Electron-transfer pathways in the heme and quinone-binding domain of complex II (succinate dehydrogenase).

ABSTRACT: Single electron transfers have been examined in complex II (succinate:ubiquinone oxidoreductase) by the method of pulse radiolysis. Electrons are introduced into the enzyme initially at the [3Fe-4S] and ubiquinone sites followed by intramolecular equilibration with the b heme of the enzyme. To define thermodynamic and other controlling parameters for the pathways of electron transfer in complex II, site-directed variants were constructed and analyzed. Variants at SdhB-His207 and SdhB-Ile209 exhibit significantly perturbed electron transfer between the [3Fe-4S] cluster and ubiquinone. Analysis of the data using Marcus theory shows that the electronic coupling constants for wild-type and variant enzyme are all small, indicating that electron transfer occurs by diabatic tunneling. The presenc

SUBMITTER: Anderson RF 

PROVIDER: S-EPMC3985935 | biostudies-literature | 2014 Mar

REPOSITORIES: biostudies-literature