Orientation of the haems of the ubiquinol oxidase: O2 reductase, cytochrome bo of Escherichia coli

Abstract

The orientation of the two haems of the Escherichia coli ubiquinol oxidase:O2 reductase, cytochrome bo, has been determined by electron paramagnetic resonance studies on oriented multilayer preparations of cytoplasmic membrane fragments. The enzyme contains a low‐spin b‐like haem and a high‐spin b‐like haem, designated cytochromes b and o respectively. Both haems are oriented with their planes perpendicular to the membrane plane, further extending the catalogue of structural and functional similarities between this enzyme and the mammalian cytochrome c oxidase, cytochrome aa3. Copyright © 1991, Wiley Blackwell. All rights reserved