Phosphatide, phosphatidic acid, phosphatidylcholine, phosphatidylethanolamine phosphatidylinositol, phosphatidylserine

Abbreviations C = chloroform M = methanol DPG = diphosphatidylglycerol (cardio-lipin) PA = phosphatidic acid PE = phosphatidylethanolamine PS = phosphatidylserine PI = phosphatidylinositol PC = phosphatidylcholine. 

Figure 9.1 Structure of the most common phospholipids. PA = phosphatidic acid PE = phosphatidylethanolamine PC = phosphatidylcholine PS = phosphatidylserine PG = phos-phatidylglycerol PI = phosphatidylinositol.

It can be seen from Figure 1 that the choline-containing phospholipids, phosphatidylcholine and sphingomyelin are localized predominantly in the outer monolayer of the plasma membrane. The aminophospholipids, conprising phosphatidylethanolamine and phosphatidylserine, by contrast, are enriched in the cytoplasmic leaflet of the membrane (Bretcher, 1972b Rothman and Lenard, 1977 Op den Kamp, 1979). The transmembrane distribution of the minor membrane lipid components has been determined by reaction with lipid-specific antibodies (Gascard et al, 1991) and lipid hydrolases (Biitikofer et al, 1990). Such studies have shown that phosphatidic acid, phosphatidylinositol and phosphatidylinositol-4,5-fc -phosphate all resemble phosphatidylethanolamine in that about 80% of the phospholipids are localized in the cytoplasmic leaflet of the membrane. 

Phosphatidic acid Phosphatidylethanolamine Phosphatidylcholine Occithin) Phosphatidylserine Phosphatidylinositol... 

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... 

Fig. 20.3. Schematic representation of the main pathways in the lipid metabolism of parasitic flatworms. Boxed substrates are supplied by the host. Pathways present in mammalian systems but absent in parasitic flatworms are shown by open arrows. Abbreviations DAG, diacylglycerol CDP-DAG, cytidine diphosphodiacylglycerol Farnesyl PP, farnesyl pyrophosphate Geranyl PP, geranylpyrophosphate Geranylgeranyl PP, geranylgeranylpyrophosphate FlMG-CoA, hydroxymethylglutaryl-CoA TAG, triacylglycerol PA, phosphatidic acid PC, phosphatidylcholine PE, phosphatidylethanolamine PI, phosphatidylinositol PS, phosphatidylserine.

PHOSPHATIDES Phosphatidylcholine Phosphatidylethanolamine Phosphatidyl-N-acetylethanolamine Phosphatidylserine Phosphatidylinositol Phosphatidylglycerol Phosphatidic acid... 

Abbreviations PC - phosphatidylcholine PE - phosphatidylethanolamine PI — phosphatidylinositol PA - phosphatidic acid PS - phosphatidylserine. 

Fig. 1. Phospholipid biosynthetic pathways in animal cells. The abbreviations are DHAP, dihydroxyacetone phosphate G-3-P, glycerol-3-phosphate PA, phosphatidic acid DG, diacylglycerol CDP-DG, cytidine diphosphodiacylglycerol PI, phosphatidylinositol PG, phosphatidylglycerol PG-P, phosphatidylglycerol phosphate DPG, diphosphatidylglycerol PP, phosphatidic acid phosphatase PE, phosphatidylethanolamine PC phosphatidylcholine PEMT, phosphatidylethanolamine A-methyltransferase CT, CTP phosphocholine cytidylyltransferase PS, phosphatidylserine CK/EK, choline/ethanolamine kinase CPT, CDP-choline 1,...

See also Molecular Structures and Properties of Lipids, Phosphatidic Acid, Cardiolipin, Phosphatidylserine, Phosphatidylethanolamine, Phosphatidylglycerol, Phosphatidylcholine, CDP-Diacylglycerol, Phosphatidylglycerol-3-Phosphate, Phosphatidylinositol, Lung Surfactant, Sphingolipids, Glycosphingolipids,... 

The lipid classes of hazelnut oil include triacylglycerols (TAG) as nonpolar lipids (98.4%) and glucolipids (1.4%) and phosphoUpids (<0.2%) [phosphatidylcholine (PC) and phosphatidylinositol (PI)] as polar lipids [116]. The 18 lo)9 is dominant in the nonpolar lipid class (TAG), whereas 16 0, 18 0, and 18 2o)6 are most predominant in the polar Upid class in hazelnut oil. Recently, Alasalvar et al. [117] examined lipid class composition of Tombul hazelnut oil and found that it contained 98.8% of nonpolar and 1.2% of polar constituents. The main nonpolar lipid class in hazelnut oil is TAG, contributing nearly 100% to the total amount PC, phosphatidylethanolamine (PE), and PI are main polar Upids, contributing 56.4%, 30.8%, and 11.7% to the total polar lipids, respectively. Similar results were reported by Parcerisa et al. [105]. More recently, Miraliakbari and Shahidi [216] examined the lipid classes in tree nut oils that included TAG, sterols and sterol esters, phospholipids, and sphingoUpids. Hazelnut oil contained TAG, sterols, sterol esters, phosphatidylserine (PS), PC, PI, phosphatidic acid, and sphingoUpids. 

Phosphatidylcholine (PC) Phosphatidylethanolamine(PE) Diphosphatidylglycerol (DPG) Phosphatidylinositol (PI) Phosphatidylserine (PS) Sphingomyelin (SP) Phosphatidylglycerol (PC) Lysophosphatidylcholine (LPC) Phosphatidic acid (PA)... 

Figure 4.21 NMR spectrum of soybean lecithin. LPA = lyso-phosphatidic acid PA = phosphatidic acid PG = phosphatidylglycerol LPE = lyso-phosphatidylethanolamine DPG = diphosphatidylglycerol (or sphingomyelin SPH) APE = A-acyl-phosphatidylethanolamine PE = phosphatidylethanol-amine PS = phosphatidylserine LPC = lyso-phosphatidylcholine PI = phosphatidylinositol PC = phosphatidylcholine. Instrument details are given in text,...

Phospholipids. Phospholipids are fats in which glycerol is esterified with two fatty acids and a phosphoric acid. Such monophosphate esters are called phosphatidic acids (PAs). Most naturally occurring phospholipids contain one saturated and one unsaturated fatty acid. Free PAs are rare in nature. If found one may suspect them to be a degradation product from the hydrolysis of the more common phospholipids. The most common phospholipids are phosphatidylcholine (PC), phosphatidylethanolamine (PE), phos-phatidylglycerol (PG), phosphatidylinositol (PI) and phosphatidylserine (PS) (Fig. 9.1). 

Figure 35.11 Phosphatidic acid. This is the parent molecule of the phospholipids. Like triacylglycerol, it has a glycerol backbone but instead comprises two fatty acyl groups and one phosphate group. When this phosphate reacts with OH groups of compounds such as choline, ethanolamine, serine or inositol, phospholipids are formed known as phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol (Chapter 36).

The parent molecule of the phospholipid family is phosphatidic acid (Fig. 36.1). It consists of a glycerol backbone to which are esterified two fatty acyl molecules (palmitic acid is shown here) and phosphoric acid. The latter produces a phosphate which is free to react with the hydroxyl groups of serine, ethanolamine, choline or inositol to form phosphatidylserine, phosphatidylethanolamine, phosphatidylcholine or phosphatidylinositol, respectively. 

PC, Phosphatidylcholine PE, phosphatidylethanolamine PGP, diphosphatidylglycerol PA, phosphatidic acid PI, phosphatidylinositol PS, phosphatidylserine PG, phosphatidyl-glycerol. 

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.

Abbreviations DAG, diacylglycerol MAG, monoacylglycerol TAG, triacylglycerol NGSL, neutral glycosphingolipids PA, phosphatidic acid PC, phosphatidylcholine PE, phosphatidylethanolamine PG, phosphatidylglycerol PI, phosphatidylinositol PS, phosphatidylserine SM, sphingomyelin. See the text for other details. 

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