The role of the conserved tryptophan272 of the Paracoccus denitrificans cytochrome c oxidase in proton pumping.
The catalytic mechanism of heme-copper oxidases - electron transfer coupled to proton pumping - is not yet fully understood. Single turnover experiments in which fully reduced cytochrome aa(3) from Paracoccus denitrificans reacts with O(2) using the microsecond freeze-hyperquenching sampling technique enabled trapping of transient catalytic intermediates and analysis by low temperature UV-Visible, X-band and Q-band EPR spectroscopy. Our recent findings (Wiertz et al. (2007) J. Biol. Chem. 282, 31580-31591), which show that the strictly conserved W272 is a redox active residue are reviewed here. The W272 forms a tryptophan neutral radical in the transition F-->F(W)-->O(H) in which the novel intermediate F(W) harbors the tryptophan radical. The potential role of W272 in proton pumping is highlighted.
de Vries
Simon
S
Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC, Delft, The Netherlands. s.devries@tudelft.nl
D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D017124:Conserved Sequence; D004578:Electron Spin Resonance Spectroscopy; D003576:Electron Transport Complex IV / Q000737:chemistry* / Q000378:metabolism*; D007700:Kinetics; D008954:Models, Biological; D008958:Models, Molecular; D010231:Paracoccus denitrificans / Q000201:enzymology*; D011487:Protein Conformation; D017494:Proton Pumps / Q000737:chemistry* / Q000378:metabolism*; D014364:Tryptophan
D001426:Bacterial Proteins; D017494:Proton Pumps; D014364:Tryptophan; D003576:Electron Transport Complex IV