Crystal Structure of an Active Form of Monomeric Cytochrome c Oxidase from Bovine Heart

Abstract

Cytochrome c oxidase in the mitochondrial respiratory chain mostly exists as an independent monomer, or as a monomer associated with the complexes I and III in the supercomplex, although its molecular mechanism has been elucidated based on the crystal structure of its dimeric form. Here, we report detailed comparison of the activity and crystal structure between the monomer and the dimer, and the possibility that the monomer is an activated form, whereas the dimer can be regarded as a physiological standby form in the mitochondrial membrane.