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The role of the `Rieske' iron sulfur protein in the hydroquinone oxidation (Q P ) site of the cytochrome bc 1 complex
Author(s) -
Link Thomas A
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(97)00772-2
Subject(s) - semiquinone , hydroquinone , chemistry , quinone , cytochrome , stereochemistry , iron–sulfur cluster , cytochrome c , photochemistry , cluster (spacecraft) , crystallography , biochemistry , mitochondrion , enzyme , computer science , programming language
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 (Q P ) 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 Q P 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.