Mapping the ultrafast vibrational dynamics of all-transand 13-cisretinal isomerization in Anabaena Sensory Rhodopsin

Abstract

Photoinduced vibrational dynamics between two stereoisomers of the retinal chromophore bound inside the same protein cavity has been explored.

Point Mutation of Anabaena Sensory Rhodopsin Enhances Ground-State Hydrogen Out-of-Plane Wag Raman Activity

“…This trend of relative weaker low-frequency modes when compared to high-frequency modes in nonresonant experiments is consistently observed at other detection wavelengths for all samples (see Figures S6 and S7). The same trend was also observed recently in nonresonant Raman experiments for ASR as well as for bacteriorhodopsin . Thus, it corroborates the assignment of the low-frequency modes between 100 and 400 cm –1 mainly to the excited state (see also section IV in the Supporting Information).…”

“…Our recent experimental study on structural dynamics of the RPSB in WT ASR has not only shown experimental evidence in favor of the theoretical prediction of the barrier but also depicted a significantly more predistorted ground-state structure for the 13C-isomer compared to the AT-isomer. Similar predistortion of ground-state retinal structure has been frequently claimed to accelerate the isomerization rate for 11- cis isomer in visual rhodopsin − and 13- cis isomer in bacteriorhodopsin (BR). , Even in the gas phase, where no protein-assisted electrostatic interactions are present, RPSB exhibits a barrierless sub-100 fs isomerization kinetics when it adopts a twisted ground-state geometry .…”

Vibrational Coherence Spectroscopy Identifies Ultrafast Branching in an Iron(II) Sensitizer

“…The experimental setups used for TA and (P-)IVS have been described elsewhere. 30 In the TA measurement, the pump pulse energy was set to 100 nJ. In (pump-)IVS measurements, the actinic pump pulse energy was set to 300 nJ, the push pulse energy to 100 nJ, and the probe pulse energy to 20 nJ with spot diameters of 100, 80, and 60 μm, respectively.…”

“…The optical densities of all samples were between 0.4 and 0.5 OD at their ground state absorption maximum in a 0.5 mm flow-cell cuvette. The experimental setups used for TA and (P-)­IVS have been described elsewhere . In the TA measurement, the pump pulse energy was set to 100 nJ.…”

Raman Scattering: From Structural Biology to Medical Applications

“…Another sensory rhodopsin from Anabaena (ASR) has 13C (13-cis, 15-syn) and AT (all-trans) isomers that have structural and dynamical differences in the isomerization. In the recent study, the Raman measurements showed that the longer dynamics that were observed for AT ASR may result both from a barrier in the excited state and the lack of a pre-distortion (compared to 13C isomer) in the ground state [320]. The increase of ground-state C14−HOOP Raman activity of AT and 13C-isomers caused by point mutation showed that localized change in electrostatic interaction mutation might induce a subtle distortion of retinal geometry, which might lead to an accelerated isomerization kinetics [321].…”