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Research has been conducted on Rhodobacter sphaeroides heme-copper oxidases with the D-channel. The characterization of the oxidase's mutant has been carried out via the examination of the individual step rates in the catalytic cycle and the results indicate that the nature of the oxygenated intermediates has not been disturbed by the mutant.

Research has been conducted on the electron-transfer from heme a to heme a (sub)3. The rate constant of this transfer and the flash-induced absorbance changes in the fully reduced and mixed-valance enzymes have been investigated and are reported.

Research describes the kinetics of the oxidation of the reduced cytochrome caa(sub)3 of Rhodothermus marinus by molecular oxygen using the flow-flash technique. Results reveal the presence of an additional, fifth electron in the enzyme as shown by two additional kinetic phases.

Research has been conducted on the 'peroxy' (P) intermediate in cytochrome c oxidase. The kinetic and thermodynamic parameters for formation of the cytochrome c oxidase with dioxygen (P (sub)m) and fully reduced enzyme with oxygen (P (sub)r) in the Rhodobacter sphaeroides enzyme are discussed.

Research points out that the origin of the absorbance difference spectrum at high pH is due to the hydroxide-ligated heme a(sub)3, which represents the transition of heme a(sub)3 from a high-spin to a low-spin state. Data suggest that proton pumping may be catalyzed by the free energy of the re-reduction of heme a(sub)3 and protonation of the hydroxyl moiety.

Research discusses the formation of F intermediate at a glutamic-acid residue, (E(I-286) and its reprotonation during proton-transfer reactions in cytochrome c oxidase from Rhodobacter sphaeroides. Data for rates of internal proton transfer from (E(I-286) to the proton acceptor and the influence of pH are presented.