Distinct forms of the haem o‐Cu binuclear site of oxidised cytochrome bo from Escherichia coli

FEBS Letters

Watmough, Nicholas J.³  Gennis, Robert B.²  Cheesman, Myles R.³  Greenwood, Colin¹  Thomson, Andrew J.³ 

[1] Centre for Metalloprotein Spectroscopy and Biology, School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK;Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA;Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences, University of East Anglia, Norwich NR4 7TJ, UK

关键词: Cytochrome bo;    Cytochrome c oxidase;    EPR;   

DOI  :  10.1016/0014-5793(93)80056-Z

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Oxidised, formate-bound and fluoride-bound forms of E. coli cytochrome bo give rise to an electronic absorption band near 630 nm, diagnostic of high-spin ferrric haem o, whose position is sensitive to the nature of the bound anion. In all three forms, haem o remains spin-coupled to cu_B(II), resulting in distinct broad X-band EPR signals. Those of formate-bound cytochrome bo are similar to the signals seen in slow cytochrome aa ₃ but cannot be induced by incubation at acid pH suggesting that the endogenous earboxylate believed to be important in slow cytochrome aa ₃ is not present in cytochrome bo. The oxidised form gives rise to novel EPR signals at g = 3.74 and g = 3.08 which have not been detected in cytochrome aa ₃ and may arise from a weak magnetic coupling between high-spin haem o, S = 5/2, and Cu_b(ii), S = ½.

【 授权许可】

Unknown