Characterisation of a near infra‐red absorption band of the Escherichia coli quinol oxidase, cytochrome o, which is attributable to the high‐spin ferrous haem of the binuclear site

FEBS Letters

Ingledew, W.John¹  Bacon, Mark¹  Rich, Peter R.² 

[1] Department of Biochemistry and Microbiology, University of St. Andrews, St. Andrews, Fife, KY16 9AL, Scotland, UK;Glynn Research Institute, Bodmin, Cornwalt, PL30 4AU, England, UK

关键词: Cytochrome o;    Quinol oxidase;    Oxygen reduction;    Respiratory chain;    Oxidative phosphorylation;    Escherichia coli;   

DOI  :  10.1016/0014-5793(92)80658-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The bacterial quinol oxidase, cytochrome o, is an enzyme which is highly analogous to the better known cytochrome c oxidase, cytochrome aa₃ but with the important difference that it lacks the near infra-red absorbing pigment Cu_A. In this article we report an absorption band in the near IR spectrum of cytochrome o with a maximal absorption at 738 nm, and which is attributable to the ferrous high-spin haem. The 758 nm band has an extinction coefficient or 0.2–0.3 mM⁻¹·cm⁻¹ at 758–800 nm. This region in cytochrome aa₃ , is dominated by the Cu_A absorption. The 758 nm absorption is lost on addition of CO or cyanide to the reduced enzyme. The carbon monoxide compound of cytochrome o also has absorbance bands in the near infra-red, and these may be attributable to a low-spin ferrous haem compound.

【 授权许可】

Unknown