FEBS letters, 2007-04, Vol.581 (8), p.1535-1541
2007
Details
- Autor(en) / Beteiligte
- Titel
- Intermonomer electron transfer in the bc 1 complex dimer is controlled by the energized state and by impaired electron transfer between low and high potential hemes
- Ist Teil von
- FEBS letters, 2007-04, Vol.581 (8), p.1535-1541
- Ort / Verlag
- Elsevier B.V
- Erscheinungsjahr
- 2007
- Link zum Volltext
- Quelle
- Alma/SFX Local Collection
- Beschreibungen/Notizen
- The cytochrome bc 1 complex (commonly called Complex III) is the central enzyme of respiratory and photosynthetic electron transfer chains. X-ray structures have revealed the bc 1 complex to be a dimer, and show that the distance between low potential ( b L) and high potential ( b H) hemes, is similar to the distance between low potential hemes in different monomers. This suggests that electron transfer between monomers should occur at the level of the b L hemes. Here, we show that although the rate constant for b L → b L electron transfer is substantial, it is slow compared to the forward rate from b L to b H, and the intermonomer transfer only occurs after equilibration within the first monomer. The effective rate of intermonomer transfer is about 2-orders of magnitude slower than the direct intermonomer electron transfer.
- Sprache
- Englisch
- Identifikatoren
- ISSN: 0014-5793eISSN: 1873-3468DOI: 10.1016/j.febslet.2007.03.037Titel-ID: cdi_crossref_primary_10_1016_j_febslet_2007_03_037
- Format
- –
- Schlagworte
- apparent rate constant of electron transfer between monomers, apparent time of electron transfer between monomers, which takes into account the equilibration within the initial monomer, b L and b H, bc 1 complex, coenzyme Q (ubiquinone), Coenzyme Q-10, Complex III, cyt, Cyt bc 1, Cyt bc1, cytochrome, difference of reorganization energies for the reactions b L ↔ b H and b L ↔ b L, dihydroquinone (ubiquinol), Dimer, E h, E m, edge-to-edge distance, edge-to-edge distance between b L and b H hemes, Electron transfer, intrinsic time of electron transfer between b L hemes, ISP, k app, K b L b H, K b L b H 0, k b L b L, K bHQ, low- and high-potential hemes of cytochrome b, respectively, MET, midpoint redox potential, Monomer, monomer–monomer electron transfer, QH2, Qi site (Qo site), quinone reducing (quinol oxidizing) site of bc 1 complex, r b L b H, r b L b L, redox potential of the medium, Rhodobacter, Rieske iron–sulfur protein, semiquinone, Superoxide, the absolute temperature, the coefficient in Eq. , equal to either 4.2, or 3.1, the equilibrium constant of electron transfer between b L and b H hemes, the equilibrium constant of electron transfer between b L and b H hemes at zero transmembrane potential, the equilibrium constant of electron transfer from cyt b H to Qi, the Faraday constant, the fraction of Δψ applied between b H and b L, the gas constant, the intrinsic rate constant of electron transfer between b L and b H hemes in the same monomer, the intrinsic rate constant of electron transfer between b L hemes, the reorganization energy in eV, the standard reaction free energy in eV, transmembrane electric potential, ubiquinol:cytochrome c oxidoreductase, Ubiquinone, ΔG, τ app = 1/k app, τ b L b L