Discrimination between two possible reaction sequences that create potential risk of generation of deleterious radicals by cytochrome bc₁. Implications for the mechanism of superoxide production.

ABSTRACT: In addition to its bioenergetic function of building up proton motive force, cytochrome bc₁ can be a source of superoxide. One-electron reduction of oxygen is believed to occur from semiquinone (SQ(o)) formed at the quinone oxidation/reduction Q(o) site (Q(o)) as a result of single-electron oxidation of quinol by the iron-sulfur cluster (FeS) (semiforward mechanism) or single-electron reduction of quinone by heme b(L) (semireverse mechanism). It is hotly debated which mechanism plays a major role in the overall production of superoxide as experimental data supporting either reaction exist. To evaluate a contribution of each of the mechanisms we first measured superoxide production under a broad range of conditions using the mutants of cytochrome bc₁ that severely impeded the oxidation of F

SUBMITTER: Sarewicz M 

PROVIDER: S-EPMC3057645 | biostudies-literature | 2010 Nov

REPOSITORIES: biostudies-literature