A resonance Raman molecular probe was used to measure the surface potential of membrane fragments which contain bacteriorhodopsin. It is shown that the surface potential of the native membranes is identical to that of bleached bacteriorhodopsin. It is therefore concluded that the secondary interactions between the retinal chromophore and the protein, which are known to exist, do not have a long-range effect on the exposure of the bacteriorhodopsin at the membrane's surface.
Bibliographical noteFunding Information:
We wish to thank Professor A.S. Waggoner of Carnegie-Mellon University for a gift of the dye WW-638 and its analogs. This research was supported by a grant from the US-Israel Binational Science Foundation, Jerusalem.
- Chromophore-protein interaction
- Membrane surface potential
- Molecular dye probe
- Purple membrane
- Resonance Raman spectroscopy