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Kraack JP, Buckup T, Motzkus M. Evidence for the Two-State-Two-Mode model in retinal protonated Schiff-bases from pump degenerate four-wave-mixing experiments. Phys Chem Chem Phys 2012; 14:13979-88. [DOI: 10.1039/c2cp42248d] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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53
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Qiu X, Li X, Niu K, Lee SY. Inverse Raman bands in ultrafast Raman loss spectroscopy. J Chem Phys 2011; 135:164502. [DOI: 10.1063/1.3653940] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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54
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Sahoo SK, Umapathy S, Parker AW. Time-resolved resonance Raman spectroscopy: exploring reactive intermediates. APPLIED SPECTROSCOPY 2011; 65:1087-115. [PMID: 21986070 DOI: 10.1366/11-06406] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The study of reaction mechanisms involves systematic investigations of the correlation between structure, reactivity, and time. The challenge is to be able to observe the chemical changes undergone by reactants as they change into products via one or several intermediates such as electronic excited states (singlet and triplet), radicals, radical ions, carbocations, carbanions, carbenes, nitrenes, nitrinium ions, etc. The vast array of intermediates and timescales means there is no single "do-it-all" technique. The simultaneous advances in contemporary time-resolved Raman spectroscopic techniques and computational methods have done much towards visualizing molecular fingerprint snapshots of the reactive intermediates in the microsecond to femtosecond time domain. Raman spectroscopy and its sensitive counterpart resonance Raman spectroscopy have been well proven as means for determining molecular structure, chemical bonding, reactivity, and dynamics of short-lived intermediates in solution phase and are advantageous in comparison to commonly used time-resolved absorption and emission spectroscopy. Today time-resolved Raman spectroscopy is a mature technique; its development owes much to the advent of pulsed tunable lasers, highly efficient spectrometers, and high speed, highly sensitive multichannel detectors able to collect a complete spectrum. This review article will provide a brief chronological development of the experimental setup and demonstrate how experimentalists have conquered numerous challenges to obtain background-free (removing fluorescence), intense, and highly spectrally resolved Raman spectra in the nanosecond to microsecond (ns-μs) and picosecond (ps) time domains and, perhaps surprisingly, laid the foundations for new techniques such as spatially offset Raman spectroscopy.
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Affiliation(s)
- Sangram Keshari Sahoo
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore-560012, India
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55
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Roy S, Prasad M. Design of All-Optical Reconfigurable Logic Unit With Bacteriorhodopsin Protein Coated Microcavity Switches. IEEE Trans Nanobioscience 2011; 10:160-71. [DOI: 10.1109/tnb.2011.2163525] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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56
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Li X, Chung LW, Morokuma K. Photodynamics of All-trans Retinal Protonated Schiff Base in Bacteriorhodopsin and Methanol Solution. J Chem Theory Comput 2011; 7:2694-8. [DOI: 10.1021/ct200549z] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Xin Li
- Fukui Institute for Fundamental Chemistry, Kyoto University, Kyoto 606-8103, Japan
| | - Lung Wa Chung
- Fukui Institute for Fundamental Chemistry, Kyoto University, Kyoto 606-8103, Japan
| | - Keiji Morokuma
- Fukui Institute for Fundamental Chemistry, Kyoto University, Kyoto 606-8103, Japan
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Groma GI, Colonna A, Martin JL, Vos MH. Vibrational motions associated with primary processes in bacteriorhodopsin studied by coherent infrared emission spectroscopy. Biophys J 2011; 100:1578-86. [PMID: 21402041 DOI: 10.1016/j.bpj.2011.02.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 02/01/2011] [Accepted: 02/04/2011] [Indexed: 11/18/2022] Open
Abstract
The primary energetic processes driving the functional proton pump of bacteriorhodopsin take place in the form of complex molecular dynamic events after excitation of the retinal chromophore into the Franck-Condon state. These early events include a strong electronic polarization, skeletal stretching, and all-trans-to-13-cis isomerization upon formation of the J intermediate. The effectiveness of the photoreaction is ensured by a conical intersection between the electronic excited and ground states, providing highly nonadiabatic coupling to nuclear motions. Here, we study real-time vibrational coherences associated with these motions by analyzing light-induced infrared emission from oriented purple membranes in the 750-1400 cm(-)(1) region. The experimental technique applied is based on second-order femtosecond difference frequency generation on macroscopically ordered samples that also yield information on phase and direction of the underlying motions. Concerted use of several analysis methods resulted in the isolation and characterization of seven different vibrational modes, assigned as C-C stretches, out-of-plane methyl rocks, and hydrogen out-of-plane wags, whereas no in-plane H rock was found. Based on their lifetimes and several other criteria, we deduce that the majority of the observed modes take place on the potential energy surface of the excited electronic state. In particular, the direction sensitivity provides experimental evidence for large intermediate distortions of the retinal plane during the excited-state isomerization process.
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Affiliation(s)
- Géza I Groma
- Laboratory for Optical Biosciences, Ecole Polytechnique, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Palaiseau, France.
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58
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Kraack JP, Buckup T, Hampp N, Motzkus M. Ground- and Excited-State Vibrational Coherence Dynamics in Bacteriorhodopsin Probed With Degenerate Four-Wave-Mixing Experiments. Chemphyschem 2011; 12:1851-9. [DOI: 10.1002/cphc.201100032] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 05/24/2011] [Indexed: 11/06/2022]
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59
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Zhao B, Sun Z, Lee SY. Quantum theory of time-resolved femtosecond stimulated Raman spectroscopy: direct versus cascade processes and application to CDCl3. J Chem Phys 2011; 134:024307. [PMID: 21241099 DOI: 10.1063/1.3525100] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
We present a quantum mechanical wave packet treatment of time-resolved femtosecond stimulated Raman spectroscopy (FSRS), or two-dimensional (2D) FSRS, where a vibrational coherence is initiated with an impulsive Raman pump which is subsequently probed by FSRS. It complements the recent classical treatment by Mehlenbacher et al. [J. Chem. Phys. 131, 244512 (2009)]. In this 2D-FSRS, two processes can occur concurrently but with different intensities: a direct fifth-order process taking place on one molecule, and a cascade process comprising two third-order processes on two different molecules. The cascade process comprises a parallel and a sequential cascade. The theory is applied to the 2D-FSRS of CDCl(3) where calculations showed that: (a) the cascade process is stronger than the direct fifth-order process by one order of magnitude, (b) the sidebands assigned to C-Cl E and A(1) bends, observed on both sides of the Stokes C-D stretch frequency, are not due to anharmonic coupling between the C-D stretch and the C-Cl bends, but are instead due to the coherent anti-Stokes Raman spectroscopy (CARS) and coherent Stokes Raman spectroscopy (CSRS) fields produced in the first step of the cascade process, (c) for each delay time between the femtosecond impulsive pump and FSRS probe pulses, the line shape of the sidebands shows an inversion symmetry about the C-D stretch frequency, and this is due to the 180(∘) phase difference between the CARS and CSRS fields that produced the left and right sidebands, and (d) for each sideband, the line shape changes from positive Lorentzian to dispersive to negative Lorentzian, then to negative dispersive and back to positive Lorentzian with the period of the bending vibration, and it is correlated with the momentum of the wave packet prepared on the ground-state surface by the impulsive pump along the sideband normal coordinate.
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Affiliation(s)
- Bin Zhao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
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60
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Verhoefen MK, Bamann C, Blöcher R, Förster U, Bamberg E, Wachtveitl J. The photocycle of channelrhodopsin-2: ultrafast reaction dynamics and subsequent reaction steps. Chemphyschem 2011; 11:3113-22. [PMID: 20730849 DOI: 10.1002/cphc.201000181] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The photocycle of channelrhodopsin-2 is investigated in a comprehensive study by ultrafast absorption and fluorescence spectroscopy as well as flash photolysis in the visible spectral range. The ultrafast techniques reveal an excited-state decay mechanism analogous to that of the archaeal bacteriorhodopsin and sensory rhodopsin II from Natronomonas pharaonis. After a fast vibrational relaxation of the excited-state population with 150 fs its decay with mainly 400 fs is observed. Hereby, both the initial all-trans retinal ground state and the 13-cis-retinal K photoproduct are populated. The reaction proceeds with a 2.7 ps component assigned to cooling processes. Small spectral shifts are observed on a 200 ps timescale. They are attributed to conformational rearrangements in the retinal binding pocket. The subsequent dynamics progresses with the formation of an M-like intermediate (7 and 120 μs), which decays into red-shifted states within 3 ms. Ground-state recovery including channel closing and reisomerization of the retinal chromophore occurs in a triexponential manner (6 ms, 33 ms, 3.4 s). To learn more about the energy barriers between the different photocycle intermediates, temperature-dependent flash photolysis measurements are performed between 10 and 30°C. The first five time constants decrease with increasing temperature. The calculated thermodynamic parameters indicate that the closing mechanism is controlled by large negative entropy changes. The last time constant is temperature independent, which demonstrates that the photocycle is most likely completed by a series of individual steps recovering the initial structure.
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Affiliation(s)
- Mirka-Kristin Verhoefen
- Institute of Physical and Theoretical Chemistry, Johann Wolfgang Goethe University Frankfurt, Max von Laue-Straße 7, 60438 Frankfurt am Main, Germany
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61
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Kloz M, Grondelle RV, Kennis JT. Wavelength-modulated femtosecond stimulated raman spectroscopy—approach towards automatic data processing. Phys Chem Chem Phys 2011; 13:18123-33. [DOI: 10.1039/c1cp21650c] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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62
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Kawashima Y, Nakano H, Jung J, Ten-no S. A combined quantum mechanical and molecular mechanical method using modified generalized hybrid orbitals: implementation for electronic excited states. Phys Chem Chem Phys 2011; 13:11731-8. [DOI: 10.1039/c1cp20438f] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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63
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Yabushita A, Kobayashi T. Vibrational fine structures revealed by the frequency-to-time fourier transform of the transient spectrum in bacteriorhodopsin. J Phys Chem B 2010; 114:4632-6. [PMID: 20222701 DOI: 10.1021/jp9090014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A vibrational progression that is hidden in a featureless spectrum of induced absorption and stimulated emission was found in time-resolved absorption change spectra. The ultrahigh time resolution of the pump-probe measurement made by using an ultrashort laser pulse localizes the wave packet along the potential multimode hyper surfaces, represented by a vibrational progression. The transition energy of the induced absorption and stimulated emission corresponds to a localized point (space) on the hyper surface, which is visited by the wave packets with fixed phases.
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Affiliation(s)
- Atsushi Yabushita
- Department of Electrophysics, National Chiao-Tung University, 1001 Ta Hsueh Road, Hsinchu 3005, Taiwan.
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64
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Dioumaev AK, Wang JM, Lanyi JK. Low-temperature FTIR study of multiple K intermediates in the photocycles of bacteriorhodopsin and xanthorhodopsin. J Phys Chem B 2010; 114:2920-31. [PMID: 20136108 PMCID: PMC3820168 DOI: 10.1021/jp908698f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Low-temperature FTIR spectroscopy of bacteriorhodopsin and xanthorhodopsin was used to elucidate the number of K-like bathochromic states, their sequence, and their contributions to the photoequilibrium mixtures created by illumination at 80-180 K. We conclude that in bacteriorhodopsin the photocycle includes three distinct K-like states in the sequence bR (hv)--> I* --> J --> K(0) --> K(E) --> L --> ..., and similarly in xanthorhodopsin. K(0) is the main fraction in the mixture at 77 K that is formed from J. K(0) becomes thermally unstable above approximately 50 K in both proteins. At 77 K, both J-to-K(0) and K(0)-to-K(E) transitions occur and, contrarily to long-standing belief, cryogenic trapping at 77 K does not produce a pure K state but a mixture of the two states, K(0) and K(E), with contributions from K(E) of approximately 15 and approximately 10% in the two retinal proteins, respectively. Raising the temperature leads to increasing conversion of K(0) to K(E), and the two states coexist (without contamination from non-K-like states) in the 80-140 K range in bacteriorhodopsin, and in the 80-190 K range in xanthorhodopsin. Temperature perturbation experiments in these regions of coexistence revealed that, in spite of the observation of apparently stable mixtures of K(0) and K(E), the two states are not in thermally controlled equilibrium. The K(0)-to-K(E) transition is unidirectional, and the partial transformation to K(E) is due to distributed kinetics, which governs the photocycle dynamics at temperatures below approximately 245 K (Dioumaev and Lanyi, Biochemistry 2008, 47, 11125-11133). From spectral deconvolution, we conclude that the K(E) state, which is increasingly present at higher temperatures, is the same intermediate that is detected by time-resolved FTIR prior to its decay, on a time scale of hundreds of nanoseconds at ambient temperature (Dioumaev and Braiman, J. Phys. Chem. B 1997, 101, 1655-1662), into the K(L) state. We were unable to trap the latter separately from K(E) at low temperature, due to the slow distributed kinetics and the increasingly faster overlapping formation of the L state. Formation of the two consecutive K-like states in both proteins is accompanied by distortion of two different weakly bound water molecules: one in K(0), the other in K(E). The first, well-documented in bacteriorhodopsin at 77 K where K(0) dominates, was assigned to water 401 in bacteriorhodopsin. The other water molecule, whose participation has not been described previously, is disturbed on the next step of the photocycle, in K(E), in both proteins. In bacteriorhodopsin, the most likely candidate is water 407. However, unlike bacteriorhodopsin, the crystal structure of xanthorhodopsin lacks homologous weakly bound water molecules.
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Affiliation(s)
- Andrei K. Dioumaev
- Department of Physiology & Biophysics, University of California, Irvine, CA 92697
| | - Jennifer M. Wang
- Department of Physiology & Biophysics, University of California, Irvine, CA 92697
| | - Janos K. Lanyi
- Department of Physiology & Biophysics, University of California, Irvine, CA 92697
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Niu K, Zhao B, Sun Z, Lee SY. Analysis of femtosecond stimulated Raman spectroscopy of excited-state evolution in bacteriorhodopsin. J Chem Phys 2010; 132:084510. [DOI: 10.1063/1.3330818] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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66
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Dioumaev AK, Lanyi JK. Two bathointermediates of the bacteriorhodopsin photocycle, from time-resolved nanosecond spectra in the visible. J Phys Chem B 2009; 113:16643-53. [PMID: 19994879 PMCID: PMC3808455 DOI: 10.1021/jp907393m] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Time-resolved measurements were performed on wild-type bacteriorhodopsin with an optical multichannel analyzer in the spectral range 350-735 nm, from 100 ns to the photocycle completion, at four temperatures in the 5-30 degrees C range. The intent was to examine the possibility of two K-like bathochromic intermediates and to obtain their spectra and kinetics in the visible. The existence of a second K-like intermediate, termed KL, had been postulated (Shichida et al., Biochim. Biophys. Acta 1983, 723, 240-246) to reconcile inconsistencies in data in the pico- and microsecond time domains. However, introduction of KL led to a controversy, since neither its visible spectrum nor its kinetics could be confirmed. Infrared data (Dioumaev and Braiman, J. Phys. Chem. B 1997, 101, 1655-1662) revealed a state which might have been considered a homologue to KL, but it had a kinetic pattern different from that of the earlier proposed KL. Here, we characterize two distinct K-like intermediates, K(E) ("early") and K(L) ("late"), by their spectra and kinetics in the visible as revealed by global kinetic analysis. The K(E)-to-K(L) transition has a time constant of approximately 250 ns at 20 degrees C, and describes a shift from K(E) with lambda(max) at approximately 600 nm and extinction of approximately 56,000 M(-1) x cm(-1) to K(L) with lambda(max) at approximately 590 nm and extinction of approximately 50,000 M(-1) x cm(-1). The temperature dependence of this transition is characterized by an enthalpy of activation of DeltaH(++) approximately 40 kJ/mol and a positive entropy of activation of DeltaS(++)/R approximately 4. The consequences of multiple K-like states for interpreting the spectral evolution in the early stages of the photocycle are discussed.
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Affiliation(s)
- Andrei K Dioumaev
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697, USA.
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