Crystallization of bovine heart mitochondrial cytochrome c oxidase for X-ray diffraction at atomic resolution (2.8 angstrom)

Four types of crystals were obtained from bovine heart cytochrome c oxidase (ferrocytochrome c: oxygen oxidoreductase, EC 1.9.3.1.), a large multicomponent membrane protein. Three of these crystals (hexagonal bipyramidal, tetragonal plate, and tetragonal column) were obtained from an enzyme preparation stabilized with alkyl polyethelene glycol monoether-type detergents. The tetragonal column crystals diffracted X-rays up to 5 Angstrom resolution, but this is far lower than the atomic resolution. The orthorhombic crystals have been obtained from an enzyme preparation stabilized with decyl beta-D-maltoside, which diffracted X-rays up to 2.6 Angstrom resolution. Crystals sufficient for X-ray diffraction experiments had not been obtained from enzyme preparations using any other alkyl-sugar-type detergent commercially available. These results suggest that crystallization of many membrane proteins to achieve the atomic resolution level is possible if a detergent of appropriate structure is available.