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The proton pump of heme‐copper oxidases.
Author(s) -
Papa S.,
Capitanio N.,
Glaser P.,
Villani G.
Publication year - 1994
Publication title -
cell biology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 77
eISSN - 1095-8355
pISSN - 1065-6995
DOI - 10.1006/cbir.1994.1084
Subject(s) - heme a , cytochrome c oxidase , protein subunit , chemistry , heme , respiratory chain , cytochrome , electron transport complex iv , oxidase test , chemiosmosis , biochemistry , electron transfer , coupling (piping) , stereochemistry , biophysics , enzyme , photochemistry , atp synthase , biology , mechanical engineering , engineering , gene
Proton pumping heme‐copper oxidases represent the terminal, energy‐transfer enzymes of respiratory chains in prokaryotes and eukaryotes. The Cu B ‐heme a 3 (or heme o) binuclear center, associated with the largest subunit I of cytochrome c and quinol oxidases, is directly involved in the coupling between dioxygen reduction and proton pumping. The role of the other subunits is less clear. The following aspects will be covered in this paper:i) the efficiency of coupling in the mitochondrial aa 3 cytochrome c oxidase. In particular, the effect of respiratory rate and protonmotive force on the H + /e − stoichiometry and the role of subunit IV; ii) mutational analysis of the aa 3 quinol oxidase of Bacillus subtilis addressed to the role of subunit III, subunit IV and specific residues in subunit I; iii) possible models of the protonmotive catalytic cycle at the binuclear center. The observations available suggest that H + /e − coupling is based on the combination of protonmotive redox catalysis at the binuclear center and co‐operative proton transfer in the protein.