Choline phosphoglycerides, fatty acid

The different phosphoglycerides are often named by placing the constituent attached to the phosphate group after phosphatidyl , e.g. phosphatidyl choline (3-in-phosphatidylcholine or l,2-diacyl-sn-glycero-3-phosphoryl-choline). There are many phosphoglycerides because of the possible variation in the fatty acid chains, and when the full chemical structure is known, it should be used (e.g. l-palmitoyl-2-oleoyl-phosphatidylcholine). Nomenclature that entails the use of the DL system should be avoided. 

The complex lipids in milk fat are comprised of the phosphoglycerides, phosphatidyl choline, phosphatidyl serine, phosphatidyl ethanolamine, phosphatidylinositol and plasmalogens. Also, the non-glyceride phospholipid, sphingomyelin, occurs in important amounts (Jensen, 2002). Bitman and Wood (1990) described the distribution of phospholipid classes in bovine milk and their fatty acid composition. The phospholipids comprise about 1% and cholesterol 0.4—0.5% of the total milk fat. These occur almost completely in the milk fat globule membrane. 

Phosphoglycerides (the major phospholipids) contain glycerol, fatty acids, and phosphate. The phosphate is esterified to choline, serine, ethanolamine, or inositol. 

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. 

Martinez M. Ballabriga A, Gil-Gibernau JJ. Lipids of the developing human retina I. Total fatty acids, plasmologens, and fatty acid compostition of ethanolamine and choline phosphoglycerides. J Neurosci Res 1988- 20 484-490. 

Phospholipids, or phosphoglycerides, are amphipathic compounds that are used to make cell membranes, generate second messengers, and store fatty acids for use in the generation of prostaglandins. They can be synthesized from phosphatidate, an intermediate in triglyceride synthesis. Two common phospholipids, phosphatidyl choline and phosphatidyl inositol, are shown below (4). 

Phosphoglycerides consist of glycerol esterified to two fatty acids and phosphoric acid. The phosphoric acid is further esterified to choline (in the lecithins) and to etha-nolamine or serine (in the cephaUns). The phosphoglycerides are particularly important in membrane formation. 

Lipotropic substances compounds directly or indirectly involved in fat metabolism, which can prevent or correct fatty degeneration of the liver. They serve as substrates of phosphatide biosynthesis, or contribute (e.g. by methylation) to the synthesis of these substrates. Thus choline and any substance capable of contributing methyl groups for choline synthesis (e.g. methionine) are L.s. Liver is the major site of synthesis of plasma phosphoglycerides when the availability of choline is restricted, the rate of phosphatidylcholine synthesis decreases, and the rate of removal of fatty acids from the liver falls below normal. If the rate of supply of fatty acids (free and esterified) to the liver remains normal, the resulting accumulation of fat gives rise to the condition of fatty liver, or fatty degeneration of the liver. 

Phosphoglycerides are hydrolysed by naturally occurring enzymes, the phospholipases, which specifically cleave certain bonds within the molecule to release fatty acids, the phosphate ester, the alcohol and glycerol. The release of choline, when followed by further oxidative breakdown, has been considered to be responsible for the development of fishy taints by the release of the trimethyl amine group or its oxide currently these taints are considered to be the result of fat oxidation and not of lecithin breakdown. 

Another class of glycerides are those substances in which one of the fatty acid groups has been replaced by a phosphoric acid residue the phospholipids, or more accurately, the phosphoglycerides. The phosphate group is almost always further esterified, usually with a biological amino alcohol, such as choline (the lecithins) or ethanolamine (the cephalins) ... 

Lecithin is a phosphoglyceride (phosphatide) natural product isolated commercially from soybean oil and, in much lower quantity, from egg yolks. The terminology is somewhat confused for historical reasons (7). While the term lecithin is sometimes used synonymously with a-phosphatidyl choline, it more correctly denotes a crude mixture also containing P-phosphatidyl choline and phosphatidyl esters of other compounds, chiefly ethanolamine, inositol, and serine. (While phosphatidyl choline and phosphatidyl ethano-lamine are amphoteric, phosphatidyl inositol and phosphatidyl serine are anionic.) For soybean lecithin, R and R represent C16 saturated fatty acid and Cjg saturated and unsaturated... 

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