Effect of papain digestion on redox-linked proton translocation inb-c1complex from beef heart reconstituted into liposomes

Open Access
Publisher Website
Google Scholar
Abstract
Papain treatment of the cytochrome b‐c 1 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.