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The photochemical cycle of bacteriorhodopsinThe reaction cycle of bacteriorhodopsin in the purple membrane isolated from Halobacterium halobium has been studied by optical absorption spectroscopy using low-temperature and flash kinetic techniques. After absorption of light, bacteriorhodopsin passes through at least five distinct intermediates. The temperature and pH dependence of the absorbance changes suggests that branch points and/or reversible steps exist in this cycle. Flash spectroscopy in the presence of a pH-indicating dye shows that the transient release of a proton accompanies the photoreaction cycle. The proton release occurs from the exterior and the uptake is on the cytoplasmic side of the membrane, as required by the function of bacteriorhodopsin as a light-driven proton pump. Proton translocating steps connecting release and uptake are indicated by deuterium isotope effects on the kinetics of the cycle. The rapid decay of a light-induced linear dichroism shows that a chromophore orientation change occurs during the reaction cycle.
Document ID
19770056054
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Lozier, R. H.
(NASA Ames Research Center Moffett Field, Calif., United States)
Niederberger, W.
(California, University San Francisco, Calif., United States)
Date Acquired
August 9, 2013
Publication Date
May 1, 1977
Subject Category
Life Sciences (General)
Accession Number
77A38906
Funding Number(s)
CONTRACT_GRANT: NSG-7151
CONTRACT_GRANT: NIH-HL-06285
Distribution Limits
Public
Copyright
Other

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