Effect of papain digestion on redox-linked proton translocation in b-c1 complex from beef heart reconstituted into liposomes.
Papain treatment of the cytochrome b-c1 complex from beef heart results in partial proteolysis of core protein II, the iron-sulphur protein and the 15-kDa subunit. Under these conditions a significant inhibition of electron flow and complete suppression of proton translocation in the complex reconstituted into liposomes are observed. Kinetic experiments indicate a correlation between the digestion of core protein II and 15-kDa subunit and the suppression of proton translocation. The results suggest an active involvement of polypeptides of the complex in stabilizing the semiquinone species and/or providing pathways to exchange protons between bound quinone systems and aqueous phases.
Lorusso
M
M
Gatti
D
D
Marzo
M
M
Papa
S
S
D000818:Animals; D002417:Cattle; D004579:Electron Transport / Q000187:drug effects; D014450:Electron Transport Complex III; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism; D007700:Kinetics; D008081:Liposomes / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000378:metabolism*; D009206:Myocardium / Q000201:enzymology*; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D010084:Oxidation-Reduction; D010206:Papain / Q000494:pharmacology*; D010446:Peptide Fragments / Q000378:metabolism; D011522:Protons; D011808:Quinone Reductases / Q000378:metabolism*
D007473:Ion Channels; D008081:Liposomes; D009097:Multienzyme Complexes; D010446:Peptide Fragments; D011522:Protons; D009247:NADH, NADPH Oxidoreductases; D011808:Quinone Reductases; D010206:Papain; D014450:Electron Transport Complex III