Abstract:
Studies on the steady state behavior of soluble cytochrome c oxidase are
extensive. These studies have examined the influence of ionic strength and pH
and may provide answers to questions such as the link between proton
translocation and charge separation. The present study examined the influence
of external bulk pH on ApH formation, biphasic kinetics, and steady state
reduction of cytochromes c and a of cytochrome c oxidase in proteoliposomes.
Bulk pH has an appreciable effect on ApH formation and steady state reduction
levels of cytochromes c and 8. Bulk pH affected total Vmax and Km at the low
affinity binding site of cytochrome c. This study also examined the influence of
bovine serum albumin and free fatty acids on proton pumping activity in bovine
heart proteoliposomes. Proton pumping activity decreased after treatment with
BSA, and was subsequently reinstated after further treatment with FFA.
Much study in the superfamily of haem/copper oxidases has recently
been devoted to the bacterial oxidases. The present study has examined some
protein composition characteristics and bioenergetic features of Bacillus subtilis
cytochrome caa3 oxidase. Results provide evidence for the structural
composition of the enzyme in relation to the covalently bound cytochrome c to
the oxidas~. Bioenergetically, caa3 COV showed appreciable proton pumping
activity. Steady state analysis of the caa3 COV showed significantly different
cytochrome c and a reduction characteristics compared to the bovine enzyme.
