UV fluorescence spectroscopic behaviors in the picosecond time region for purple membrane were investigated by a method of a two-dimensional synchroscan streak camera with a mode-locked and internally frequency-doubled CW ring dye laser. The UV fluorescence from the tryptophans in bacteriorhodopsin shows the exponentially decaying profile of two components (about 130 and 650 ps). The peaks of the emission bands of the first and slow components are around 325 and 340 nm., respectively. These results show that the circumstance surrounding eight tryptophans in bacteriorhodopsin is at least sorted to the polar and nonpolar in ones. Furthermore, by applying Förster theory of energy transfer to the results, it is determined that the mean distance between the tryptophan indicating the fast fluorescence decay and the chromophore and that for the slow decay are 31 and 26 A. These support the following deduction from another analysis of stereographical conformation of bacteriorhodopsin; the membrane-buried protein has the “INSIDE OUT” conformation.
