Picosecond-Resonance Coherent Anti-Stokes Raman Scattering in Biophysics: Power Dependence in the Bacteriorhodopsin Photocycle

Atkinson, Gordon; Popp, Andreas; Ujj, Laszlo

doi:10.1007/978-3-642-85060-8_37

Cited by 3 publications

(1 citation statement)

References 7 publications

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“…Differences in probe laser power may underlie the observed frequency shift. The influence of the probe power on the shape and position of bands also has been demonstrated for the ethylenic modes in PTR/CARS data (Atkinson et al, 1994).…”

Section: Comparisons With Previous Vibrational Datamentioning

confidence: 80%

Nanosecond retinal structure changes in K-590 during the room-temperature bacteriorhodopsin photocycle: picosecond time-resolved coherent anti-stokes Raman spectroscopy

Weidlich

Ujj

Jäger

et al. 1997

Biophysical Journal

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Time-resolved vibrational spectra are used to elucidate the structural changes in the retinal chromophore within the K-590 intermediate that precedes the formation of the L-550 intermediate in the room-temperature (RT) bacteriorhodopsin (BR) photocycle. Measured by picosecond time-resolved coherent anti-Stokes Raman scattering (PTR/CARS), these vibrational data are recorded within the 750 cm-1 to 1720 cm-1 spectral region and with time delays of 50-260 ns after the RT/BR photocycle is optically initiated by pulsed (< 3 ps, 1.75 nJ) excitation. Although K-590 remains structurally unchanged throughout the 50-ps to 1-ns time interval, distinct structural changes do appear over the 1-ns to 260-ns period. Specifically, comparisons of the 50-ps PTR/CARS spectra with those recorded with time delays of 1 ns to 260 ns reveal 1) three types of changes in the hydrogen-out-of-plane (HOOP) region: the appearance of a strong, new feature at 984 cm-1; intensity decreases for the bands at 957 cm-1, 952 cm-1, and 939 cm-1; and small changes intensity and/or frequency of bands at 855 cm-1 and 805 cm-1; and 2) two types of changes in the C-C stretching region: the intensity increase in the band at 1196 cm-1 and small intensity changes and/or frequency shifts for bands at 1300 cm-1 and 1362 cm-1. No changes are observed in the C = C stretching region, and no bands assignable to the Schiff base stretching mode (C = NH+) mode are found in any of the PTR/CARS spectra assignable to K-590. These PTR/CARS data are used, together with vibrational mode assignments derived from previous work, to characterize the retinal structural changes in K-590 as it evolves from its 3.5-ps formation (ps/K-590) through the nanosecond time regime (ns/K-590) that precedes the formation of L-550. The PTR/CARS data suggest that changes in the torsional modes near the C14-C15 = N bonds are directly associated with the appearance of ns/K-590, and perhaps with the KL intermediate proposed in earlier studies. These vibrational data can be primarily interpreted in terms of the degree of twisting of the C14-C15 retinal bond. Such twisting may be accompanied by changes in the adjacent protein. Other smaller, but nonetheless clear, spectral changes indicate that alterations along the retinal polyene chain also occur. The changes in the retinal structure are preliminary to the deprotonation of the Schiff base nitrogen during the formation of M-412. The time constant for the ps/ns K-590 transformation is estimated from the amplitude change of four vibrational bands in the HOOP region to be 40-70 ns.

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Section: Comparisons With Previous Vibrational Datamentioning

confidence: 80%

Nanosecond retinal structure changes in K-590 during the room-temperature bacteriorhodopsin photocycle: picosecond time-resolved coherent anti-stokes Raman spectroscopy

Weidlich

Ujj

Jäger

et al. 1997

Biophysical Journal

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Application of Raman Spectroscopy to Retinal Proteins

Althaus

Eisfeld

Lohrmann

et al. 1995

Israel Journal of Chemistry

127

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Raman spectroscopic studies on photoreactive retinal proteins are comprehensively described, including the basic physics of Raman scattering and illustrative examples of the types of information on the structure and function of the retinal chromophoreand its environment which can be obtained from the vibrational Raman spectra. In addition, practical advice and recipes are given which should enable the reader to plan and eventually perform a Raman experiment in a photolabile retinal protein. A dominant role is played by the resonance Raman (RR) experiment with visible laser excitation which selelctively probes the retinal chromophore. Much discussion is devoted to bacteriorhodopsin (bR) and its photocycle as a paradigm for a light-inducedreaction of a retinal protein. Various time-resolved techniques are described to study the temporal evolution of the bR chromophore by probing RR spectra of intermediatestates. VibrationalRaman spectra are interpreted in terms of structure and structural changes of the chromophore. RR spectroscopic studies on halorhodopsin, sensory rhodopsin, and visual pigments are reported, as well as on modifiedproteins in which retinal analoguesare incorporated,and on sitespecific mutants. Results of ultraviolet RR experiments which selectively probe the aromatic side chains in the protein backbone are reported. In addition, a promising new technique of near-infrared Raman excitation is discussed. Finally, application of coherent anti-Stokes Raman spectroscopy (CARS) to retinal proteins is reported.

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Vibrational Spectrum of K-590 Containing¹³C_14,15Retinal: Picosecond Time-Resolved Coherent Anti-Stokes Raman Spectroscopy of the Room Temperature Bacteriorhodopsin Photocycle

Jäger¹,

Ujj²,

Atkinson³

et al. 1996

J. Phys. Chem.

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The C-C stretching vibrations (1100-1400 cm -1 ) of the K-590 intermediate (containing a 13 C 14,15 retinal), formed during the room-temperature (RT) bacteriorhodopsin (BR) photocycle, are measured using picosecond time-resolved coherent anti-Stokes Raman scattering (PTR/CARS). Although time-resolved resonance Raman data have been published previously for intermediates in the room-temperature BR photocycle, these PTR/ CARS data are the first time-resolved vibrational spectra from a picosecond BR intermediate at RT containing an isotopically-labeled ( 13 C) retinal. The C 14 and C 15 positions are selected for isotopic labeling because motions around the C 13 dC 14 and C 14 -C 15 bonds are thought to underlie the structural transformation from BR-570 to K-590 and, therefore, the energy storage and transduction mechanism in the RT/BR photocycle. These PTR/CARS data are recorded 50 ps after the BR photocycle is initiated with 570-nm (5 ps, fwhm) excitation and are fit to within <1 cm -1 via third-order nonlinear susceptibility (χ (3) ) relationships. Comparisons of these PTR/CARS data at RT with the results from earlier resonance Raman (RR) studies of K-590 at low temperature (LT) reveal new temperature effects. Specifically, three CARS bands (1197, 1184, and 1167 cm -1 ) are observed from 13 C 14,15 K-590 in H 2 O samples via PTR/CARS at RT, while only two bands (1189 and 1170 cm -1 ) are found in LT/RR measurements from 13 C 14,15 K-625. Analogous temperature-dependent differences are found in data measured from 13 C 14,15 K-590 in D 2 O samples. Independently, PTR/CARS data at RT demonstrate that deuteration of the Schiff-base nitrogen causes major changes in the fingerprint region: the 1197-cm -1 band decreases to 1193 cm -1 while diminishing in intensity by half and a new band appears at 1206 cm -1 . No such deuterium effect is observed in the LT/RR data from 13 C 14,15 K-590. The previously unrecognized sensitivity of fingerprint bands to deuteration of the Schiff-base nitrogen suggests that the C-C stretching modes are highly mixed with each other and coupled to the N-H(D) retinal rocking mode. Although the temperature and Schiff-base deuteration effects reported here had not been previously identified in LT vibrational data from K-625, an analysis of the RT/CARS data continues to support the 13-cis, 14-trans retinal structure in K-590 proposed from LT results.

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Picosecond-Resonance Coherent Anti-Stokes Raman Scattering in Biophysics: Power Dependence in the Bacteriorhodopsin Photocycle

Cited by 3 publications

References 7 publications

Nanosecond retinal structure changes in K-590 during the room-temperature bacteriorhodopsin photocycle: picosecond time-resolved coherent anti-stokes Raman spectroscopy

Nanosecond retinal structure changes in K-590 during the room-temperature bacteriorhodopsin photocycle: picosecond time-resolved coherent anti-stokes Raman spectroscopy

Application of Raman Spectroscopy to Retinal Proteins

Vibrational Spectrum of K-590 Containing¹³C_14,15Retinal: Picosecond Time-Resolved Coherent Anti-Stokes Raman Spectroscopy of the Room Temperature Bacteriorhodopsin Photocycle

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Picosecond-Resonance Coherent Anti-Stokes Raman Scattering in Biophysics: Power Dependence in the Bacteriorhodopsin Photocycle

Cited by 3 publications

References 7 publications

Nanosecond retinal structure changes in K-590 during the room-temperature bacteriorhodopsin photocycle: picosecond time-resolved coherent anti-stokes Raman spectroscopy

Nanosecond retinal structure changes in K-590 during the room-temperature bacteriorhodopsin photocycle: picosecond time-resolved coherent anti-stokes Raman spectroscopy

Application of Raman Spectroscopy to Retinal Proteins

Vibrational Spectrum of K-590 Containing13C14,15Retinal: Picosecond Time-Resolved Coherent Anti-Stokes Raman Spectroscopy of the Room Temperature Bacteriorhodopsin Photocycle

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Vibrational Spectrum of K-590 Containing¹³C_14,15Retinal: Picosecond Time-Resolved Coherent Anti-Stokes Raman Spectroscopy of the Room Temperature Bacteriorhodopsin Photocycle