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. 1987 Oct;52(4):617–623. doi: 10.1016/S0006-3495(87)83252-6

The Pink Membrane

The Stable Photoproduct of Deionized Purple Membrane

Chung-Ho Chang, Su-Yi Liu, Roy Jonas, Rajni Govindjee
PMCID: PMC1330053  PMID: 19431706

Abstract

When cations are removed from the purple membrane of Halobacterium halobium it turns blue (λmax = 603 nm); continuous irradiation with intense red light (λ's ≥ 630 nm) converts this deionized blue membrane into a pink membrane (λmax ≈ 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.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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