Excited-state lifetimes of far-infrared collective modes in proteins.
Vibrational excitations of low frequency collective modes are essential for functionally important conformational transitions in proteins. Here we report the first direct measurement on the lifetime of vibrational excitations of the collective modes at 87 microm (115 cm(-1)) in bacteriorhodopsin, a transmembrane protein. The data show that these modes have extremely long lifetime of vibrational excitations, over 500 ps, accommodating 1500 vibrations. We suggest that there is a connection between this relatively slow anharmonic relaxation rate of approximately 10(9) sec(-1) and the similar observed rate of conformational transitions in proteins, which require multilevel vibrational excitations.
Xie
Aihua
A
Department of Physics, Oklahoma State University, Stillwater, OK 74078, USA.
van der Meer
Alexander F G
AF
Austin
Robert H
RH
D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D013055:Spectrophotometry, Infrared / Q000379:methods
D011506:Proteins