Phosphatidylcholine homogenate

When liposomes are prepared from a molecular mixture of lipid components it is important that all lipids be homogeneously dissolved in an organic solvent in order to obteiin bilayers with evenly distributed lipids after hydration. For example, the solubilities of phosphatidylcholine and cholesterol in chloroform are similar their solubility in benzene differs. Upon removal of benzene from the lipid solution an inhomogeneous lipid film is formed on the glass wall and... 

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.

Figure 1 Experimentally determined values of ko obtained employing 3-methylindole as the quencher in homogeneous solvents, plotted as a function of the wavelength of maximum fluorescence intensity (data from Ref. 14). kap values determined in DODAC LUVs ( ) and in dipalmitoyl phosphatidylcholine (DPPC) LUVs (A) have been included. Also are included the experimentally determined value of kap in sodium dodecyl sulfate micelles ( ) and the value of kQ estimated from Eq. (21) ( ).

The lipidome profile of mice liver homogenates of free cholesterol, low cholesterol, and high cholesterol diets showed the influence between dietary cholesterol intake and atherosclerosis (17). To get individual metabolite fingerprints, they measured near 300 metabolites such as di- and triglycerides, phosphatidylcholines, LPCs, and cholesterol esters in plasma samples by LC-MS/MS. It was observed that when dietary cholesterol intake was increased, the liver compensated for elevations in plasma cholesterol by adjusting metabolic and transport processes related to lipid metabolism, which... 

Gergel D, Misik V, Ondrias K (1992) Effect of cisplatin, carbo-platin and stobadine on lipid peroxidation of kidney homogenate and phosphatidylcholine liposomes. Physiol Res 41 129-134... 

Ohtsuru et al. (25) have recently investigated the behavior of phosphatidylcholine in a model system that simulated soy milk. They used spin-labelled phosphatidylcholine (PC ) synthesized from egg lysolecithin and 12-nitroxide stearic acid anhydride. The ESR spectrum of a mixture of PC (250 yg) and native soy protein (20 mg) homogenized in water by sonication resembled that observed for PC alone before sonication. However, when PC (250 yg) was sonicated in the presence of heat-denatured soy protein (20 mg), splitting of the ESR signal occurred. On this basis, they postulated the existence of two phases PC making up a fluid lamella phase and PC immobilized probably due to the hydrophobic interaction with the denatured protein. In a study of a soy-milk model, Ohtsuru et al. (25) reported that a ternary protein-oil-PC complex occurred when the three materials were subjected to sonication under the proper condition. Based on data from the ESR study, a schematic model has been proposed for the reversible formation-deformation of the ternary complex in soy milk (Figure 2). 

Liposomes made of pure phospholipids will not form at temperatures below T of the phospholipid. This temperature requirement is reduced to some extent, but not eliminated, by the addition of cholesterol (17). In some cases, it is recommended that liposome preparation be carried out at temperatures well above T of the vesicles. For instance, in the case of vesicles con-taining dipalmitoyl phosphatidylcholine (DPPC, T = 41°C), it has been suggested that the liposome preparation procedure be carried out at 10°C higher than the T at 51°C (18, 19). This is in order to make sure that all the phospholipids are dissolved in the suspension medium homogenously and have sufficient flexibility to align themselves in the structure of lipid vesicles. Following termination of the preparation procedure, usually nanoliposomes are allowed to anneal and stabilize for certain periods of time (e.g. 30-60 min), at a temperature above T, before storage. 

Both circulating OxLDL and MDA-LDL have been measured in plasma by ELISA. Most commonly, the capture antibody is a monoclonal antibody against OxLDL or MDA-LDL and the detection antibody, a polyclonal or monoclonal antibody directed against apo B (El, S12, Tl). Usually, the capture antibody is developed against chemically modified MDA-LDL or OxLDL but antibody has been developed against homogenate of human arteriosclerotic plaque. This antibody reacted with oxidized phosphatidylcholines but not native LDL, or MDA-LDL (S12). 

PS, phosphatidylserine SM+I, sphingomyelin plus inositides PC, phosphatidylcholine PE, phosphatidylethanolamine WH, whole homogenate SR, sarcoplasmic reticulum. Values correspond to percent of total phospholipid. ... 

Since the precursor fatty acid (18 2) for 18 1 A formation is likely to be formed from oleoyl-phosphatidylcholine in the E.R. (Stymne and Appelqvist, 1978), it is reasonable to assume that the acetylenase is localized outside of the plastids, and perhaps in the E.R. itself. Therefore, microsomal preparations from developing cotyledons of Crepis alpina seeds were tested for their ability to convert [ " C]18 2 into [ C] 18 1 A. Microsomes from homogenate prepared in the presence of high amount of NADH were active in converting [14C]18 2-CoA into [14C]18 1-A. 

Abstract The formation of phosphatidylcholine liposomes loaded with proanthocyanidins isolated from grape Vitis vinifera L.) seeds was studied. Using scanning electron microscopy it was determined that the type and the size of the liposomes depend on various factors proanthocyanidin concentration and homogenization conditions (time and intensity). Rheological investigations of liposome dispersions... 

Multilamellar dispersions of homogeneous phosphatidylcholines exhibit two reversible phase transitions. The major chain-melting transition is a sharp symmetrical first-order endothermic transition in the DSC thermogram. For a series of saturated phospholipids, the enthalpy of the main transition is a linear function of the transition temperature (Fig. 10) [94], and the extrapolation to zero enthalpy suggests that saturated phosphatidylcholines with hydrocarbon chains shorter than 12 carbon atoms cannot form stable bilayers. 

Marie-Pierre Krafft at the Institut Charles Sadron, Strasbourg, has studied the polymerization of hydrophobic monomers such as isodecylacrylate (ISODAC) in small rmil-amellar vesicles of perfluoroalkylated phosphatidylcholine (F-PC). The process was compared with that for polymerization of ISODAC in egg PC vesicles. In the case of F-PC vesicles the formed pol3mer was homogeneously distributed throughout the vesicles whereas for egg-PC, parachute polymerization was found to be operative. Ferro and Krafft have also studied the effect of addition of semi-fluorinated alkanes (C jH2 j+iC F2 +i, H jF ) such as HioFe on Ca -induced fusion and the rate of release of 5,6-carboxyfluorescein referred to as (CF) from the water cores of the vesicles. For HioFg, the rate of fusion was reduced by an order of magnitude, and there was a 40-fold decrease in the rate of release of CF, as compared with phosphatidylserine vesicles as a reference. 

A remarkable homogeneity was noted for maize and spinach proteins, studl in this work and for castor bean protein. Isolated by Yamada s group (Table) a value close to 9 kDa was found for the three proteins. Another common feature is the isoelectric point which is hig varying from 8.8 to 10.5 basic PLTP are also present In animal cells However, acidic PLTP have been also ound in one plant tissue (castor bean) and in various animal sources. Ml the basic PLTP from plants are non specific towards phospholipids . The three proteins are able to transfer phosphatidylcholine, phosphatldyllnosltol and phosphatidyl-ethanolamlne in addition, spinach and castor bean proteins transfer respectively phosphatidylglycerol and phosphatldlc acid. 

Norman HA, Pillai P, St John JB. In vitro desaturation of monogalactosyldiacylglycerol and phosphatidylcholine molecular species by chloroplasts homogenates. Phytochemistry 1991 30 2217-22. 

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