The role of the `Rieske' iron sulfur protein in the hydroquinone oxidation (QP) site of the cytochrome bc1 complex
- 28 July 1997
- journal article
- review article
- Published by Wiley in FEBS Letters
- Vol. 412 (2) , 257-264
- https://doi.org/10.1016/s0014-5793(97)00772-2
Abstract
The essential reaction in the widely accepted protonmotive Q-cycle mechanism of the bc 1 complex is the bifurcation of the electron flow during hydroquinone oxidation at the hydroquinone oxidation (QP) site formed by the `Rieske' iron sulfur protein and by the heme b L domain of cytochrome b. The `Rieske' [2Fe-2S] cluster has a unique structure containing two exposed histidine ligands, which are the binding site for quinones. The affinity of the `Rieske' cluster for quinones increases several orders of magnitude upon reduction; this will stabilize semiquinone at the QP site. Based on this affinity change, a reaction scheme is presented which can explain the bifurcation of the electron flow without invoking highly unstable semiquinone species.Keywords
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