Spectroscopic evidence for a heme-superoxide/Cu(I) intermediate in a functional model of cytochrome C oxidase

被引：53
作者：
Collman, JP [1 ]
Sunderland, CJ [1 ]
Berg, KE [1 ]
Vance, MA [1 ]
Solomon, EI [1 ]
机构：
[1] Stanford Univ, Dept Chem, Stanford, CA 94305 USA
来源：
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY | 2003年 / 125卷 / 22期
关键词：
D O I：
10.1021/ja034382v
中图分类号：
O6 [化学];
学科分类号：
0703 ;
摘要：
A superstructured tetraphenylporphyrin with a covalently attached proximal imidazole axial base and three distal imidazole pickets has been developed as a model for the active site of terminal oxidases such as cytochrome c oxidase. The oxygen adduct of the Fe-only heme (at low temperature) has a diamagnetic NMR and is EPR silent, which taken together with a resonance Raman oxygen isotope sensitive band (νFe-O) at 575/554 cm-1 (16O2/18O2) indicates formation of a six-coordinate heme-superoxide complex. Unexpectedly, the Fe/Cu complex, where the copper is in a trisimidazole environment ∼5 Å above the heme plane, displays similar characteristics: a diamagnetic NMR, EPR silence, and νFe-O at 570/544 cm-1. This indicates the dioxygen adduct of this Fe/Cu system is also a superoxide. This contrasts with previously characterized partially reduced dioxygen intermediates of binuclear heme/copper complexes that form Fe/Cu μ-peroxo complexes. Copyright © 2003 American Chemical Society.
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页码：6648 / 6649
页数：2
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