X-ray photoelectron spectroscopy has been applied for 13-(trifluoromethyl)-bacteriorhodopsin in order to study the electrostatic environment of retinylidene moiety in bacteriorhodopsin. It has been found that the F Is binding energy of the pigment is about 3.4 eV smaller than that of free 13-(trifluoromethyl)retinal. This is the first and direct experimental detection of an external negative charge characterizing the optical properties of bacteriorhodopsin. The numerical interpretation of the chemical shift suggests that the negative charge is situated about 3 A distant from the C13-methyl group of a retinal molecule.
ASJC Scopus subject areas
- Physics and Astronomy(all)