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.
Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC, Delft, The Netherlands. s.devries@tudelft.nl
Simon
S
de Vries
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