BPS2026 – Vesicle budding through membrane asymmetry: Lipid phase transitions and asymmetric insertion

Temperature dependence of the light-induced spectral shift of carotenolds in Cyanidium caldarium and higher plant leaves. Evidence for an effect of the physical phase of chloroplast membrane lipids on the permeability of the membrane to ions

We have studied the interaction of melittin with lecithin bilayer membranes. Fluorescence polarisation measurements were performed beside the use of excimer forming pyrene derivatives.1. Diphenyl hexatriene, a fluorescence polarisation probe, was used to investigate the lipid phase transition. Addition of melittin leads to an increase of the transition temperature. Characteristic breaks were obtained plotting Tu as a function of the melittin concentration. The change in the width of the phase transition gives an indication of phase separation phenomenon.2. Pure pyrene lecithin membranes were agitated by melittin. A dramatic decrease in the excimer to monomer ratio was observed showing the same characteristic breaks.3. No change in the lipid phase transition temperature was obtained using pyrene decanoic acid and pyrene lecithin as probe molecules. Pyrene lecithin is involved in the lipid‐protein‐complex and therefore prevented from undergoing the lipid phase transition. Rigid patches surrounding the peptide molecule were formed. The pyrene decanoic acid is squeezed out from these regions leading to an increase of the excimer yield in the bulk lipid.4. High melittin concentration (c > 10 mole‐%) leads to a membrane disruption followed by the formation of a stable melittin micell furnished with lipids.

Fast Membrane Dynamics in Planar Suspended Lipid Bilayers Revealed by Single Particle Tracking

CHAPTER 3 - Lipid Phase Transitions and Mixtures

The purified Na+,Mg2(+)-ATPase from the Acholeplasma laidlawii B plasma membrane was reconstituted with dimyristoyl phosphatidylcholine and the lipid thermotropic phase behavior of the proteoliposomes formed was investigated by differential scanning calorimetry. The effect of this ATPase on the host lipid phase transition is markedly dependent on the amount of protein incorporated. At low protein/lipid ratios, the presence of increasing quantities of ATPase in the proteoliposomes increases the temperature and enthalpy while decreasing the cooperativity of the dimyristoyl phosphatidylcholine gel to liquid-crystalline phase transition. At higher protein/lipid ratios, the incorporation of increasing amounts of this enzyme does not further alter the temperature and cooperativity of the phospholipid chain-melting transition, but progressively and markedly decreases the transition enthalpy. Plots of lipid phase transition enthalpy versus protein concentration suggest that at the higher protein/lipid ratios each ATPase molecule removes approximately 1000 dimyristoyl phosphatidylcholine molecules from participation in the cooperative gel to liquid-crystalline phase transition of the bulk lipid phase. These results indicate that this integral transmembrane protein interacts in a complex, concentration-dependent manner with its host phospholipid and that such interactions involve both hydrophobic interactions with the lipid bilayer core and electrostatic interactions with the lipid polar head groups at the bilayer surface.

Lipid Droplet Phase Transition in Freezing Cat Embryos and Oocytes Probed by Raman Spectroscopy

Nonlinear Effect of Sucrose on Lamellar-Hexagonal Phase Transition Kinetics

New spirit of an old technique: Characterization of lipid phase transitions via UV/Vis spectroscopy

Lipid and protein composition and thermotropic lipid phase transitions in fatty acid-homogeneous membranes of Acholeplasma laidlawii B

Phase transitions in microsomal membranes from chilling sensitive and chilling resistant tomato plants and fruit

Phase transitions in lipids. Possible switch processes in biological membranes

Phase Transitions in Lipids in Relation to the Structure of Membranes

Fusion and lipid exchange in vesicles containing lipophilic spin labels

In this study, Fourier transform infrared, Raman and Brillouin spectroscopy have been used to study lipid phase behavior of hydrated as well as dried multilamellar l‐α‐phosphatidylcholine assemblies, in order to compare limitations and potentials of the different techniques. Dried lipid samples have been studied in the presence and absence of trehalose, which is known to affect the phase behavior of these systems. The methylene C‐H stretching (2800–3000 cm−1) region in infrared (IR) and Raman spectra provided mutually consistent information on the rearrangement of lipid acyl chains occurring at the lipid melting temperature. IR spectra have a higher signal‐to‐noise ratio, thus permitting a more precise evaluation of the melting temperature. In the hydrated lipid samples, the C‐H stretching region in the Raman spectra is less affected by the contribution of water compared with that in the IR spectra. Raman spectra are particularly suitable to simultaneously study both lipid and water contributions allowing to distinguish ice from non‐frozen water below 0 °C. Brillouin light scattering was used to probe the collective dynamics, i.e. the propagation velocity and the attenuation of longitudinal acoustic modes in the lipid samples. Lipid phase transitions are evident from a change in the temperature behavior of the acoustic velocity. Moreover, a strong relaxation process with a characteristic time of 14 ps was observed in the sample dried without trehalose with a maximum in acoustic attenuation at about 45 °C, which likely reflects the rearrangement of acyl chains. Copyright © 2015 John Wiley & Sons, Ltd.

Cholesterol and melatonin regulated membrane fluidity does not affect the membrane breakage triggered by amyloid-beta peptide