A two-subunit cytochrome c oxidase (cytochrome aa3) from Paracoccus dentrificans.

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Abstract
Cytochrome c oxidase (ferrocytochrome c: oxygen oxidoreductase, EC 1.9.3.1) was purified from the cytoplasmic membrane of the bacterium P. denitrificans. The enzyme contains 2 heme groups (a and a3) and 2 Cu atoms/minimal unit, oxidizes mammalian cytochrome c at a high rate, and, when incorporated into liposomes, generates an electrochemical proton gradient during cytochrome c oxidation. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis reveals only 2 subunits of apparent MW 45,000 and 28,000; they appear to correspond to the 2 largest mitochondrially made subunits of the 7-subunit cytochrome c oxidase isolated from yeast mitochondria. Because of its structural simplicity, P. cytochrome c oxidase offers new possibilities for exploring the mechanism of cytochrome c oxidase function.