M. Sharpe et al., ACTION OF BOVINE SERUM-ALBUMIN ON CYTOCHROME-C-OXIDASE ACTIVITY AND PROTON-PUMPING - A ROLE FOR FATTY-ACIDS IN ENZYME FUNCTION, FEBS letters, 391(1-2), 1996, pp. 134-138
Bovine serum albumin (BSA) at micromolar concentrations causes a red s
hift of the Soret band of bovine cytochrome c oxidase with a slow biph
asic time course. It also inhibits the turnover of detergent-isolated
enzyme in a similarly slow manner; the progress of this inhibition is
halted by palmitate and other fatty acids. The inhibitory bovine serum
albumin effect may involve fatty acid depletion from the enzyme. Resp
iration by cytochrome c oxidase vesicles (proteoliposomes) in the pres
ence of ionophores (uncontrolled) shows only a small inhibition by BSA
but preincubation of such vesicles with BSA induces a loss of proton
pumping activity, After incubation of BSA-depleted proteoliposomes in
the presence of reductant with combinations of fatty acids, pumping ac
tivity can be fully restored, suggesting a supportive or even essentia
l role of endogenous fatty acids in H+ translocation by this membranou
s enzyme.