The pink membrane: the stable photoproduct of deionized purple membrane

When cations are removed from the purple membrane of Halobacterium halobium it turns blue (lambda(max) = 603 nm); continuous irradiation with intense red light (lambda's >/= 630 nm) converts this deionized blue membrane into a pink membrane (lambda(max) approximately 491 nm). The rate and ex...

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Bibliographic Details
Published in:Biophysical journal 1987-10, Vol.52 (4), p.617-623
Main Authors: CHUNG-HO CHANG, SU-YI LIU, JONAS, R, RAJNI GOVINDJEE
Format: Article
Language:English
Subjects:
Biological and medical sciences
Cell structures and functions
Chloroplast, photosynthetic membrane and photosynthesis
Fundamental and applied biological sciences. Psychology
Molecular and cellular biology
purple membranes
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Summary:When cations are removed from the purple membrane of Halobacterium halobium it turns blue (lambda(max) = 603 nm); continuous irradiation with intense red light (lambda's >/= 630 nm) converts this deionized blue membrane into a pink membrane (lambda(max) approximately 491 nm). The rate and extent of the transformation from the blue to the pink membrane is facilitated by the removal of the last twenty COOH-terminal amino acids of bacteriorhodopsin. While the chromophore of the blue membrane is a 32:68 mixture of the 13-cis and all-trans isomers of retinal, the chromophore of the pink membrane is 9-cis rectinal. The quantum efficiency of the pink to blue membrane photoconversion is relatively high compared with that of the blue to pink membrane photoconversion. Proton release is observed when the pink membrane is converted to the blue form, and proton uptake occurs during the reverse transition. Unlike the blue membrane, the absorbance maximum of the pink membrane is only slightly affected by cation addition at low pH and ionic strength.
ISSN:0006-3495
1542-0086
DOI:10.1016/S0006-3495(87)83252-6