Second-harmonic generation in purple membrane-poly(vinyl alcohol) films: probing the dipolar characteristics of the bacteriorhodopsin chromophore in bR570 and M412

Huang, Jung Y.; Chen, Zhongping; Lewis, Aaron

doi:10.1021/j100345a086

Cited by 124 publications

(96 citation statements)

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“…Assuming this polarizability has a major component in the direction of the retinal (23), these contributions are similar for all absorbing molecules. We emphasize that different conditions apply in the transparent, off-resonance regime, as illustrated by the observed strong polarization dependence of frequency doubling of 1,064-nm light in bR films by Lewis and coworkers (23).…”

Section: Resultsmentioning

confidence: 83%

“…Unlike the previous second harmonic generation measurements on bR (22)(23)(24)(25), which were conducted off-resonance and did not provide any temporal information on the polarization, this experiment was carried out at full resonance and with Ϸ11-fs time resolution. Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The second order susceptibility (2) of the retinal chromophore is unusually high, especially in its native protein environment, and this property has been shown to be a requirement for functioning of bR (21). These strong nonlinear characteristics have been demonstrated in (off-resonance) frequency up-conversion ( 32 ) experiments (22)(23)(24)(25). The same property should also give rise to functionally more relevant frequency downconversion ( 30) or optical rectification (26).…”

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confidence: 99%

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Resonant optical rectification in bacteriorhodopsin

Groma

Colonna

Lambry

et al. 2004

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

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The relative role of retinal isomerization and microscopic polarization in the phototransduction process of bacteriorhodopsin is still an open question. It is known that both processes occur on an ultrafast time scale. The retinal trans3cis photoisomerization takes place on the time scale of a few hundred femtoseconds. On the other hand, it has been proposed that the primary lightinduced event is a sudden polarization of the retinal environment, although there is no direct experimental evidence for femtosecond charge displacements, because photovoltaic techniques cannot be used to detect charge movements faster than picoseconds. Making use of the known high second-order susceptibility (2) of retinal in proteins, we have used a nonlinear technique, interferometric detection of coherent infrared emission, to study macroscopically oriented bacteriorhodopsin-containing purple membranes. We report and characterize impulsive macroscopic polarization of these films by optical rectification of an 11-fs visible light pulse in resonance with the optical transition. This finding provides direct evidence for charge separation as a precursor event for subsequent functional processes. A simple two-level model incorporating the resonant second-order optical properties of retinal, which are known to be a requirement for functioning of bacteriorhodopsin, is used to describe the observations. In addition to the electronic response, long-lived infrared emission at specific frequencies was observed, reflecting charge movements associated with vibrational motions. The simultaneous and phase-sensitive observation of both the electronic and vibrational signals opens the way to study the transduction of the initial polarization into structural dynamics.R etinal proteins play an essential role in a broad range of light-driven biological processes, including vision (1), energy transduction (2), and circadian control (3). All these functions involve both the conversion of light energy into charge separation and retinal isomerization, but the interplay of these processes is the subject of intense debate. The retinal protein of which the initial photochemistry is most extensively studied is the photosynthetic protein bacteriorhodopsin (bR). This protein colors the purple membrane of halobacteria and acts as a light-driven proton pump by means of a multistep process termed the photocycle (2). In the traditional model for the initial transduction step in this cycle is directly light-driven trans3cis isomerization of retinal (4-6); this model has been recently extended by including excited-state skeletal stretching (5, 7). However, experiments with modified bR containing nonisomerizable retinal analogs challenged this model by showing that the initial photo-induced events are not associated with retinal isomerization (8-10). In fact, in an early alternative hypothesis (11), the essential process was proposed to be dielectric relaxation of the protein as a response to sudden polarization upon retinal excitation (11-13). Recent molecular dynamic...

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Section: Resultsmentioning

confidence: 83%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Resonant optical rectification in bacteriorhodopsin

Groma

Colonna

Lambry

et al. 2004

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

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“…As a typical case, an interference effect of SH waves between two SHG-active media has been applied to the determination of absolute molecular orientation. [20][21][22][23][24][25][26][27][28] Basic experimental arrangements for Langmuir-Blodgett (LB) monolayer assemblies, as an example, are shown in Fig. 3.…”

Section: Shg Interferometrymentioning

confidence: 99%

Recent Progress in Analytical SHG Spectroscopy

Yamada

Lee

1998

ANAL. SCI.

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The progress of laser technology has brought extensive applications of nonlinear optical (NLO) spectroscopy to analytical fields. Especially, optical second harmonic generation (SHG), which is one of the most popular NLO phenomena, has been successfully applied to the study of interfaces (surfaces). Several fine reviews on surface SHG spectroscopies have appeared recently. The present article will concentrate on some new applications of SHG: second harmonic microscopy (SHM) for microstructural characterization, SHG interferometry for the determination of absolute molecular orientation, surface analysis of microstructures, and some molecular interactions at the interfaces.

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“…Yet, surprisingly, given the information that can be obtained about structures, orientational ordering and dynamics at interfaces, application of these techniques to the study of biological membranes has been extremely limited. There have been a few SHG experiments on bacteriorhodopsin [6], but despite these demonstrations of feasibility. systematic SHG studies of membranes or membrane-bound proteins have not been done and we are aware of no applications of the more informative SFG technique in biological systems.…”

mentioning

confidence: 99%

Sum frequency generation studies of membrane transport phenomena

Dyer¹,

Shreve²

1998

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Second-harmonic generation in purple membrane-poly(vinyl alcohol) films: probing the dipolar characteristics of the bacteriorhodopsin chromophore in bR570 and M412

Cited by 124 publications

References 0 publications

Resonant optical rectification in bacteriorhodopsin

Resonant optical rectification in bacteriorhodopsin

Recent Progress in Analytical SHG Spectroscopy

Sum frequency generation studies of membrane transport phenomena

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