Time-resolved resonance Raman spectroscopy of photobiological and photochemical transients

Terner, James; El‐Sayed, Mostafa A.

doi:10.1021/ar00119a002

Cited by 35 publications

(10 citation statements)

References 110 publications

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“…We use a hybrid of kinetic spectroscopy and resonance Raman spectroscopy known as "time-resolved resonance Raman spectroscopy", by which it is possible to obtain resonance Raman spectra of short-lived chemical species such as chemical intermediates and excited states [18]. Resonance Raman spectroscopy can thus provide more detailed molecular structural information for short-lived species than is obtainable using transient absorption techniques.…”

Section: Heme-linked Ionizationmentioning

confidence: 99%

“…1055 Raman Scattering, Luminescence, and Spectroscopic Instrumentation in Technology (1989) / 271 protein active site [17]. We use a hybrid of kinetic spectroscopy and resonance Raman spectroscopy known as "time-resolved resonance Raman spectroscopy ", by which it is possible to obtain resonance Raman spectra of short -lived chemical species such as chemical intermediates and excited states [18].…”

Section: Introductionmentioning

confidence: 99%

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Resonance Raman Spectroscopy Of Peroxidase Intermediates

1989

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Section: Heme-linked Ionizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Resonance Raman Spectroscopy Of Peroxidase Intermediates

1989

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“…The vibrational spectra are greatly simplified when the laser is tuned to the electronic absorption wavelength of the retinal, because only retinal vibrations which mimic a molecular distortion in the excited state are enhanced. Using microbeam and flow techniques with picosecond excitation and optical multichannel analyzer (OMA) detection, it has proven possible to detect the resonance Raman spectra of picosecond transients (for a review see Terner and El-Sayed, 1985).…”

Section: Introductionmentioning

confidence: 99%

Subpicosecond resonance Raman spectra of the early intermediates in the photocycle of bacteriorhodopsin

Berg

Du-Jeon-Jang

Bitting

et al. 1990

Biophysical Journal

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The resonance Raman spectra are presented for the species formed during the photocycle of bacteriorhodopsin (bR) on a timescale of 800-900 fs. In the ethylenic stretch region two intermediates were found with frequencies of 1,510 and 1,518 cm(-1), corresponding to species with optical absorption maxima at 660 and 625 nm, respectively. This leads to the assignment of the 1,518 cm(-1) band to the J(625) intermediate. In the fingerprint region, the appearance of a vibration at 1,195 cm(-1) strongly suggests that the isomerization indeed has taken place in a time less than the pulsewidth of our laser. This supports the previous proposals made on the basis of the optical spectra. The spectra are compared with those observed in tens of picoseconds up to nanoseconds.

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“…Vibrational spectroscopy has been the primary tool for determining the structure of the retinal chromophore in BR's early photointermediates (7). In a recent study, Smith et al (8) examined the conformation of the C14-C15 bond in K and L550 by recognizing that one characteristic of an s-cis bond is the -100 cm -1 lowering of the C14-C15 stretching mode.…”

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Bacteriorhodopsin's L550 intermediate contains a C14-C15 s-trans-retinal chromophore.

Fodor

Pollard

Gebhard

et al. 1988

Proc. Natl. Acad. Sci. U.S.A.

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Conformational changes of the retinal chromophore about the C14-C15 bond in bacteriorhodopsin (BR) have been proposed in models for the mechanism of light-driven proton transport. To determine the C14-C15 conformation in BR's Lsso intermediate, we have examined the resonance Raman spectra of BR derivatives regenerated with retinal deuterated at the 14 and 15 positions. Vibrational calculations show that the C14-2H and C15-2H rocking modes form symmetric (A) and antisymmetric (B) combinations in [14,15_2H]retinal chromophores. When there is a trans conformation about the single bond between C14 and C15 (14-s-trans), a small frequency separation or splitting is observed between the A and B modes, which are found at =970 cm-'. In 14-s-cis molecules, the splitting is large, and the Raman-active symmetric A mode is predicted at =850 cm -1.In addition, the monodeuterium rock should appear at an unusually low frequency (920 -930 cm ')in the 14-2H-labeled 14-s-cis molecules. These patterns are insensitive to computa- L5sO contains a 14-s-trans chromophore and suggest that only 14-s-trans structures are involved in the proton pumping photocycle of BR.Bacteriorhodopsin (BR) is an intrinsic membrane protein that functions as a light-driven proton pump in the bacterium Halobacterium halobium (1). The photocycle of BR begins with the photochemical all-trans-to-13-cis isomerization ofthe retinal prosthetic group in the parent pigment BR5.. The pigment then decays through the K and L550 intermediates, and the Schiff base nitrogen deprotonates producing M412. A number of models have been proposed to explain how isomerization and Schiff-base deprotonation are coupled to proton transport. Isomerization-driven charge separation is one widely accepted idea (2-4), and models involving a cis conformation at the single bond between C14 and C15 (14-s-cis) for the K and L550 intermediates have been proposed by Schulten and Tavan (5) and by Liu et al. (6).Vibrational spectroscopy has been the primary tool for determining the structure of the retinal chromophore in BR's early photointermediates (7). In a recent study, Smith et al. (8) examined the conformation of the C14-C15 bond in K and L550 by recognizing that one characteristic of an s-cis bond is the -100 cm -1 lowering of the C14-C15 stretching mode. The C14-C15 mode in L550 was assigned at ==1172 cm-1, close to the 1155 cm-1 value observed in later Fourier transform infrared studies (9). The absence of any large frequency-lowering of this mode compared with the 13-cis protonated Schiff base (PSB) suggested that the chromophore was 14-s-trans. Subsequent MNDO (modified neglect of differential overlap) calculations by Tavan and Schulten (10) confirmed the lowering of the C14-C15 stretching mode in s-cis conformers; however, they argued that by displacing the Schiff base counterion they could enhance the tr-electron delocalization sufficiently to counteract the geometric effect of s-cis isomerization. While there is no direct support for their assumed counterion distances, ...

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Time-resolved resonance Raman spectroscopy of photobiological and photochemical transients

Cited by 35 publications

References 110 publications

Resonance Raman Spectroscopy Of Peroxidase Intermediates

Resonance Raman Spectroscopy Of Peroxidase Intermediates

Subpicosecond resonance Raman spectra of the early intermediates in the photocycle of bacteriorhodopsin

Bacteriorhodopsin's L550 intermediate contains a C14-C15 s-trans-retinal chromophore.

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