Polland, Hans-Joachim and Franz, M. A. and Zinth, Wolfgang and Kaiser, Wolfgang and Oesterhelt, Dieter
Energy transfer from retinal to amino acids — a time-resolved study of the ultraviolet emission of bacteriorhodopsin.
In: Biochimica et Biophysica Acta (BBA) - Bioenergetics, No. 851: pp. 407-415
Two-step excitation of retinal in bacteriorhodopsin by visible light is followed by an energy transfer to amino acids that is seen as fluorescent emission around 350 nm. The fluorescence spectrum obtained after two-step excitation (2 × 527 nm) differs from the fluorescence spectrum obtained after one-step ultraviolet excitation (263.5 nm) by a strongly quenched emission with a fluorescence lifetime of 10 ± 5 ps and a smaller spectral width. The two-step absorption process presumably selects tryptophan residues which strongly couple to the retinal chromophore.