Femtosecond Spectroscopy of Bacteriorhodopsin Excited State Dynamics

Abstract

Time-resolved ( 100 fs) spectroscopy of the transformation of light-adapted bacteriorhodopsin (bR570) into bathobacteriorhodopsin (K610) showed that, based on the kinetics of the spectral changes, the ground state of K610 forms directly from the excited state of bR570, and this occurs within 1 ps at physiol. temp. The rate of formation of the K610 may be affected by deuteration at room temp., as shown by the effects of D2O on the time const. for decay of bR570 transmittance at 570 nm. The power of femtosecond spectroscopy in studying bacteriorhodopsin photochem. is demonstrated by these expts.