Could Cu sub(B) be the site of redox linkage in cytochrome c oxidase?

This paper explores the proton pumping function of cytochrome c oxidase (ferrocytochrome-c:oxygen oxido-reductase (EC 1.9.3.1)) based upon redox linkage at the "high-potential" Cu sub(B) center. A model is proposed that is derived from a redox-linked ligand exchange mechanism previously described for the Cu sub(A) site. Qualitative analysis of this mechanism indicates that such a mechanism is feasible. The relatively short distance between Cu sub(B) and cytochrome a sub(3) implies that the uncoupling electron transfers are quite facile. The position of the Cu sub(B) center with respect to the inner mitochondrial membrane argues against redox linkage at the Cu sub(B) site.