Effect of famoxadone on photoinduced electron transfer between the iron-sulfur center and cytochrome c1 in the cytochrome bc1 complex.

Journal Article (Journal Article)

Famoxadone is a new cytochrome bc(1) Q(o) site inhibitor that immobilizes the iron-sulfur protein (ISP) in the b conformation. The effects of famoxadone on electron transfer between the iron-sulfur center (2Fe-2S) and cyt c(1) were studied using a ruthenium dimer to photoinitiate the reaction. The rate constant for electron transfer in the forward direction from 2Fe-2S to cyt c(1) was found to be 16,000 s(-1) in bovine cyt bc(1). Binding famoxadone decreased this rate constant to 1,480 s(-1), consistent with a decrease in mobility of the ISP. Reverse electron transfer from cyt c(1) to 2Fe-2S was found to be biphasic in bovine cyt bc(1) with rate constants of 90,000 and 7,300 s(-1). In the presence of famoxadone, reverse electron transfer was monophasic with a rate constant of 1,420 s(-1). It appears that the rate constants for the release of the oxidized and reduced ISP from the b conformation are the same in the presence of famoxadone. The effects of famoxadone binding on electron transfer were also studied in a series of Rhodobacter sphaeroides cyt bc(1) mutants involving residues at the interface between the Rieske protein and cyt c(1) and/or cyt b.

Full Text

Duke Authors

Cited Authors

  • Xiao, K; Engstrom, G; Rajagukguk, S; Yu, C-A; Yu, L; Durham, B; Millett, F

Published Date

  • March 28, 2003

Published In

Volume / Issue

  • 278 / 13

Start / End Page

  • 11419 - 11426

PubMed ID

  • 12525495

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.M211620200


  • eng

Conference Location

  • United States