Turnover of cytochrome c oxidase from Paracoccus denitrificans

The heme aa3 type cytochrome oxidase from Paracoccus denitrificans incorporated into vesicles with phospholipid reacts during turnover much as the oxidase from mitochondria does. The spectrophotometric changes observed at various wavelengths are closely similar, and the rate is about one-half of that for beef heart oxidase under the same conditions. The rate of appearance of oxidized cytochrome c on initiation of the reaction is also similar and depends on the previous treatment of the oxidase as described by Antonini, E., Brunori, M., Colosimo, A., Greenwood, C. and Wilson, M. T. (1977) Proc. Natl. Acad. Sci. U.S.A. 74, 3128-3132. In terms of their model the resting Paracoccus enzyme is converted to the pulsed form during turnover. The effect is observed with both cytochrome c and hexamine ruthenium as reductants. With the latter a 60-fold increase in rate is observed.