Phosphatidylethanolamine quantitation

Koryta et al. [48] first stressed the relevance of adsorbed phospholipid monolayers at the ITIES for clarification of biological membrane phenomena. Girault and Schiffrin [49] first attempted to characterize quantitatively the monolayers of phosphatidylcholine and phos-phatidylethanolamine at the ideally polarized water-1,2-dichloroethane interface with electrocapillary measurements. The results obtained indicate the importance of the surface pH in the ionization of the amino group of phosphatidylethanolamine. Kakiuchi et al. [50] used the video-image method to study the conditions for obtaining electrocapillary curves of the dilauroylphosphatidylcholine monolayer formed on the ideally polarized water-nitrobenzene interface. This phospholipid was found to lower markedly the surface tension by forming a stable monolayer when the interface was polarized so that the aqueous phase had a negative potential with respect to the nitrobenzene phase [50,51] (cf. Fig. 5). 

Mammalian ceU membranes consists of a variety of lipids. The phospholipids, phosphatidylcholine (PC) and phosphatidylethanolamine (PE) are quantitatively the most important lipids in cellular membranes. PC and PE are synthesized via different pathways in mammalian cells. 

The three quantitatively important phosphoglycerides are phosphatidylchohne, phosphatidylethanolamine and (ii) phosphatidylinositol. 

As before, the phosphatidylethanolamine sample in chloroform-methanol (1 10, v/v) is treated with 0.5 N NaOH in methanol for 20 min at room temperature. The reaction is stopped by the addition of an equivalent amount of 6 N HCI. Subsequent extraction of the mixture by the Bligh-Dyer method will ultimately yield a chloroform soluble fraction (containing the methyl esters) and a water-soluble phase (containing the glycerophosphoethanola-mine). Under these conditions, the reaction is usually quantitative this can be... 

In blood, phosphatidylcholine is quantitatively the most important phospholipid. Sphingomyelin is present in varying amounts in perhaps all of the animal organs, most of it in the soft organs, and to a lesser degree in skeletal muscles and eggs (4). Total blood contains about 0.2% to 0.3% phospholipids. In plasma and serum, phosphatidylcholine predominates, whereas in corpuscles, phosphatidylethanolamine and sphingomyelin constitute the bulk of phospholipids. Most workers have found... 

The fatty acid composition of muscle lipids may show quantitative alterations in diseased muscle. Thus lecithin isolated from human dystrophic muscle had an increased amount of oleic but diminished linoleic acid (Tl). Changes have been recorded also in the fatty acid composition of lecithin from denervated muscle (PI). Recently it has been reported (K16) that the fatty acid pattern of muscle phosphatides from patients with the autosomal dominant form of myotonia congenita differed markedly from that of the autosomal recessive form and from the normal. Tani and his co-workers (F7) have made a detailed study of the phospholipids of normal and dystrophic mouse tissues. In normal mice phosphatidylcholine and phosphatidylethanolamine from skeletal and heart muscles had a very high content of 20-22-carbon polyunsaturated acids, in comparison with those for other tissues the most abundant was docosahexaenoic acid. In dystrophic mice there was a sharp decrease in the proportion of docosahexaenoic acid in the phosphoglycerides from skeletal and heart muscles, suggesting the likelihood of important alterations in muscle membranes. Somewhat similar studies have been reported by Owens (05), who also observed a fall in the proportion of docosahexaenoic acid, mainly in the phosphatidylcholine -j- choline plasmalogen fraction. 

The inclusion of phosphoric acid in the mobile phase increases the potential for error in subsequent quantitation by lipid phosphorus determinations and has been replaced with a mobile phase containing acetonitrile-methanol-sulphuric acid (100 3 0.05) to provide resolution of phosphatidylinositol, phosphatidylserine, phosphatidyl-ethanolamine, phosphatidylcholine, lysophosphatidylcholine and sphingomyelin (Kaduce et al., 1983). The authors reported that a reduction in the sulphuric acid content of the mobile phase caused a broadening of the eluted peaks and an increase in the retention of phosphatidylserine, phosphatidylethanolamine and phosphatidylcholine, while if omitted, these components did not elute. It was also noted that if the methanol content of the mobile phase was increased then the retention times of all the phospholipids were decreased. Samples were therefore injected in chloroform-diethyl ether (1 1) to avoid altering the concentration of methanol in the mobile phase. 

P NMR spectra can reflect the energetic status of cells (quantitation of ATP, PCr, Pi) the chemical shift of Pi depends on the intracellular pH, which can be measured in this way [35]. By use of C-labelled substrates, the kinetics of phosphatidylethanolamine synthesis has been studied by C NMR spectroscopy of extracts of lymphomatous mouse liver following the administration of C2-ethanoloamine [36]. 

Wang, M., Kim, G.H., Wei, F., Chen, H., Altarejos, J. and Han, X. (2015) Improved method for quantitative analysis of methylated phosphatidylethanolamine species and its application for analysis of diabetic-mouse liver samples. Anal. Bioanal. Chem. 407, 5021-5032. 

Phosphatidylserine has already been mentioned in its connection as a precursor for phosphatidylethanolamine. It is a quantitively minor lipid in animal tissues where it appears to be formed by Ca -dependent base-exchange on pre-formed microsomal (probably endoplasmic reticulum) lipids. The enzyme is probably the same as that responsible for the exchange of choline and ethanolamine as well. 

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