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A new intermediate in the photocycle of bacteriorhodopsin
Author(s) -
Dancshazy Zsolt,
Govindjee Rajni,
Nelson Burr,
Ebrey Thomas G.
Publication year - 1986
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(86)81081-x
Subject(s) - bacteriorhodopsin , absorbance , kinetics , chemistry , halobacteriaceae , wavelength , spectral line , photochemistry , analytical chemistry (journal) , materials science , physics , halobacterium salinarum , optoelectronics , chromatography , biochemistry , membrane , quantum mechanics , astronomy
With increasing pH (6.0 to 10.5) there is an increasing discrepancy between the recovery rate of bacteriorhodopsin after a flash and the decay rates of the key photointermediates, M fast and M slow , which is not predicted by any model of the photocycle. However, a very slowly decaying absorbance change at 350 nm has kinetics which match the very slow part of the recovery of bacteriorhodopsin, suggesting a new intermediate. The difference spectra of the bacteriorhodopsin photocycle measured at pH 10.5, obtained from fitting 3 exponentials to the flash‐induced absorbance changes in the 300–560 nm wavelength range, show maxima, at 410–420 nm corresponding to the 2 forms of M and at 350 nm corresponding to the new intermediate. We propose to call this new species R350.