Ethanolamine-phospholipids 2, 2

Triacylglycerols and some phosphoglycerols are synthesized by progressive acylation of glycerol 3-phosphate. The pathway bifurcates at phosphatidate, forming inositol phospholipids and cardiolipin on the one hand and triacylglycerol and choline and ethanolamine phospholipids on the other. 

In a typical spectrum, the peak at 524 represents the mass ion MH+ and mlz 482 represents the deacetylated derivative. Also an additional fragment of importance in use in structure studies is the mlz 184, which represents the 0-phosphocholine residue. These are the major fragments obtained from 1-0-hexadccyl-2-acetyl-.y -glycero-3-phosphocholine. Similar information can be derived from a similar derivative in which the acetyl group is replaced by an oleoyl residue. In this case the mass ion MH+ would be 746 and mlz 184 would represent the 0-phosphocholine group. If a linoleoyl (at sn-2), hexa-decyl (at rn-l)-substituted derivative were present, then a mass ion of 744 would be detected. With regard to the polar head groups, an ethanolamine phospholipid would yield on FAB an mlz 142, indicative of a protonated O-phosphoethanolamine. 

As emphasized, dietary fatty acids produced drastic modification of the molecular species of brain ethanolamine phospholipids. Hargreaves and Clandinin reported similar findings in the rat (Connor et al., 1997). Using argentation thin-layer chromatography (TLC), which is unable to resolve individual molecular species, they fed fish-oil or linseed-oil diets to rats, which resulted in an increased microsomal and synaptic membrane content of phosphatidylethanolamine species containing six double bonds, and a decrease in species containing five double bonds, compared with animals fed soy or safflower oil. 

Ansell Yes the lysosomes that we have obtained from brain tissue certainly do not contain any phospholipases that can attack ethanolamine phospholipids. I would not like to say at this point in the investigation that they do not contain phospholipases attacking choline lipids. 

The question of intermediate structures around a phase transition has caught particular attention in the case of the lamellar-to-inverted hexagonal transition of ethanolamine phospholipids, since this involves a major topological change (see Fig. 6). Inverted micellar structures were proposed as intermediates on the basis of P-NMR and electron microscopic results and also rationalized in a theoretical mechanism On the other hand, first results of time-resolved X-ray diffraction... 

Furthermore, OxPL were shown to modulate the activity of the platelet prothrombinase complex, a major contributor to overall thrombin formation. Platelet-dependent thrombin generation was induced by ethanolamine phospholipids (PE) present in oxidized LDL. It was shown that oxidation products of unsaturated diacyl-PE were mainly responsible for the increased prothrombinase activity and synthetic aldehyde-PE adducts largely reproduced the stimulation of the thrombin generation (Zieseniss et al. 2001). These data suggest that oxidized PE contribute to the prothrombotic phenotype by increasing prothrombinase activity in platelets. 

Gugiu, B, Mesaros, C, Sun, M, Gu, X, Crabb, J W, and Salomon, R G, Identification of oxidatively truncated ethanolamine phospholipids in retina and their generation from polyunsaturated phosphatidylethanolamines, Chem. Res. Toxicol. 19 (2006) 262-271. 

C. butyricum appears to regulate the stability of the bilayer arrangement of membranes by altering the ratio of ether versus acyl ethanolamine phospholipids in response to changes in the degree of lipid unsaturation of the membranes. Experiments with bacteria indicate that substitution of plasmenylethanolamine for phosphatidylethanolamine in biomembranes would have only small effects on lipid melting transitions, whereas the tendency to form non-lamellar lipid structures would be significantly increased. 

Moesgaard, B., Petersen, G., Jaroszewski, J.W., and Hansen, H.S. (2000) Age dependent accumulation of N-acyl-ethanolamine phospholipids in ischemic rat brain. A P NMR and enzyme activity study. Journal of Lipid Research 41 985-990. 

Natarajan, V., Reddy, RV., Schmid, PC., and Schmid, H.H.O. (1982) Al-Acylation of ethanolamine phospholipids in canine myocardium, Biochimica et Biophysica Acta 1982 712 342-355. 

Moesgaard B, Petersen G, Mortensen SA, and Hansen HS. (2002) Substantial species differences in relation to formation and degradation of iV-acyl-ethanolamine phospholipids in heart tissue an enzyme activity study. Comp Biochem Physiol B Biochem Mol Biol. 131 475-82. 

Approximately 30% of position sn-2 in human platelet phospholipids consists of arachidonate. Of course, the percentage of arachidonate varies within the different phospholipids species and the amounts of the different species of phospholipid vary in the platelet. This is illustrated in Table 1.1. which shows that sphingomyelin contains essentially t-o arachidonic acid while ethanolamine-phospholipids contain the most arachidonic acid. Although phosphatidylinositol is the phospholipid species that is most enriched in arachidonic acid, its contribution to the total content of arachidonate in blood platelets is smalP. ... 

Since ouabain decreased cation transport and yet stimulated phosphate exchange in phosphatidic acid over a short period, any relationship of this particular lipid to cation transport would be difficult to explain. Digitoxin also enhanced the uptake of labeled phosphate into the phospholipids of rat heart in vivo (Marinetti et al., 1%1) the effect was greatest with ethanolamine phospholipids, but in these experiments the possibility of an increased permeability of the tissue to phosphate was not eliminated. Recent studies have strongly suggested that ouabain inhibits the sodium- and potassimn-activated adenosinetriphosphatase (Chamock and Post, 1963). It may well do this by specifically inhibiting the potassium-dependent phosphorolysis reaction which leads to the release of orthophosphate (see also, McIIwain, 1963). 

Glycerol 1,2-0-hexadecylidene-3-pbos-phorylethanolamine (cyclic acetal ethanolamine phospholipid) 0.05-0.075... 

Figs. 4,5,6 show the percent distribution of labelled fatty acids incorporated into the lipid fractions under study. While the 11-11-stearic acid (Fig. 4) is preferentially incorporated in the triacyglycerol fraction of control tissue, a remarkable increase in the percent radioactivity in the ethanolamine phospholipid fraction from tumoral tissue was found. 

Natarajan V, Schmid PC, Reddy PV, Schmid HHO. Catabolism of N-acyl-ethanolamine phospholipids by dog brain preparations. J Neurochem 1984 42 1613-1619. 

Mammals synthesize phosphatidylserine (PS) in a calcium ion-dependent reaction involving aminoalcohol exchange (Figure 25.21). The enzyme catalyzing this reaction is associated with the endoplasmic reticulum and will accept phosphatidylethanolamine (PE) and other phospholipid substrates. A mitochondrial PS decarboxylase can subsequently convert PS to PE. No other pathway converting serine to ethanolamine has been found. 

These compounds constimte as much as 10% of the phospholipids of brain and muscle. StmcmraUy, the plasmalogens resemble phosphatidylethanolamine but possess an ether link on the sn- carbon instead of the ester link found in acylglycerols. Typically, the alkyl radical is an unsamrated alcohol (Figure 14-10). In some instances, choline, serine, or inositol may be sub-stimted for ethanolamine. 

Figure 24-2. Biosynthesis of triaq/lglycerol and phospholipids. ( , Monoacylglycerol pathway (D, glycerol phosphate pathway.) Phosphatidylethanolamine may be formed from ethanolamine by a pathway similar to that shown for the formation of phosphatidylcholine from choline.

In multiple sclerosis, which is a demyelinating disease, there is loss of both phospholipids (particularly ethanolamine plasmalogen) and of sphingolipids from white matter. Thus, the lipid composition of white matter resembles that of gray matter. The cerebrospinal fluid shows raised phospholipid levels. 

Recently in our group, model membrane permeation barriers have been constructed with concentrated phospholipid solutions, 10-74% wt/vol soy lecithin (approximate %w/w lipid composition 24% PC, 18% PE, 12% PI cf. Table 3.1) in dodecane, supported on high-porosity, hydrophobic microfilters. This newly formulated lipid has a net negative charge at pH 7.4, which further increases above pH 8, as the ethanolamine groups deionize. Also tested were 10% wt/vol egg lecithin lipid solutions in dodecane (approximate composition 73% PC, 11% PE,... 

This process probably occurs in vivo because the adduct of ethanolamine and p-hydroxyphe-nylacetaldehyde is abundant in the phospholipids of LDL exposed to activated neutrophils and tyrosine. 

---