Lipids ternary

FIG. 1 Self-assembled structures in amphiphilic systems micellar structures (a) and (b) exist in aqueous solution as well as in ternary oil/water/amphiphile mixtures. In the latter case, they are swollen by the oil on the hydrophobic (tail) side. Monolayers (c) separate water from oil domains in ternary systems. Lipids in water tend to form bilayers (d) rather than micelles, since their hydrophobic block (two chains) is so compact and bulky, compared to the head group, that they cannot easily pack into a sphere [4]. At small concentrations, bilayers often close up to form vesicles (e). Some surfactants also form cyhndrical (wormlike) micelles (not shown). 

Protein 4.1, a globular protein, binds tightly to the tail end of spectrin, near the actin-binding site of the latter, and thus is part of a protein 4.1-spectrin-actin ternary complex. Protein 4.1 also binds to the integral proteins, glycophorins A and C, thereby attaching the ternary complex to the membrane. In addition, protein 4.1 may interact with certain membrane phospholipids, thus connecting the lipid bilayer to the cytoskeleton. 

FIGURE 10.12 The mole ratio of carotenoid/phospholipid and carotenoid/total lipid (phospholipid + cholesterol) in raft domain (detergent-resistant membrane, DRM) and bulk domain (detergent-soluble membrane, DSM) isolated from membranes made of raft-forming mixture (equimolar ternary mixture of dioleoyl-PC (DOPC)/sphingomyelin/cholesterol) with 1 mol% lutein (LUT), zeaxanthin (ZEA), P-cryptoxanthin (P-CXT), or P-carotene (P-CAR). 

KP and v can, in contrast to kp, not be determined via the concentration gradient for binary and ternary mixed micelles, because for the calculation of the Nemstian distribution a constant CMC and an almost constant partial molar volume must be assumed. The calculation of aggregation constants of simple bile salt systems based on Eq. (4) yields similar results (Fig. 8b). Assuming the formation of several concurrent complexes, a brutto stability constant can be calculated. For each application of any tenside, suitable markers have to be found. The completeness of dissolution in the micellar phase is, among other parameters, dependent on the pH value and the ionic strength of the counterions. Therefore, the displacement method should be used, which is not dependent on the chemical solubilization properties of markers. For electrophoretic MACE studies, it is advantageous for the micellar constitution (structure of micelle, type of phase micellar or lamellar) to be known for the relevant range of concentrations (surfactant, lipids). 

Fontell K, Khan A, Lindstrom B, Maciejewska D, Puangngern S (1991) Phase-Equilibria and Structures in Ternary-Systems of a Cationic Surfactant (C16tabr or (C16ta)2so4), Alcohol, and Water. Colloid Polym Sci 269 727-742 Israelachvili JN, Mitchell DJ, Ninham BW (1977) Theory of Self-Assembly of Lipid Bilayers and Vesicles. Biochim Biophys Acta 470 185-201... 

Moreau used a ternary gradient including 0.04% triethylamine in water 23 different classes of both nonpolar and polar lipids, including glycolipids and phospholipids, were resolved within 1 hour (57). Besides NL, FFA, DPG, PE, PG, PI, PS, and PC, three major hopanoid classes were... 

An experimental complication is the difficulty in effecting molecular interaction between the components. The usual technique for preparing lipid-protein phases in an aqueous environment is to use components of opposite charge. This in turn means that the lipid should be added to the protein in order to obtain a homogeneous complex since a complex separates when a certain critical hydrophobicity is reached. If the precipitate is prepared in the opposite way, the composition of the complex can vary since initially the protein molecule can take up as many lipid molecules as its net charge, and this number can decrease successively with reduction in available lipid molecules. It is thus not possible to prepare lipid— protein—water mixtures, as in the case of other ternary systems, and to wait for equilibrium. Systems were prepared that consisted of lecithin-cardiolipin (L/CL) mixtures with (a) a hydrophobic protein, insulin, and with (b) a protein with high water solubility, bovine serum albumin (BSA). 

As an alternative to cationic lipids, the potential of anionic lipids for DNA delivery has been investigated. Because of their negative charge, DNA or siRNA molecules are very inefficiently entrapped by anionic lipids alone. In the presence of cations such as K+, Na+, or Ca2+, the complex formation of such anionic lipids and nucleic acids can be enhanced. The resulting ternary complexes of DNA, anionic lipids, and divalent calcium ions have been reported to transfect mammalian cell lines efficiently [33]. Despite this, there has only been limited progress with these anionic lipid DNA delivery systems, a fact that may be attributed, in part, to the poor association between DNA molecules and anionic lipids, caused by electrostatic repulsion between these negatively charged species. 

Fig. 5 (a) TE of DNA complexes of binary DOTAP/DOPC lipid mixtures (black circles). Their TE increases over several orders of magnitude with increasing molar fraction of monovalent DOTAP (lipid mixtures with constant <1>dotap = 0.3. Different symbol shapes correspond to different choi (cf. legend), (b) The TE of the DNA complexes of ternary DOTAP/DOPC/Chol lipid mixtures (empty circles) plotted against aM significantly deviates from the universal bell shaped curve observed for binary systems [21]. Reprinted with permission from [27]. Copyright 2009 American Chemical Society... 

Lipids can act as precursors of a variety of aliphatic carbonyls with objectionable flavors. Proteins interact with lipids as well. The interaction is primarily through hydrophobic bonding. Additionally, a type of polar interaction may be involved, particularly when phospholipids take part. In the case of soy milk, a ternary protein-oil-phosphatidylcholine complex probably occurs. 

Although studies of the thermotropic phase behavior of singlecomponent multilamellar phospholipid vesicles are necessary and valuable, these systems are not realistic models for biological membranes that normally contain at least several different types of phospholipids and a variety of fatty acyl chains. As a first step toward understanding the interactions of both the polar and apolar portions of different lipids in mixtures, DSC studies of various binary and ternary phospholipid systems have been carried out. Phase diagrams can be constructed by specifying the onset and completion temperatures for the phase transition of a series of mixtures and by an inspection of the shapes of the calorimetric traces. A comparison of the observed transition curves with the theoretical curves supports... 

The properties of lipid bilayers formed from mixtures of lipids are very relevant to the understanding of the lipid bilayers that form the basis of biological membranes. Detailed studies have been performed on bilayers formed from binary lipid mixtures, and some reports in the recent literature describe phase diagrams of lipid bilayers prepared from ternary mixtures that include cholesterol. Figure 4 (24-31) shows some phase diagrams of lipid bilayers formed from binary and ternary mixtures of lipids. The general observation is that lipids in a bilayer are not very... 

Figure 4 Some phase diagrams for lipid bilayers in excess water prepared from binary and ternary lipid mixtures, a) Multibilayer lipid vesicles prepared from binary mixtures of DMPC and DPPC (24) b) Multibilayer lipid vesicles prepared from binary mixtures of DMPC and DSPC [adapted by Reference (25) from data for perdeuterated lipids published by Knoll et al. (26)] c) Multibilayer lipid vesicles prepared from binary mixtures of diCi/.QPC and C22 oCi2 oPC (27) d) Multibilayer lipid vesicles prepared from binary mixtures of DMPC and cholesterol (28) e) Multibilayer lipid vesicles prepared from ternary mixtures of palmitoyl sphingomyelin, POPC, and cholesterol [adapted by Reference (29), from data published by De Almeida et al. (30)] Lipid bilayers prepared from ternary mixtures of DSPC, DOPC, and cholesterol (31).

Some very hydrophobic samples, e.g., lipids, are strongly retained and not eluted in an acceptable time even with pure methanol or acetonitrile as the mobile phase. Such samples are usually adequately resolved by normal-phase chromatography, but they can be often equally well or even better separated by non-aqueous reversed-phase (NARP) chromatography in mixed mobile phases containing a more polar (e.g.. acetonitrile or methanol) and a less polar (e.g., tetrahydrofuran. dichloromethane. methyl-r-butyI ether) organic solvent. Ternary non-aqueous mobile phases may contain even hexane or heptane. The retention decreases with increasing concentration of the less-polar... 

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