Preliminary studies on the crystallization of beef heart cytochrome c oxidase by vapor diffusion

Beef heart cytochrome c oxidase has been crystallized in its native and delipidated forms, using the hanging drop vapor diffusion method. The delipidated oxidase, which is subunit III deficient, can be crystallized in rosettes using this method from a medium containing zinc chloride as well as ammonium sulfate. The crystals give a protein 'powder' pattern on preliminary X-ray analysis. The crystals initially grow rapidly but stop growing at a small size probably as a result of addition of heterogeneous material at the crystal surface.