Search results for "bilayer"

Improved stability of black lipid membranes by coating with polysaccharide derivatives bearing hydrophobic anchor groups

1986

Abstract Black lipid membranes were coated with modified polysaccharides bearing hydrophobic palmitoyl and cholesteryl moieties. The changes in membrane structure were investigated using dipicrylamine, a lipophilic ion, as membrane probe. The kinetics of ion transport through the black lipid membranes were studied using the charge pulse relaxation technique. With this technique it was found that it is possible to detect the insertion of the hydrophobic anchor groups of the polysaccharides into the membrane bilayer. As a result of the surface coating, these membranes exhibit a drastically increased long-term stability.

Role of calcium in the adhesion and fusion of bilayers.

1993

The interaction forces and fusion mechanisms of mixed zwitterionic-anionic phospholipid bilayers were measured with the surface forces apparatus. The bilayers were 3:1 mixtures of either dimyristoylphosphatidylcholine and dimyristoylphosphatidylglycerol (DMPC/DMPG) or dilauroylphosphatidylcholine and dilauroylphosphatidylglycerol (DLPC/DLPG), and experiments were carried out in NaCl solutions with and without CaCl2. In NaCl solutions, the forces between either mixed bilayer system were consistent with the DLVO (Derjaguin-Landau-Verwey-Overbeek) theory of repulsive electrostatic and attractive van der Waals forces, and fusion did not occur. At high pH (> 6) and in high (20 mM) NaCl concentra…

Polymer-supported bilayer on a solid substrate

1992

Sterols and Steroids

1994

Sterols and steroids, like the terpenes and carotinoids, are isoprene derivatives. The sterols are components of the membranes of all eukaryotic cells and they bind and condense the phospholipid bilayer. The outer cell membrane is particularly rich in sterols, with a molar ratio of sterols to phospholipids of 0.8–0.1, compared with the usual value of 0.1–0.3 for intracellular membranes. The parent substance of all sterols is cholesterol (Fig. 16.1). The sterols are classified with the steroid hormones and bile salts as steroids because they also have the gonan (formerly steran) four-ring system and have their biosynthetic origin in cholesterol. Steroids with hormonal functions are known fro…

Scanning Force Microscopy of Artificial Membranes

2002

Visualization of biological membranes by scanning force microscopy (SFM) has tremendously improved the current understanding of protein ‐ lipid interactions under physiological conditions. SFM is the only tool to directly image processes on surfaces in aqueous solution at molecular resolution. Besides being a supportive means to confirm results on lipid phases and domains obtained from fluorescence spectroscopy, calorimetry, and X-ray crystallography, SFM has contributed distinct aspects on the formation of 2D crystals of various membrane-confined proteins and morphological changes of membranes due to the interaction of peptides and proteins. This review will focus on recent results in SFM …

Polymerization in black lipid membranes. Influence on ion transport

1986

A variety of different lipids containing dienoyl groups in the side chains were tested for membrane formation using the planar lipid bilayer approach. One of these lipids formed stable bilayers which could be polymerized using UV-illumination. The influence of the polymerization was studied in monolayers, lipid vesicles and planar bilayers. The stability of the lipid bilayer membranes was increased by polymerization. Thus, the lifetime of the membranes increased from about 1 h to 4–5 h or longer. Furthermore, the specific conductance of unmodified membranes and of carrier-mediated transport is reduced. The transport of lipophilic ions was investigated as a function of polymerization using t…

Temperature and polymer crosslinking degree influence on drug transfer from alpha,beta-polyasparthydrazide hydrogel to model membranes. A calorimetri…

1998

Abstract A non-steroidal anti-inflammatory drug, diflunisal, has been chosen as drug model to be incorporated in α , β -polyasparthydrazide (PAHy) matrices to study the effect of polymer crosslinking degrees on the release processes from hydrogel ( X =0.4 and X =0.8) to a model membrane represented by unilamellar vesicles of dipalmitoylphosphatidylcholine. The technique employed to monitor these processes was differential scanning calorimetry that appears to be particularly suitable to follow the transfer kinetics of a drug from a controlled release system to void biomembrane model. The drug release from the two PAHy hydrogels differently crosslinked by glutaraldehyde to the lipidic model w…

Synthesis and Functional Reconstitution of Light-Harvesting Complex II into Polymeric Membrane Architectures.

2015

One of most important processes in nature is the harvesting and dissipation of solar energy with the help of light-harvesting complex II (LHCII). This protein, along with its associated pigments, is the main solar-energy collector in higher plants. We aimed to generate stable, highly controllable, and sustainable polymer-based membrane systems containing LHCII-pigment complexes ready for light harvesting. LHCII was produced by cell-free protein synthesis based on wheat-germ extract, and the successful integration of LHCII and its pigments into different membrane architectures was monitored. The unidirectionality of LHCII insertion was investigated by protease digestion assays. Fluorescence …

Derivation of coarse-grained simulation models of chlorophyll molecules in lipid bilayers for applications in light harvesting systems

2015

The correct interplay of interactions between protein, pigment and lipid molecules is highly relevant for our understanding of the association behavior of the light harvesting complex (LHCII) of green plants. To cover the relevant time and length scales in this multicomponent system, a multi-scale simulation ansatz is employed that subsequently uses a classical all atomistic (AA) model to derive a suitable coarse grained (CG) model which can be backmapped into the AA resolution, aiming for a seamless conversion between two scales. Such an approach requires a faithful description of not only the protein and lipid components, but also the interaction functions for the indispensable pigment mo…

Mg2+-binding shifts the IM30 activity from membrane protection to membrane destabilization

2020

ABSTRACTThe inner membrane-associated protein of 30 kDa (IM30) is essential in chloroplasts and cyanobacteria. The spatio-temporal cellular localization of the protein appears to be highly dynamic and triggered by internal as well as external stimuli, mainly light intensity. A soluble fraction of the protein is localized in the cyanobacterial cytoplasm or the chloroplast stroma, respectively. Additionally, the protein attaches to the thylakoid membrane as well as to the chloroplast inner envelope or the cyanobacterial cytoplasmic membrane, respectively, especially under conditions of membrane stress. IM30 is involved in thylakoid membrane biogenesis and/or maintenance, where it either stabi…