Interactions of phospholipids

Various dynamic processes have been investigated using computer simulations of phospholipids. These include the dynamics of the alkyl chain movement of the phospholipid, the structure of water at the interface, diffusion of small molecules, interactions of phospholipids with water, dmgs, peptides, and proteins, and the effect of unsaturation or the presence of cholesterol on the phospholipid conformation. 

Blume, A., Jansen, M., Ghyczy, M. etal. Interaction of phospholipid liposomes with hpid model mixtures for stratum corneum lipids. Int. J. Pharm. 1993 99 219-28. 

Table 4. The heat effects calculated for the reactions occurring due to an interaction of phospholipids with a silica nanoparticle (PM3 method).

The assumption of increased OH ion concentration at the solution/air interface as a factor for the formation of negative (po is consistent with the observed independence of h on pH when Ca2+ ions are added, since in this case the specific interaction of phospholipid head... 

Thus far, the interactions of phospholipid head groups have been considered, because the model was applied toward rationalizing the membranolysis of eukaryotic cells such as erythrocytes, and PLs are the primary constituents of eukaryotic cell membranes. A reasonable question to ask at this time is whether the above results are relevant to prokaryotic membranes. Although PLs constitute a smaller proportion of the prokaryotic cell wall and cell membrane, the other constituent molecules such as liopolysaccharides and teichoic acids, are also amphiphilic. The general structure of a hydrophilic portion attached to a hydrophobic tail is common... 

Kazal, L. A., Interactions of Phospholipids with Lipoproteins, with Serum... 

Cornell DG and Patterson DL. Interaction of phospholipids in monolayers with P-lactoglobulin adsorbed from solution. J. Agric. Food Chem. 1989 37 1455-1459. 

Crowe JH, Whittam MA, Chapman D, Crowe LM (1984) Interactions of phospholipid monolayers with carbohydrates. Biochim Biophys Acta 769 151-159... 

Interactions of phospholipids in an aqueous medium and the formation of liposome vesicle. Phospholipids spontaneously form lipid bilayers in which the polar head groups interact with water, whereas the hydrophobic tails interact among themselves to form an environment that excludes water. The lipid bilayers are stabilized by noncovalent interactions. 

Fang N, et al. (2001). Interactions of phospholipid bilayer with chitosan effect of molecular weight and pH. Biomacromol. 2 1161-1168. 

Leonenko, Z. V., Carnini, A., and Cramb, D. T. 2000. Supported planar bilayer formation by vesicle fusion The interaction of phospholipid vesicles with surfaces and the effect of gramicidin on bilayer properties using atomic force microscopy, Biochim Biophys Acta 1509,131-147. 

Csucs G, Ramsden JJ. Interaction of phospholipid vesicles with smooth metal-oxide surfaces. Biochim Biophys Acta 1998 1369 61-70. 

A new class of phosphatidylcholine analogues (6) and (7) derived from glyceric acid has been prepared for studies of conformation and interaction of phospholipids in biological membranes, using fluorescence energy transfer (FRET) techniques (Scheme 1)." ... 

Rogerson, M.L. Interaction of Phospholipids with Fatty Acids. RhD diss., 2003, University of East Anglia, Norwich, U.K... 

Knowles, P.F., Watts, A., and Marsh, D., 1981, Spin label studies of headgroup specificity in the interaction of phospholipids with yeast cytochrome oxidase. Biochemistry, 20 5888. 

Chapman, D., and Penkett, S. A., 1966, Nuclear magnetic resonance spectroscopic studies of the interaction of phospholipids with cholesterol. Nature 211 1304. 

In an extensive SFA study of protein receptor-ligand interactions, Leckband and co-workers [114] showed the importance of electrostatic, dispersion, steric, and hydrophobic forces in mediating the strong streptavidin-biotin interaction. Israelachvili and co-workers [66, 115] have measured the Hamaker constant for the dispersion interaction between phospholipid bilayers and find A = 7.5 1.5 X 10 erg in water. 

A typical biomembrane consists largely of amphiphilic lipids with small hydrophilic head groups and long hydrophobic fatty acid tails. These amphiphiles are insoluble in water (<10 ° mol L ) and capable of self-organization into uitrathin bilaycr lipid membranes (BLMs). Until 1977 only natural lipids, in particular phospholipids like lecithins, were believed to form spherical and related vesicular membrane structures. Intricate interactions of the head groups were supposed to be necessary for the self-organization of several ten thousands of... 

Other Reactions of Phospholipids. The unsaturated fatty acid groups in soybean lecithin can be halogenated. Acetic anhydride combined with the amino group of phosphatidylethanolamine forms acetylated compounds. PhosphoHpids form addition compounds with salts of heavy metals. Phosphatidylethanolamine and phosphatidjhnositol have affinities for calcium and magnesium ions that are related to interaction with their polar groups. 

QUANTUM-CHEMICAL MODELLING OL PROCESSES OF INTERACTION OF ACTIVE FORMS OF OXYGEN WITH PHOSPHOLIPIDES... 

Tyrosine phosphorylated IRS interacts with and activates PI 3-kinase [3]. Binding takes place via the SRC homology 2 (SH2) domain of the PI 3-kinase regulatory subunit. The resulting complex consisting of INSR, IRS, and PI 3-kinase facilitates interaction of the activated PI 3-kinase catalytic subunit with the phospholipid substrates in the plasma membrane. Generation of PI 3-phosphates in the plasma membrane reemits phospholipid dependent kinases (PDKl and PDK2) which subsequently phosphorylate and activate the serine/threonine kinase Akt (synonym protein... 

Anchordoguy, T.J., Rudolph, A.S., Carpenter, J.F., Crowe, J.H. (1987). Modes of interaction of cryoprotectants with membrane phospholipids during freezing. Cryobiol. 24,324-331. 

Angiotensin II binds to specific adrenal cortex glomerulosa cell receptors. The hormone-receptor interaction does not activate adenylyl cyclase, and cAMP does not appear to mediate the action of this hormone. The actions of angiotensin II, which are to stimulate the conversion of cholesterol to pregnenolone and of corticosterone to 18-hydroxycorticosterone and aldosterone, may involve changes in the concentration of intracellular calcium and of phospholipid metabolites by mechanisms similar to those described in Chapter 43. 

The Gram-negative cell envelope (Fig. 1.4) is even more complicated essentially, it contains lipoprotein molecules attached covalently to the oligosaccharide backbone and in addition, on its outer side, a layer of lipopolysaccharide (LPS) and protein attached by hydrophobic interactions and divalent metal cations, Ca and Mg. On the inner side is a layer of phospholipid (PL). 

A further partihon system based on the use of liposomes, and commercialized under the name Transil [110, 111], has shown its utiUty as a UpophiUcity measure in PBPK modeling [112]. Fluorescent-labeled liposomes, called fluorosomes, are another means of measuring the rate of penetration of small molecules into membrane bilayers [113, 120]. Similarly, a colorimetric assay amenable to HTS for evaluating membrane interactions and penetrahon has been presented [116]. The platform comprises vesicles of phospholipids and the chromahc Upid-mimehc polydiacetylene. The polymer undergoes visible concentrahon-dependent red-blue transformahons induced through interactions of the vesicles with the studied molecules. 

The lag-phase measurement at 234 nm of the development of conjugated dienes on copper-stimulated LDL oxidation is used to define the oxidation resistance of different LDL samples (Esterbauer et al., 1992). During the lag phase, the antioxidants in LDL (vitamin E, carotenoids, ubiquinol-10) are consumed in a distinct sequence with a-tocopherol as the first followed by 7-tocopherol, thereafter the carotenoids cryptoxanthin, lycopene and finally /3-carotene. a-Tocopherol is the most prominent antioxidant of LDL (6.4 1.8 mol/mol LDL), whereas the concentration of the others 7-tocopherol, /3-carotene, lycopene, cryptoxanthin, zea-xanthin, lutein and phytofluene is only 1/10 to 1/300 of a-tocopherol. Since the tocopherols reside in the outer layer of the LDL molecule, protecting the monolayer of phospholipids and the carotenoids are in the inner core protecting the cholesterylesters, and the progression of oxidation is likely to occur from the aqueous interface inwards, it seems reasonable to assign to a-tocopherol the rank of the front-line antioxidant. In vivo, the LDL will also interact with the plasma water-soluble antioxidants in the circulation, not in the artery wall, as mentioned above. 

---