Phospholipids lyso phosphatidylcholine

Glycerophospholipids contain a glycerol skeleton to which two fatty acids are esterified saturated fatty acids occupy mostly sn-position 1, whereas unsaturated fatty acids are mainly present on sn-position 2. The third hydroxyl is linked to a phosphate group to which an organic base is mostly esterified (Fig. 1). The most important components of soybean lecithin are phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylinositol (PI). Phosphatidic acid (PA) may become important due to the presence of phospholipase D this enzyme slowly converts PC into PA in vegetable lecithins. Phosphatidylserine (PS), phosphatidylglycerol (PG), and lyso-phosphatidylcholine (LPC) are known as minor components lysophospholipids contain only one acyl group per molecule. Besides, ether phospholipids occur in which one or both fatty acyl... 

Abbreviations APCI Atmospheric Pressure Chemical Ionization DAG Diacyl-glycerols DE Delayed Extraction DHB 2,5-Dihydroxybenzoic Acid El Electron Impact ESI Electrospray Ionisation FACS Fluorescence-activated cell sorting GC Gas Chromatography HDL High Density Lipoprotein HPLC High-Performance Liquid Chromatography IR Infrared LDL Low Density Lipoprotein LOD Level of Detection LOQ Level of Quantification LPC Lyso-Phosphatidylcholine LPL Lyso-Phospholipid MALDI Matrix-... 

Choline-containing phospholipids (phosphatidylcholine and lyso-phosphatidylcholine)... 

Figure 2.4. Isocratic elution of rat liver phospholipids from a column of silica gel with hexane-isopropanol-25 mM phosphate buffer-ethanol-acetic acid (367 490 62 100 0.6 by volume) as mobile phase at a flow-rate of 0.5 mL/min for the first 60 minutes then of 1 mL/min, and with spectrophotometric detection at 205 nm [694]. (Reproduced by kind permission of the authors and of the Journal of Lipid Research, and redrawn from the original publication). Abbreviations NL, neutral lipids PE, phosphatidylethanolamine PA, phosphatidic acid PI, phosphatidylinositol PS, phosphatidylserine DPG, diphosphatidylglycerol PC, phosphatidylcholine SPH, sphingomyelin LPC, lyso- phosphatidylcholine XI, X2, X3 and X4, unidentified lipids.

Lysophospholipids have been found in butter serum by Cho et al. (1977). They characterized the sn-1 and -2 lysophosphatidylcholines and phosphatidylethanolamines. It is not known if these compounds are products of degradation or remnants of biosynthesis. Cho et al. (1977) searched for, but did not find, another possible product of enzymatic degradation of milk, phosphatidic acid. Phosphatidic acid can be formed by the action of phospholipase D on phosphatidylcholine, for example, but this enzymatic activity was not detected. The compound is also an important intermediate in the biosynthesis of lipids, but the concentration in tissue is always very low. The amount is also low in milk. Cho et al. (1977) found 1.2 and 0.9 (percent of total lipid P) of the lyso compounds above. The quantities of the other phospholipids were phosphatidylethanolamine, 27.3 -choline, 29.1 -serine, 13.4 -inositol, 2.5 and sphingomyelin, 25.6. 

In lipoproteins, one finds essentially the same types of lipids but with somewhat different concentrations. In order of decreasing numbers, low density lipoproteins contain (2) mainly cholesteryl esters, (unesterified) cholesterol, phosphatidylcholines, SM, triglycerides, and lyso-PC, and smaller numbers of PE, PI, and ceramide. In HDLs, one finds the same lipid types but in a different order, as HDLs are abundant in phospholipids and are complemented by cholesterol esters, cholesterol, and triglycerides. 

Most of the lipids of the neutral fraction were eluted at the solvent front when the chloroform/methanol/water solvent system, which is suitable for the separation of the acidic fraction, was used. We then tried solvent systems which can separate more hydrophobic lipids. Using the hexane/ ethyl acetate/ethanol/0.1% aqueous ammonia solvent system, we could separate phospholipids (Fig. 2B) and glycolipids (data not shown). A 5-mg amount of a neutral fraction from human brain lipids was applied to TC-CCC by using hexane/ethyl acetate/ethanol/0.1% aqueous ammonia (5 5 5 4). Phosphatidylcholine (PC), sphingomyelin (SPM), and lysophosphatidylcholine (lysoPC) were successively eluted. Phosphatidylethanolamine (PE) and lyso-phosphatidylethanolamine (lysoPE) and other minor phospholipid components were retained as the column contents with this solvent system. Cerebroside (fr. 28/36) and some... 

A phospholipid monolayer in the surface is consistent with the current model that LD are formed by TAG deposition between the two leaflets of the ER membrane and may remain connected to it [144, 145 see below]. Distribution of acyl-CoA cholesterol acyltransferase-1, a major enzyme that synthesizes cholesterylester, in the entire ER [148] seems to indicate that LD may bud anywhere along the membrane. However, Cap-LC/ESI mass spectrometry showed that FA moieties of phosphatidylcholine and lyso-phosphatidylchohne in LD are distinct from those in the rough ER [149]. The results do rule out the generation of the LD surface generated from the ER membrane but indicate that the former is a highly differentiated domain. Mature LD might be independent of the ER. Alternatively, the LD may be connected to the ER, but some molecular mechanism may demarcate the LD surface from the bulk ER membrane as postulated for other ER domains [150]. Whatever is true, TAG synthesized in wide areas of the ER do not deposit indiscriminately but are concentrated to loci specialized to make LD. ADRP or other LD-associated proteins may be involved (see below). 

Lysophosphatidylcholine is a frequent product of oxidized phospholipid hydrolysis and shows structural similarities to its diacyl counterparts containing a short acyl chain in sn-2 position. Therefore, its cellular activities deserve particular attention, especially in the context of its cytotoxicity. The effects of phospholipid oxidation products and lyso-PC depend not only on their concentration but also on the cell type. Lyso-PC containing a long acyl chain in sn- position (e.g. C16 0, C18 0) is an amphiphilic phospholipid that is generated by phospholipase-catalyzed hydrolysis of phosphatidylcholine or extensive oxidation leading to loss of the entire sn-2 acyl chain. Its critical micellar concentration (CMC) is around 50 pM. It is easily taken up into lipid membranes and increases their fluidities . Above the CMC it forms micelles that destroy membrane integrity also by removal of proteins as shown in erythrocytes (Bierbaum et al., 1979 Colics and Chisholm, 2000). Lyso-PC exerts apoptotic effects in rVSMCs at concentrations below its CMC and induces necrotic cell death at concentrations above its CMC (Hsieh et al.,... 

High-performance health beneficial emulsifier (i.e., the DHA-bound lysophos-pholipid) can be prepared from squid meal phospholipid because squid meal phospholipid contains DHA exclusively in position sn-2 (Hosokawa 1996). For this reason, if we eliminate the fatty acid moiety in the sn-1 position by applying position 1,3-specific lipase, or phospholipase Aj, we can obtain the sn-2 DHA-bound lyso-phospholipid. As a substrate for the desired reaction, squid meal phosphatidylcholine (PC) is the most useful so far. 

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