title: A perspective on Q-cycles.
abstract: An examination is made of both the Q-cycle and b-cycle formulations of electron transfer and energy conservation in the cytochrome bc1 complex. A working hypothesis for the complex is presented, based upon the Q-cycle notion of vectorial reaction sites, but incorporating the b-cycle feature of semiquinone movement between these sites.
mesh_terms: D016227:Benzoquinones; D002736:Chloroplasts / Q000378:metabolism; D003573:Cytochrome b Group / Q000378:metabolism*; D004579:Electron Transport; D007700:Kinetics; D008956:Models, Chemical; D011522:Protons; D011809:Quinones / Q000378:metabolism*
chemical_list: D016227:Benzoquinones; D003573:Cytochrome b Group; D011522:Protons; D011809:Quinones; C004532:quinone