Phosphatidylcholine bilayer membranes

Affinities of lanthanide ions for phosphatidylcholine bilayer membranes. 

Stockton, G. W. and Smith, I. C. P. (1976). A deuterium NMR smdy of the condensing effect of cholesterol on egg phosphatidylcholine bilayer membranes. 1. Per-deuterated fatty acid probes. Chem. Phys. Lipids 77 251. 

Ferritto, M.S. and D.A. Tirrell, Photoregulation of the binding of a synthetic polyelectrolyte to phosphatidylcholine bilayer membranes. Macromolecules, 1988, 21, 3117-3119. 

McLaughlin A, Grathwohl C, McLaughlin S (1978) Adsorption of divalent-catimis to phosphatidylcholine bilayer membranes. Biochim Biophys Acta 513 338-357... 

Akutsu H, Seelig J (1981) Interaction of metal-ions with phosphatidylcholine bilayer-membranes. Biochemistry 20 7366-7373... 

Rybar P, Krivanek R, Samuely T, Lewis RNAH, McElhaney RN, Hianik T (2007) Study of the interaction of an a-helical transmembrane peptide with phosphatidylcholine bilayer membranes by means of densimetry and ultrasound velocimetry. Biochim Biophys Acta 1768(6) 1466 1478... 

When these lipids are dispersed in water, they spontaneously form bilayer membranes (also called lamellae) which are composed of two monolayer sheets of lipid molecules with their hydrophobic surfaces facing one another and their hydrophilic surfaces contacting the aqueous medium. In the case of phospholipids such as phosphatidylcholine (10.50), the structure consists of ... 

Rytdmaa, M., and Kinnunen, P.K.J., 1995, ReversibUity of the binding of cytochrome c to Uposomes. Implications for lipid-protein interactions./. B/oZ. Chem., 270 3197-3202 Salamon, Z., and ToUin, G., 1996, Surface plasmon resonance studies of complex formation between cytochrome c and bovine cytochrome c oxidase incorporated into a supported planar Upid bUayer. II. Binding of cytochrome c to oxidase-containing cardiohpin /phosphatidylcholine membranes. Biophys. J., 71 858-867 Salamon, Z., and ToUin, G., 1997, Interaction ofhorse heart cytochrome c with Upid bilayer membranes effects on redox potentials. J. Bioenerg. Biomembr. 29 211-221 Scarlett, J.L., and Murphy, M.P., 1997, Release of apoptogenic proteins from the... 

Fig. 2. Phase diagram describing lateral phase separations in the plane of bilayer membranes for binary mixtures of dielaidoylphosphatidylcholine (DEPC) and dipalmitoyl-phosphatidylcholine (DPPC). The two-phase region (F+S) represents an equilibrium between a homogeneous fluid solution F (La phase) and a solid solution phase S presumably having monoclinic symmetry (P(J. phase) in multilayers. This phase diagram is discussed in Refs. 19, 18, 4. The phase diagram was derived from studies of spin-label binding to the membranes.

We report here the results of a study of the adsorption of the alkaline earth cations to bilayer membranes formed from phosphatidylcholines with saturated chains dipalmitoyl phosphatidyl choline (DPPC) and dimyristoyl phosphatidyl choline (DMPC). Our salient result is that the adsorption of calcium is distinct from the other alkaline earth cations in two respects. First, only calcium adsorbs significantly more strongly to PCs with saturated chains than to phosphatidyl cholines with unsaturated chains, even when all lipids are present in the liquid crystalline state. Second, when the membranes are present in the frozen or gel state, the binding of calcium is significantly enhanced. We used two independent techniques to demonstrate this unique behavior of calcium. 

Lewis RNAH, Winter I, Kriechbaum M et al (2001) Studies of the structure and organization of cationic lipid bilayer membranes calorimetric, spectroscopic, and x-ray diffraction studies of linear saturated P-O-ethyl phosphatidylcholines. Biophys J 80 1329-1342... 

The conventional model developed to explain cell membrane characteristics influencing drug permeability is routinely referred to as the fluid-mosaic model (Figures 2.1 and 2.2). In this model the main components, for our purposes, are a phospholipid (e.g., sphingomyelin and phosphatidylcholine) bilayer (8 nm), with polar moieties at both the external and internal surfaces, and with proteins periodically traversing the phospholipid plane perpendicularly. 

Since the solidity or fluidity of the bilayer membrane is likely to depend on the alkyl chain interactions and consequently their length, an understanding of the relationship between chain order and chain length for tightly packed monolayers of phospholipids are important. As an example of how VSFS can be employed to study phospholipids at a liquid surface, a series of saturated symmetric chain phosphatidylcholines (PCs) were examined at the air/water and CCfr/water interfaces [49]. At the air/D20 interface, chain order within the monolayer was found to increase as the length of the chains increased (Figure 2.9a) under conditions of constant phospholipid head group area. 

The permeability to ions of dioleoylphosphatidylcholine (23) and diphytanoyl phosphatidylcholine (23 ) membranes was examined in the presence of Eu(fod)3, Pr(fod)3 and Eu(dpm)3. Ion permeability of both lipid bilayers was enhanced in the presence of Eu(fod)3 but not Eu(dpm)3. The magnitudes of the shifts were used to gain information on the location of the Eu(fod)3 in the membrane, and indicated that the europium chelate accumulated in the inner lipid layers of the two membranes and not in the central region between the two lipid layers" . 

Langner M, Hui SW. Merocyanine interaction with phosphatidylcholine bilayers. Biochim. Biophys. Acta. 1993 1149 175-179. Ross E, Bedlack RS, Loew EM. Dual-wavelength ratiometric fluorescence measurement of the membrane dipole potential. Biophys. J. 1994 67 208-216. 

Phospholipids are essential components of cell membranes and liposomes, which are closed spherical vesicles with an inner aqueous core and an outer shell composed of phospholipid bilayer membranes. Depending on the level of hydrophobicity, moderately hydrophobic drugs can be solubilized by liposomes if the drug becomes encapsulated or intercalated within the liposome. The phospholipids in commercially available injectable formulations include hydrogenated soy phosphatidylcholine, dimyristoylphosphatidyl-choline, egg phosphatidylglycerol, distearoylphospha-tidylglycerol, and dimyristoylphosphatidylglycerol. 

These results show clearly that most of the MgOEP is located near the inner vesicle surface although much smaller than the outer surface. A similar conclusion has been drawn previously for chlorophyll a dissolved in egg phosphatidylcholine vesicles. The inner part of the bilayer membrane of small vesicles is obviously a more suitable solvent or better liquid than the outer part, which is again reasonably explained by the much higher curvature of the inner part. Furthermore, at the centre of the bilayer, the same space is occupied by about half as many molecules. Several amphiphilic porphyrins with long side chains vesiculate upon sonification. The porphyrin then becomes part of the hydro-phobic core. ... 

Another well-defined synthetic membrane is a planar bilayer membrane. structure can be formed across a 1 - mm hole in a partition between two aqueous compartments by dipping a fine paintbrush into a membrane-forming solution, such as phosphatidylcholine in decanc, and stroking the tip of the brush across the hole. The lipid film across the hole thins spontaneously into a lipid bilayer. The electrical conduction properties of this macroscopic bilayer membrane are readily studied by inserting electrodes into each aqueous compartment (Figure 12.14). For example, its permeability to ions is determined by measuring the current across the membrane as a function of the applied voltage. 

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