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Protonmotive pathways and mechanisms in the cytochrome bc 1 complex
Author(s) -
Hunte Carola,
Palsdottir Hildur,
Trumpower Bernard L
Publication year - 2003
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(03)00391-0
Subject(s) - chemistry , cytochrome c1 , ubiquinol , coenzyme q – cytochrome c reductase , redox , quinone , electron transfer , cytochrome , electron transport chain , cytochrome c , cytochrome b6f complex , proton , cytochrome b , stereochemistry , photochemistry , crystallography , mitochondrion , biochemistry , inorganic chemistry , enzyme , physics , quantum mechanics , mitochondrial dna , gene
The cytochrome bc 1 complex catalyzes electron transfer from ubiquinol to cytochrome c by a protonmotive Q cycle mechanism in which electron transfer is linked to proton translocation across the inner mitochondrial membrane. In the Q cycle mechanism proton translocation is the net result of topographically segregated reduction of quinone and reoxidation of quinol on opposite sides of the membrane, with protons being carried across the membrane as hydrogens on the quinol. The linkage of proton chemistry to electron transfer during quinol oxidation and quinone reduction requires pathways for moving protons to and from the aqueous phase and the hydrophobic environment in which the quinol and quinone redox reactions occur. Crystal structures of the mitochondrial cytochrome bc 1 complexes in various conformations allow insight into possible proton conduction pathways. In this review we discuss pathways for proton conduction linked to ubiquinone redox reactions with particular reference to recently determined structures of the yeast bc 1 complex.