Bovine heart cytochrome c oxidase is a large multi-component membrane protein containing several phospholipids. X-ray structures of this enzyme at high resolution, determined recently, show a trigonal planar structure of CuB site in the O2 reduction site, which could contribute critically to the four-electron reduction of O2 bound at haem a3, and a hydrogen bond network, through which the proton pump is driven by haem a. The possible roles of phospholipids in the enzyme functions are discussed.
X-ray Crystal Structure of Bovine Heart Cytochrome c Oxidase.