Anisotropic Optical Constants of Bacteriorhodopsin in the Mid-Infrared: Consequence on the Determination of α-Helix Orientation

Blaudez, D.; Boucher, François; Buffeteau, Thierry; Desbat, Bernard; Grandbois, Michel; Salesse, Christian

doi:10.1366/0003702991945551

Cited by 35 publications

(23 citation statements)

References 31 publications

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“…Recently, we have used this approach to determine out-of-plane optical constants of single monolayers of peptides and proteins from calibrated PM-IR RAS spectra. 40,41 This two-step calibration procedure can be stopped at the rst level when the bare substrate is not available or presents some contaminations. Finally, since the full expression of the PM -IRRAS signal has been considered (the J 0 term is not neglected), this approach can be extended to PM-IR RAS spectra of ultrathin lms deposited onto nonmetallic substrates.…”

Section: Co Nclusio Nmentioning

confidence: 99%

Calibration Procedure to Derive IRRAS Spectra from PM-IRRAS Spectra

et al. 2000

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A calibration procedure is presented to relate Fourier transform infrared reflection-absorption spectroscopy (IRRAS) spectra obtained by polarization modulation (PM) and conventional techniques. This procedure concerns only PM-IRRAS measurements obtained with a lock-in amplifier. At the first stage, it consists in measuring two calibrated spectra, by adding a linear polarizer after the sample. The corresponding corrected PM-IRRAS spectra display band intensities close to those observed on IRRAS spectra (at about 6%), but the value of the baseline is lower. The calibration procedure can be performed at the second stage, by normalizing the corrected PM-IRRAS spectra of the sample and the bare substrate. In this case, the band intensities and the baseline of the normalized corrected PM-IRRAS and IRRAS spectra are similar.

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Section: Co Nclusio Nmentioning

confidence: 99%

Calibration Procedure to Derive IRRAS Spectra from PM-IRRAS Spectra

et al. 2000

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“…Two measurements are required at each wavenumber to determine n and k. Under some circumstances one of these measurements can be replaced by the Kramers-Kronig relationships, which allow the n and k spectra to be interconverted provided the measurements cover a sufficiently wide wavenumber range and n is known at a given wavenumber (in the visible for example). Thus, optical constants can be determined from only one experimental spectrum such as external reflection at near-normal incidence for bulk materials, 38,39 transmission at normal incidence for liquids and thin films deposited on solid substrates, [40][41][42][43][44][45][46][47][48][49] or ATR. [50][51][52][53][54][55][56][57][58][59] The transmission method is particularly valuable for weak and moderately strong bands, whereas the ATR method can be applied to strong bands using the correction algorithm developed by Dignam et al 54 In the present work, the possible distortions of the IR spectra of ILs are first described.…”

Section: Introductionmentioning

confidence: 99%

Infrared Spectroscopy of Ionic Liquids: Quantitative Aspects and Determination of Optical Constants

2010

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The infrared (IR) spectra of ionic liquids involving 1-butyl-3-methylimidazolium (BMI) and the (CF(3)SO(2))(2)N(-), BF(4)(-), or PF(6)(-) anions, recorded in the transmission and attenuated total reflection (ATR) modes, exhibit strong differences in the most intense anion absorption profiles. These distortions come from optical effects and make difficult any quantitative analysis of, for example, the antisymmetric stretching vibrations of the BF(4)(-) and PF(6)(-) anions. A method is proposed to determine the optical constants, from which any type of experimental spectrum can be simulated. It is then possible to use the anion vibrational bands as spectroscopic probes of the local interactions occurring in the neat ionic liquids and in solutions. This is illustrated by a direct identification of ion pairs and separated ions in the IR spectra of BMI-PF(6) solutions.

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“…34 These bands are overlapped by the OH 2 bending band. The shoulder at 1652 cm -1 on the other hand is shifted to lower energies with compression and is associated with the CO stretching in R-helix structures, 35 changing their orientation with compression. We also observe a drastic change in the position of the vibration absorption peaks when compared to a pure GO x adsorbing at the air-water interface (inset of Figure 7B), in the same conditions for the GO x -PdNp adsorbing at the air-water interface.…”

Section: ' Results and Discussionmentioning

confidence: 66%

Monolayer Collapse Regulating Process of Adsorption−Desorption of Palladium Nanoparticles at Fatty Acid Monolayers at the Air−Water Interface

et al. 2011

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In this paper, we investigate the affinity of palladium nanoparticles, stabilized with glucose oxidase, for fatty acid monolayers at the air-water interface, exploiting the interaction between a planar system and spheroids coming from the aqueous subphase. A decrease of the monolayer collapse pressure in the second cycle of interface compression proved that the presence of the nanoparticles causes destabilization of the monolayer in a mechanism driven by the interpenetration of the enzyme into the bilayer/multilayer structure formed during collapse, which is not immediately reversible after monolayer expansion. Surface pressure and surface potential-area isotherms, as well as infrared spectroscopy [polarization modulation infrared reflection adsorption spectroscopy (PM-IRRAS)] and deposition onto solid plates as Langmuir-Blodgett (LB) films, were employed to construct a model in which the nanoparticle has a high affinity for the hydrophobic core of the structure formed after collapse, which provides a slow desorption rate from the interface after monolayer decompression. This may have important consequences on the interaction between the metallic particles and fatty acid monolayers, which implies the regulation of the multifunctional properties of the hybrid material.

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Anisotropic Optical Constants of Bacteriorhodopsin in the Mid-Infrared: Consequence on the Determination of α-Helix Orientation

Cited by 35 publications

References 31 publications

Calibration Procedure to Derive IRRAS Spectra from PM-IRRAS Spectra

Calibration Procedure to Derive IRRAS Spectra from PM-IRRAS Spectra

Infrared Spectroscopy of Ionic Liquids: Quantitative Aspects and Determination of Optical Constants

Monolayer Collapse Regulating Process of Adsorption−Desorption of Palladium Nanoparticles at Fatty Acid Monolayers at the Air−Water Interface

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