxidases contain an electron transferring (E) heme domain and a peroxidatic (P) heme domain. All but one of these enzymes are isolated in an inactive oxidized state and require reduction of the E heme by a small redox donor protein in order to activate the P heme. Here we present the structures of the inactive oxidized and active mixed valence enzyme from Paracoccus pantotrophus. Chain flexibility in the former, as expressed by the crystallographic temperature factors, is strikingly distributed in certain loop regions, and these coincide with the regions of conformational change that occur in forming the active mixed valence enzyme. On the basis of these changes, we postulate a series of events that occur to link the trigger of the electron entering the E heme from either pseudoazurin or cytochrome C-550 and the dissociation of a coordinating histidine at the P heme, which allows substrate access.