CYTOCHROME-C BINDING-SITE ON CYTOCHROME-C OXIDASE

Cytochrome c was chemically coupled to cytochrome c oxidase using the reagent 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) which couples amine groups to carboxyl residues. The products of this reaction were analyzed on 2.5-27% polyacrylamide gradient gels electrophoretically. Since cytochrome c binds to cytochrome oxidase electrostatically in an attraction between certain of its lysine residues and carboxyl residues on the oxidase surface, EDC is an especially appropriate reagent probe for binding-subunit studies. Coupling of polylysine to cytochrome oxidase using EDC was also performed, and the products of this reaction indicate that polylysine, an inhibitor of the cytochrome c reaction with oxidase, binds to the same oxidase subunit as does cytochrome c, subunit IV in the gel system used. © 1979.