Nature of the Ferryl Heme in Compounds I and II
Nature of the Ferryl Heme in Compounds I and II
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DOI：
10.1074/jbc.m110.183483
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发表时间：
2011-01-14
影响因子：
4.8
通讯作者：
Moody, Peter C. E.
中科院分区：
文献类型：
--
作者：
Gumiero, Andrea;Metcalfe, Clive L.;Moody, Peter C. E.
血红素酶在生物学中普遍存在，并催化大量的生物氧化还原过程。血红素铁的高价铁基中间体（称为化合物I和化合物II）的形成涉及许多催化血红素酶，但这些物质仅瞬时形成，因此已证明有些难以捉摸。因此，关于这些铁基中间体在许多不同血红素酶中的性质，特别是血红素铁和结合氧原子之间的键的确切性质，存在相互矛盾的证据。在这项工作中，我们提出了两种不同的血红素过氧化物酶，细胞色素c过氧化物酶和抗坏血酸过氧化物酶的化合物I和化合物II的中间体的高分辨率晶体结构，允许直接和准确的比较在不同的中间体的键合相互作用。在所有结构中出现一致的图片，显示在化合物I还原为化合物II时铁氧键的延长（和推测的质子化）。这些数据澄清了这些中间体中铁基血红素物质性质的长期不一致性。
Heme enzymes are ubiquitous in biology and catalyze a vast array of biological redox processes. The formation of high valent ferryl intermediates of the heme iron (known as Compounds I and Compound II) is implicated for a number of catalytic heme enzymes, but these species are formed only transiently and thus have proved somewhat elusive. In consequence, there has been conflicting evidence as to the nature of these ferryl intermediates in a number of different heme enzymes, in particular the precise nature of the bond between the heme iron and the bound oxygen atom. In this work, we present high resolution crystal structures of both Compound I and Compound II intermediates in two different heme peroxidase enzymes, cytochrome c peroxidase and ascorbate peroxidase, allowing direct and accurate comparison of the bonding interactions in the different intermediates. A consistent picture emerges across all structures, showing lengthening of the ferryl oxygen bond (and presumed protonation) on reduction of Compound I to Compound II. These data clarify long standing inconsistencies on the nature of the ferryl heme species in these intermediates.