The bleaching of purple membranes does not change their surface potential

AbstractA 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