Molecular orientation in thin Langmuir–Blodgett films of dipalmitoylphosphatidylcholine as studied by FTIR transmission and reflection–absorption spectroscopy

Okamura, Emiko; Umemura, Junzo; Takenaka, Tohru

doi:10.1139/v91-248

Cited by 19 publications

(20 citation statements)

References 11 publications

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“…LB films were made with a Kyowa Interface Science Co. Ltd. Model HBM LB film apparatus using previously described vertical dipping and horizontal lifting methods. 24 The compressing barrier was made of Teflon-coated aluminum. The compressing speed was 14.0 cm 2 /min.…”

Section: Methodsmentioning

confidence: 99%

“…26 Using only the LB technique, the transfer ratio of DPPC onto solid substrates is known to be low, especially for the upper layers. 24 Therefore, the successive layers were transferred according to a previously described horizontal lifting (HL) technique. [27][28][29] Thus, LB films composed of a total of 10 monolayers were assembled.…”

Section: Uv Absorption Analysismentioning

confidence: 99%

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UV Absorption Spectroscopic Analysis of the Molecular Orientation of a Drug Penetrated into a DPPC Membrane

et al. 1996

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The present study quantitatively measured, via UV absorption spectroscopy, the molecular orientation of the drug chlorpromazine (CPZ) after spontaneous penetration into the gel phase of a phospholipid membrane. An L-R-dipalmitoylphosphatidylcholine (DPPC) Langmuir (L) film (a monolayer on an aqueous solution) was doped with CPZ and transferred onto a quartz substrate to form a Langmuir-Blodgett (LB) film. The transmission spectrum of the LB film was measured using a normal incident, nonpolarized UV beam. To calculate the theoretical absorbances, the extinction coefficients of oriented CPZ molecules in the DPPC LB film were deduced from the molar extinction coefficients of nonoriented, dispersed CPZ molecules in an aqueous solution. The anisotropic extinction coefficient of CPZ was determined with the uniaxial refractive index ellipsoid model as a function of orientation angle, using the extinction coefficient of CPZ in the bulk state. By comparing the theoretical absorbances with observed absorbances, the orientation angles from the surface normal of the LB film of transition moments along the molecular short and long axes were determined to be 17°and 85°, respectively. The results of the present study indicate that CPZ molecules penetrate deep into the DPPC membranes and that the molecular orientation of CPZ is determined by the surrounding DPPC molecules.

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Section: Methodsmentioning

confidence: 99%

Section: Uv Absorption Analysismentioning

confidence: 99%

UV Absorption Spectroscopic Analysis of the Molecular Orientation of a Drug Penetrated into a DPPC Membrane

et al. 1996

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“…Attenuated total reflection (ATR) infrared measurements on lipid bilayers are well-established for obtaining structural information and for protein-lipid interaction studies (Tamm & Tatulian, 1993;Frey & Tamm, 1991;Okamura et al, 1986Okamura et al, , 1990Reinl & Bayerl, 1993;Ter-Minassian-Saraga et al, 1988). Recently, we have come to appreciate that the method provides one of the most sensitive tools to investigate the process of lipid transfer between a single supported bilayer and vesicles.…”

mentioning

confidence: 99%

Lipid Transfer between Small Unilamellar Vesicles and Single Bilayers on a Solid Support: Self-Assembly of Supported Bilayers with Asymmetric Lipid Distribution

Reinl¹,

Bayerl²

1994

Biochemistry

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The transfer of lipids between small unilamellar vesicles of either dimyristoylphosphatidylcholine (DMPC), dimyristoylphosphatidylglycerol (DMPG), or dioctadecyl diammonium bromide (DODAB) and a single bilayer on a solid support of chain perdeuterated DMPC-d54 has been studied by time-resolved ATR infrared spectroscopy, deuterium NMR, and DSC. The IR method was used for measuring the transfer kinetics and the amount of lipid transferred to the supported bilayer, while NMR was employed for the assessment of molecular order and for the occurrence of lipid asymmetries due to the transfer. We find that the composition of a supported planar dimyristoylphosphatidylcholine (DMPC-d54) bilayer can be modified by incubation with high concentrations of sonicated vesicles consisting of the donor lipid. Three cases were studied. First, the incubation was done with DMPC as donor lipid. The kinetics of this process is double exponential and comparatively slow, with a half-time in the range of several hours. The activation energy was estimated as 50 +/- 2 kJ/mol. In a second set of measurements, cationic DODAB or anionic DMPG was used as donor lipid. The kinetics of this transfer is 1 order of magnitude faster than for DMPC and can be described by a single exponential. For DMPG transfer, we obtained an activation energy of 35 +/- 2 kJ/mol. Independent of the headgroup charge of the donor lipid, 25-35% of the (acceptor) DMPC in the supported bilayer is not accessible for exchange with the donor lipid. The transfer of either DMPG or DODAB causes drastic changes of the phase transition behavior of the supported bilayer without significantly altering the lipid packing density of the lipids.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…Using the calculated angle between the transition dipole moment and surface normal, the average tilt angle of the helices, γ, with respect to the surface normal was calculated (eq S7 of the Supporting Information). The angle between the α-helix long axis and the transition moment of the amide I vibration (reference angle), α, was determined to be between 34° and 38°. − The tilt angle of the α-helix was calculated according to the procedure described elsewhere, and the details of these calculations are given in the Supporting Information.…”

Section: Resultsmentioning

confidence: 99%

Physicochemical Studies on Orientation and Conformation of a New Bacteriocin BacSp222 in a Planar Phospholipid Bilayer

Pieta

Majewska

Su³

et al. 2016

Langmuir

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The behavior, secondary structure, and orientation of a recently discovered bacteriocin-like peptide BacSp222 in a lipid model system supported at a gold electrode was investigated by chronocoulometry, polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), and attenuated total reflectance infrared (ATR-IR) spectroscopy. The IR spectra show that the secondary structure of BacSp222 is predominantly α-helical. Analysis of the spectra in the amide I region shows that the α-helical fragment of the peptide is inserted into bilayer at the potential range at which the bilayer is stable and attached to the Au(111) surface, i.e., from -0.5 to 0.3 V vs Ag/AgCl. Insertion of BacSp222 to the membrane significantly changes the conformation of the acyl chains of lipid molecules, from all-trans to partially melted; however, the chains become less tilted. Based on these results, we propose that BacSp222 interacts with the DMPC bilayer through the barrel-stave pore formation. In this model, α-helix of BacSp222 inserts into the membrane with an angle between the α-helix axis and membrane normal equal to ∼18°. The changes in orientation of the α-helical fragment of the peptide indicate that the orientation of BacSp222 with respect to the bilayer surface is potential-dependent. The peptide is inserted into the membrane driven by the electrostatic field generated by negative charge at the metal surface. It is not inserted at negative potentials where the membrane is detached from the metal and no longer exposed to the electrostatic field of the metal.

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Molecular orientation in thin Langmuir–Blodgett films of dipalmitoylphosphatidylcholine as studied by FTIR transmission and reflection–absorption spectroscopy

Cited by 19 publications

References 11 publications

UV Absorption Spectroscopic Analysis of the Molecular Orientation of a Drug Penetrated into a DPPC Membrane

UV Absorption Spectroscopic Analysis of the Molecular Orientation of a Drug Penetrated into a DPPC Membrane

Lipid Transfer between Small Unilamellar Vesicles and Single Bilayers on a Solid Support: Self-Assembly of Supported Bilayers with Asymmetric Lipid Distribution

Physicochemical Studies on Orientation and Conformation of a New Bacteriocin BacSp222 in a Planar Phospholipid Bilayer

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