Quinol binding sites and ubisemiquinone stabilisation in the Escherichia coli quinol oxidase, cytochrome bo3. A discussion of models for structure and function

Abstract

The mitochondrial cytochrome bc,-complex, an oligomeric membrane protein. i s one o f the fundamental components of the respiratory chain. I t catalyzes electron transfer from ubiquinol to cytochrome c, while the process is coupled to electrogenic translocation of protons across the inner mitochondrial membrane. The proton-motive Q cycle is a widely accepted model for the functioning of this complex. We study the cytochrome bc,complex from the yeast S. cerevisine as a model system. Knowledge of the high resolution structure of the yeast protein allows a combined approach of X-ray crystallography, biochemical analysis, site-directed mutagenesis and spcctroscopy to study mechanism and structure-function relationship o f this important membrane protein.Crystallization o f the yeast cytochrome bc,-complex was acchieved by co-