Thermal Effects in Resonance Raman Scattering: Analysis of the Raman Intensities of Rhodopsin and of the Time-Resolved Raman Scattering of Bacteriorhodopsin

Shreve, Andrew P.; Mathies, Richard A.

doi:10.1021/j100019a012

Cited by 76 publications

(111 citation statements)

References 15 publications

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“…In fact, the observed decreases in Raman cross-sections are also consistent with an increase in molecular temperature of Y268 and W265 (52), suggesting that these residues may act as acceptors for the excess energy as the all-trans chromophore undergoes intermolecular vibrational energy transfer. The greater intensity changes at 20 ps imply that W265 and Y268 continue to move away from the ring portion of the chromophore following isomerization.…”

Section: And I189 (51)supporting

confidence: 62%

Picosecond Dynamics of G-Protein Coupled Receptor Activation in Rhodopsin from Time-Resolved UV Resonance Raman Spectroscopy

2003

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The protein response to retinal chromophore isomerization in the visual pigment rhodopsin is studied using picosecond time-resolved UV resonance Raman spectroscopy. High signal-to-noise Raman spectra are obtained using a 1 kHz Ti:Sapphire laser apparatus that provides <3 ps visible (466 nm) pump and UV (233 nm) probe pulses. When there is no time delay between the pump and probe events, tryptophan modes W18, W16, and W3 exhibit decreased Raman scattering intensity. At longer pump-probe time delays of +5 and +20 ps, both tryptophan (W18, W16, W3, and W1) and tyrosine (Y1 + 2xY16a, Y7a, Y8a) peak intensities drop by up to 3%. These intensity changes are attributed to decreased hydrophobicity in the microenvironment near at least one tryptophan and one tyrosine residue that likely arise from weakened interaction with the β-ionone ring of the chromophore following cis-to-trans isomerization. Examination of the crystal structure suggests that W265 and Y268 are responsible for these signals. These UV Raman spectral changes are nearly identical to those observed for the rhodopsinto-Meta I transition, implying that impulsively driven protein motion by the isomerizing chromophore during the 200 fs primary transition drives key structural changes that lead to protein activation.Knowledge of the initial response of a protein to an activating agent or event is required to derive a mechanistic understanding of protein function. In the case of the visual pigment rhodopsin, absorption of a single visible photon by the antagonist 11-cis retinal chromophore results in the formation of a highly energetic activated all-trans photo-product (1). This stored energy is transduced into global protein conformational changes at the Meta I-Meta II stages that trigger the G-protein visual cascade (2). The mechanism by which the photoisomerization reaction induces protein conformational changes is not understood, largely due to the lack of high temporal resolution structural tools that can elucidate these early events. Here, we report the first structural study of the protein conformational changes associated with the primary photochemical event in vision using picosecond time-resolved UV resonance Raman vibrational spectroscopy.Vibrational structural studies of biomolecules have greatly advanced since the introduction of UV resonance Raman (UVRR) 1 spectroscopy (3-5). When the excitation wavelength is tuned between ∼195 and 260 nm, strong resonance Raman scattering from the peptide backbone and aromatic amino acids provides vibrational information on local protein structure and environmental changes. This technique has been used, for example, to study rhodopsin protein structure (6), protein folding (7, 8), and protein-ligand interactions (9, 10). In addition, time- † We dedicate this paper to the memory of Helena (Ilona) Anna Palings (1956Palings ( -2002. This work was supported by grants from the National Institutes of Health (EY-02051) and the National Science Foundation (CHE-98-01651 (6,27,28), there remains a lack of understa...

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Section: And I189 (51)supporting

confidence: 62%

Picosecond Dynamics of G-Protein Coupled Receptor Activation in Rhodopsin from Time-Resolved UV Resonance Raman Spectroscopy

2003

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“…In light of the weak electron-phonon coupling, this should be equivalent to a model including all 39 modes appearing in the Raman spectrum. 29 This model consists of 10 of the Raman modes, some of which represent the intensity of several nearby modes. For example, the 384 cm -1 mode represents five modes, that is, it carries an intensity (relative to the 94 cm -1 mode) of 0.70 + 0.67 + 0.12 + 0.53 + 0.23 ) 2.25, the combined intensity, respectively, of the 360, 384, 473, 546, and 583 cm -1 modes.…”

Section: Resultsmentioning

confidence: 99%

Near-Infrared Resonance Raman Spectra of Chlorosomes: Probing Nuclear Coupling in Electronic Energy Transfer

Cherepy

Holzwarth

et al. 1996

J. Phys. Chem.

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Resonance Raman spectra of chlorosomes, isolated from the green bacteria Chloroflexus aurantiacus and Chlorobium tepidum, have been obtained with excitation in their near-infrared (Q y ) absorption bands by using shifted-excitation Raman difference spectroscopy. Both spectra exhibit strong low-frequency (50-300 cm -1 ) modes, although these modes are relatively more intense in the Chloroflexus aurantiacus spectrum than in the Chlorobium tepidum spectrum. These intensity differences indicate that the low-frequency electronnuclear coupling is strongest in the Chloroflexus aurantiacus chlorosome. The Raman spectrum of the Chloroflexus aurantiacus chlorosome is independent of excitation wavelength, and the scattering intensity tracks the absorption band and relative Raman intensities. A model comprised of more than one transition having similar vibronic parameters most successfully reproduces the Chloroflexus aurantiacus Q y absorption band shape. The resonance Raman mode frequencies and intensities agree qualitatively with the power spectrum generated by Fourier transforming the oscillations seen in femtosecond stimulated emission measurements on both chlorosomes. The greater intensity of the low-frequency Raman modes observed for the Chloroflexus aurantiacus chlorosome is consistent with the increased amplitudes of the stimulated emission oscillations seen for that chlorosome. These data provide a more quantitative understanding of the vibronic properties of chlorosomes that can now be used to explore the possible role of vibrational coherence in energy transfer.

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“…47 The physiological function of bR in live bacteria is proton pumping to produce a chemical potential for ATP synthesis. This pump is optically triggered by transcis photoisomerization, which is closely related to cistrans photoisomerization of rhodopsin in the vision process 48 even though the reaction is in the opposite direction. Because of these interesting physiological and artificial functionalities, the primary process of bR has been extensively studied both theoretically 49,50 and experimentally.…”

Section: An Example Of Real-time Spectroscopymentioning

confidence: 99%

Development of Ultrafast Spectroscopy and Reaction Mechanisms Studied by the Observation of Ultrashort-Life Species and Transition States

Kobayashi

2013

Bulletin of the Chemical Society of Japan

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Thermal Effects in Resonance Raman Scattering: Analysis of the Raman Intensities of Rhodopsin and of the Time-Resolved Raman Scattering of Bacteriorhodopsin

Cited by 76 publications

References 15 publications

Picosecond Dynamics of G-Protein Coupled Receptor Activation in Rhodopsin from Time-Resolved UV Resonance Raman Spectroscopy

Picosecond Dynamics of G-Protein Coupled Receptor Activation in Rhodopsin from Time-Resolved UV Resonance Raman Spectroscopy

Near-Infrared Resonance Raman Spectra of Chlorosomes: Probing Nuclear Coupling in Electronic Energy Transfer

Development of Ultrafast Spectroscopy and Reaction Mechanisms Studied by the Observation of Ultrashort-Life Species and Transition States

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