The trans-cis isomerization reaction dynamics in sensory rhodopsin II by femtosecond time-resolved midinfrared spectroscopy: chromophore and protein dynamics.
Transient infrared (IR) vibrational spectroscopy at subpicosecond time resolution on sensory rhodopsin II from Natronomonas pharaonis, NpSRII, has been performed for the first time. The experiments yield three time constants for the description of the primary photoinduced reaction dynamics, i.e. 0.5, 3.7-4.4, and 11 ps. The data are consistent with a sequential reaction scheme, with the isomerization taking place within 0.5 ps, succeeded by an electronic ground state relaxation. The 11 ps component, observed at 1550 and 1530 cm(-1), is attributed to dynamics of protein vibrational bands, possibly amide II bands of the protein backbone, perturbed by the ultrafast retinal photoisomerization. Similar observations, yet not as strongly expressed, have been made earlier in bacteriorhodopsin and halorhodopsin.
Fachbereich Physik, TU Kaiserslautern, E. Schrödinger Strasse, Geb. 46, D-67663 Kaiserslautern, Germany. diller@physik.uni-kl.de
Rolf
R
Diller
Ruth
R
Jakober
Christian
C
Schumann
Frank
F
Peters
Johann P
JP
Klare
Martin
M
Engelhard
D001436:Bacteriorhodopsins / Q000737:chemistry*; D007700:Kinetics; D019633:Natronobacterium / Q000737:chemistry; D020283:Photoreceptors, Microbial / Q000737:chemistry; D025603:Sensory Rhodopsins / Q000737:chemistry*; D013055:Spectrophotometry, Infrared / Q000379:methods*; D013237:Stereoisomerism; D014732:Vibration
D020283:Photoreceptors, Microbial; D025603:Sensory Rhodopsins; D001436:Bacteriorhodopsins