Kinetics of the N intermediate and the two pathways of recovery of the ground-state of bacteriorhodopsin.
Absorption kinetic measurements at alkaline pH, in which bacteriorhodopsin (BR) is pre-excited by another flash, indicate that a part of the recovery of the BR ground-state is faster than the decay of the N intermediate of the photocycle. This fact proves the existence of a parallel pathway in the late part of the BR photocycle (the decay of Ms into BR), which does not include the N intermediate. We demonstrate that the decay of the Mf intermediate does not lead to any direct recovery of the BR ground-state, and that excitation of N does not form an M-like intermediate. Mf decays directly into the N intermediate, and photoexcitation of N leads to the formation of a red-shifted form, O*. The kinetics of this red-shifted intermediate are also presented.
Tokaji
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Z
Institute of Biophysics, Biological Research Center, Szeged, Hungary.
Dancsházy
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Z
D001436:Bacteriorhodopsins / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008962:Models, Theoretical; D010782:Photolysis; D013053:Spectrophotometry
D001436:Bacteriorhodopsins