Determination of bacteriorhodopsin orientation in monolayers by infrared spectroscopy

Méthot, Mario; Boucher, François; Salesse, Christian; Subirade, Muriel; Pézolet, Michel

doi:10.1016/s0040-6090(95)08407-x

Cited by 19 publications

(22 citation statements)

References 14 publications

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“…7±10 Bacteriorhodopsin was thus chosen because it is structurally very stable when spread in monolayers at the air/water interface compared to other proteins, 11,12 and it is very easy to handle. Moreover, it has been previously well characterized by ATR 13 and by electron 8,14 and Xray 9 diffraction, and it shows a de® ned orientation.…”

Section: Introductionmentioning

confidence: 98%

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

et al. 1999

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In this paper, we present the first determination of the anisotropic optical constants of a protein (bacteriorhodopsin or bR) monolayer in the mid-infrared range. This procedure has allowed us to calculate a mean tilt angle of the α-helices' axis with respect to the normal of the surface. Using these optical constants, we have been able to reproduce the polarized attenuated total reflection (ATR) spectra of a bR monolayer deposited on a germanium crystal. On the other hand, the optical constants have to be modified to reproduce the polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) spectrum of a bR monolayer spread at the air/water interface. This modification of the optical constants indicates that the α helices are more tilted when the bR monolayer is spread on the water surface than when it is deposited onto a dry solid substrate.

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Section: Introductionmentioning

confidence: 98%

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

et al. 1999

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“…However, studies concerning absorption of head groups, such as carboxylic and carboxylate groups of fatty acids [495][496][497], amide [498][499][500][501][502] and phosphate [503] groups of biophysical LB films (Section 7.7), and the CN groups of chromophoric molecules [504], have also been reported.…”

Section: Order-disorder Transitionmentioning

confidence: 99%

“…N(γ, φ, ψ) is the orientation distribution function, which is expressed by the common statistical formula. in the MO data obtained by Ahn et al [517a] for the LB films of stearates of Ca, Cd, and Pb deposited on Ge, etched Si, and oxidized Si and the difference in orientation of α-helix of the bacteriorhodopsin (bR) LB films, obtained by DR fitting [502] and spectrum fitting [568a].…”

Section: Orientationmentioning

confidence: 99%

Interpretation of IR Spectra of Ultrathin Films

2003

Handbook of Infrared Spectroscopy of Ultrathin Films

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Generally speaking, IR spectral measurements of ultrathin films are undertaken to determine (i) the chemical identity of adsorbed species (including dissociation fragments); (ii) the geometric or structural arrangement (orientation) of these species and their positions with respect to the surface atoms of the substrate; (iii) their vibrational, rotational, and translational motion on the surface; (iv) the charge distribution and energy level structure of the valence electrons in both adsorbate and substrate; and (v) the effects of external perturbations, such as the electric and magnetic fields, photons, electrons, heating, and surface pressure on factors (i)-(iv) [1]. However, such information cannot be extracted directly from the IR spectra of ultrathin films due to the strong dependence of the shape and relative intensity of the bands on the geometry of the experiment, the optical properties of the substrate, the surroundings, the gradient of the optical properties at the film-substrate interface and in the film itself, as well as on the film thickness, and the particle size in the case of powder or islandlike supports. These effects and their physical background are discussed in Sections 3.1-3.5 and 3.9. In addition, there can be an intensity transfer between modes of coadsorbed species and a change in the band position with surface coverage. This effect is used for determining the mode of the surface filling and the degree of intermixing of different species at the surface (Section 3.6). If the film under study is located at the electrode-solution interface, the resulting spectrum is made up of contributions of all species in the path of radiation that are affected by the electrode potential, which further complicates the interpretation. Apart from technical means (Chapter 4), there exist analytical and mathematical approaches to resolve contributions of different species in such a complex spectrum (Sections 3.7 and 3.8). Another feature of the IR spectra of ultrathin films that is perhaps surprising and unexpected is their sensitivity to the volume fraction, shape, and orientation of inhomogeneities (e.g., pores or inclusions) in the film. Moreover, if the characteristic size of the 140

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“…The study was performed using Fourier transform IR spectroscopy (FTIR) which has long been in use for studying the secondary structure of proteins in solutions [5] and, recently, in monolayers [6], LB films [7], YAMPOLSKAYA et al . adsorption layers on solid substrates [8,9], as well as in model biological membranes [10].…”

Section: Introductionmentioning

confidence: 99%

Secondary Structure of Globular Proteins in Adsorption Layers at the Solution-Air Interface by the Data of Fourier Transform IR Spectroscopy

2005

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The secondary structures of globular proteins of different structural types ( α , ( α + β ) , and β ) are studied in the adsorption layers at the solution-air interface using Fourier transform infrared spectroscopy. Similar investigations are performed for the initial proteins in a powdered state; these data are used as a control. It is shown that, at the water-air interface, either the secondary structure of the studied proteins changes insignificantly or remains intact depending on the structural type of a protein. The adsorption of proteins of the α -helical type (bovine and human serum albumins) and the ( α + β ) type (lysozyme) virtually do not result in changes in their secondary structure. A protein of β -structural type, α -chymotrypsin, shows a lower stability at the water-air interface.

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Determination of bacteriorhodopsin orientation in monolayers by infrared spectroscopy

Cited by 19 publications

References 14 publications

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

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

Interpretation of IR Spectra of Ultrathin Films

Secondary Structure of Globular Proteins in Adsorption Layers at the Solution-Air Interface by the Data of Fourier Transform IR Spectroscopy

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