Ilicicolin Inhibition and Binding at Center N of the Dimeric Cytochrome bc1 Complex Reveal Electron Transfer and Regulatory Interactions between Monomers.

ABSTRACT: We have determined the kinetics of ilicicolin binding and dissociation at center N of the yeast bc(1) complex and its effect on the reduction of cytochrome b with center P blocked. The addition of ilicicolin to the oxidized complex resulted in a non-linear inhibition of the extent of cytochrome b reduction by quinol together with a shift of the reduced b(H) heme spectrum, indicating electron transfer between monomers. The possibility of a fast exchange of ilicicolin between center N sites was excluded in two ways. First, kinetic modeling showed that fast movement of an inhibitor between monomers would result in a linear inhibition of the extent of cytochrome b reduction through center N. Second, we determined a very slow dissociation rate for ilicicolin (k = 1.2 x 10(-3) s(-1)) as calculat

SUBMITTER: Covian R 

PROVIDER: S-EPMC2659220 | biostudies-literature | 2009 Mar

REPOSITORIES: biostudies-literature