Mixture Of Lysophosphatidylcholine Research Articles

Equimolar mixtures of lysophosphatidylcholine and O-stearoylethanolamine form bilayers

Lysophosphatidylcholine, a product of phospholipase A2-mediated hydrolysis of phosphatidylcholine, exhibits membranolytic activity. Therefore, its intracellular levels are under rigid control in normal cells, but accumulate in tissues under stress, e.g., ischemic myocardium. O-Stearoylethanolamine, a structural isomer of N-stearoylethanolamine, a single-chain lipid with putative stress fighting ability, forms bilayer structure at 1 : 1 (mol/mol) mixture with lysophosphatidylcholine. This suggests that O-stearoylethanolamine can buffer the membranolytic effect of lysophosphatidylcholine, which may play a role in the stress-combating responses of organisms.

Isolation and identification of molecular species of phosphatidylcholine and lysophosphatidylcholine from jojoba seed meal (Simmondsia chinensis).

A mixture of lysophosphatidylcholine (LPC) and phosphatidylcholine (PC) has been isolated by column chromatography from a jojoba meal (Simmondsia chinensis) extract. The molecular species of both classes could be separated and isolated by C18 reversed phase HPLC. The two major compounds were identified by 1D and 2D (1)H and (13)C NMR, by MS, and by GC-MS as 1-oleoyl-3-lysophosphatidylcholine and 1,2-dioleoyl-3-phosphatidylcholine. Eight other molecular species of LPC and four other molecular species of PC could be assigned by comparison of the mass spectra of the isolated compounds with the spectra of the two major compounds. Complete characterization of the individual molecular species was achieved by GC and GC-MS analysis of the fatty acyl composition from the isolated compounds. The PC/LPC proportion in the phospholipid mixture from three different samples is 1.6 +/- 0.1. LPC is considered to be an important bioactive compound; the results of this study suggest further research for the evaluation of potential health benefits of jojoba meal phospholipids.

Vitamin D‐binding protein (group‐specific component) is the sole serum protein required for macrophage activation after treatment of peritoneal cells with lysophosphatidylcholine

In vitro treatment of mouse peritoneal cells with 1 micrograms lysophosphatidylcholine (lyso-Pc)/mL in serum free-0.1% egg albumin-supplemented RPMI 1640 medium for 30 min, followed by 3 h cultivation in a medium supplemented with human serum, resulted in a greatly enhanced Fc-receptor-mediated phagocytic activity of macrophages. Vitamin D-binding protein (group-specific component [Gc]) of alpha 2-globulin fraction was shown to be the sole serum glycoprotein required for the generation of a potent macrophage-activating factor. When a mixture of lysophosphatidylcholine (lyso-Pc)-treated nonadherent and adherent cells were cultured in a medium supplemented with a small amount of purified Gc protein (1 ng/mL), a greatly enhanced activation of macrophages was demonstrated. The generation of macrophage-activating factor from purified Gc protein was far more efficient than that from whole serum, indicating that a serum component is inhibitory to the activation process of macrophages. While three other major serum glycoproteins (alpha 2-macroglobulin, alpha 2-HS-glycoprotein and haptoglobin) were neither stimulatory nor inhibitory to lyso-Pc-primed macrophage activation, serum albumin (competitively with Gc protein) appeared to be inhibitory to the process of macrophage activation.

Structural simulation of free radical damage in a model membrane system: a small-angle X-ray diffraction study

Membrane injury is an important factor contributing to cellular death following environmental stress. Recent evidence suggests that in plants, changes in membrane phase properties after exposure to a lethal environmental stress may be a result of lipid deesterification mediated by free radicals. To test this hypothesis, the effects of primary free radicals, produced by the radiolysis of water in the absence of oxygen, upon the structure of a dipalmitoylphosphatidylcholine (DPPC) model membrane system were studied. Small-angle X-ray diffraction and differential scanning calorimetry were used to examine DPPC bilayers exposed to increasing doses of gamma radiation. The electron density distribution of the bilayer did not change with increasing irradiation, but the thickness of the water layer between adjacent bilayers increased significantly. The upper limit of the broadened gel to liquid-crystal transition was increased by 4 to 10 Cdeg by the radiation treatment. Compositional analysis of the DPPC bilayer after irradiation indicated that a substantial portion of the phospholipid had been deesterified. Lysophosphatidylcholine was not detected. The changes in structural properties of the bilayer were simulated when the sodium salt of palmitic acid was incorporated into the DPPC bilayers but not by the addition of the acid itself. A mixture of lysophosphatidylcholine, sodium palmitate and DPPC did not simulate the structural changes. The free radicals generated by irradiation promoted deesterification at both the 1 and 2 positions of the glycerol backbone of DPPC, and the resultant accumulation of fatty acid salt in the bilayer altered its structural properties.

Phospholipid-dependent assembly of mitochondrial ATPase complex

1. 1. Phosphatidylcholines of different acyl-chain composition and a preparation of ATPase complex depleted of phospholipids have been employed in order to evaluate the contribution of lipid bilayer to the assembly of this multisubunit component of mitochondrial membrane. 2. 2. At the minimal requirement for bilayer assembly (dinonanoylphosphatidylcholine, mixtures of lysophosphatidylcholine and phosphatidylcholine), fragments with oligomycin-insensitive ATPase activity are reconstituted. Conformational changes with dislocation of ATPase complex subunits may explain these results. 3. 3. At increased strength of acyl-chain interaction (dilauroylphosphatidylcholine and higher homologues), the damage to the ATPase complex is prevented but this is not sufficient to achieve functional restoration. Bilayers with a tendency to coalesce and fuse aggregate in large amounts with the complex and yield low ATPase reactivation. Bilayers of high stability yield complexes with physiological content of phospholipids and efficient ATPase activity. Transition between these two possibilities is found at sixteen carbon acyl-chains. Only at this chain length does the cholate dialysis procedure of reconstitution become feasible. 4. 4. It is concluded that a minimum of 16 carbon atoms in each chain are required to organize a bilayer structurable to maintain the ATPase complex conformation and to sustain the transmembrane position of the whole assembly.