A cooperative model for protonmotive heme-copper oxidases. The role of heme a in the proton pump of cytochrome c oxidase.
Oxido-reductions of metal centers in cytochrome c oxidase are linked to pK shifts of acidic groups in the enzyme (redox Bohr effects). The linkage at heme a results in proton uptake from the inner space upon reduction and proton release in the external space upon oxidation of the metal. The relationship of this process to the features of the proton pump in cytochrome c oxidase and its atomic structure revealed by X-ray crystallography to 2.8-2.3 A resolution is examined. A mechanism for the proton pump of cytochrome c oxidase, based on cooperative coupling at heme a, is proposed.
Papa
S
S
Institute of Medical Biochemistry and Chemistry, University of Bari, Policlinico, Italy. papabchm@cimedoc.uniba.it
Capitanio
N
N
Villani
G
G
D000595:Amino Acid Sequence; D001412:Bacillus subtilis; D018360:Crystallography, X-Ray; D003576:Electron Transport Complex IV / Q000737:chemistry* / Q000502:physiology; D004926:Escherichia coli; D006418:Heme / Q000031:analogs & derivatives* / Q000737:chemistry / Q000502:physiology; D006420:Hemeproteins / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017494:Proton Pumps / Q000737:chemistry* / Q000502:physiology; D017386:Sequence Homology, Amino Acid
D006420:Hemeproteins; D017494:Proton Pumps; C027728:heme a; D006418:Heme; D003576:Electron Transport Complex IV