Journal ArticleDOI
Resonance Raman studies of the purple membrane
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TLDR
The individual resonance Raman spectra of the PM568 and M412 forms of light-adapted purple membrane from Halobacterium halobium have been measured and indicate that the retinal chromophore is linked to the purple membrane protein via a protonated and unprotonated Schiff base.Abstract:
The individual resonance Raman spectra of the PM568 and M412 forms of light-adapted purple membrane from Halobacterium halobium have been measured using the newly developed flow technique. For comparison purposes, the Raman spectra of the model chromophores, all-trans- and 13-cis retinal n-butylamine, both as protonated and unprotonated Schiff bases, have also been obtained. In agreement with previous work, the Raman data indicate that the retinal chromophore is linked to the purple membrane protein via a protonated. Schiff base in the case of the PM568 and an unprotonated Schiff base for the M412 form. The basic mechanism for color regulation in both forms appears to be electron delocalization. The spectral features of the two forms are different from each other and different from the model compound spectra.read more
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Bacteriorhodopsin and the purple membrane of halobacteria
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Closing in on bacteriorhodopsin: progress in understanding the molecule.
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Proteorhodopsin is a light-driven proton pump with variable vectoriality.
Thomas Friedrich,Sven Geibel,Rolf Kalmbach,Igor Chizhov,Kenichi Ataka,Joachim Heberle,Martin Engelhard,Ernst Bamberg +7 more
TL;DR: The results show that proteorhodopsin is a light-driven proton pump with characteristics similar to those of BR at alkaline pH, however, at acidic pH, the direction of proton pumping is inverted.