title: Quaternary structure of bovine cytochrome oxidase.
abstract: A hydrodynamically homogeneous preparation of bovine mitochondrial cytochrome c oxidase can be obtained by anion-exchange chromatography of alkaline-treated enzyme, followed by a gel permeation chromatography step, which further removes some (aggregated) apoprotein. The molecular weight, Mr, of the monodisperse enzyme in Triton X-100 was found to be 210000. This complex is composed of six different polypeptides, with Mr summing up to about 110000 in toto, in a relative one-to-one stoichiometry. Two sets of these subunits constitute the 210000-Mr enzyme complex. In contrast to our earlier report [Saraste, Penttilä, Coggins, and Wikström, FEBS Lett. 114 (1980) 35-38] the 210000-Mr enzyme contains four (and not two) haems A, and therefore represents the dimer of cytochrome aa3. One of the proposed seven subunits, number III, is lacking in this enzyme preparation.
mesh_terms: D000818:Animals; D002417:Cattle; D003902:Detergents; D003576:Electron Transport Complex IV; D046911:Macromolecular Substances; D008929:Mitochondria, Heart / Q000201:enzymology*; D008970:Molecular Weight; D017830:Octoxynol; D011092:Polyethylene Glycols; D011487:Protein Conformation
chemical_list: D003902:Detergents; D046911:Macromolecular Substances; D011092:Polyethylene Glycols; D017830:Octoxynol; D003576:Electron Transport Complex IV