Phosphatidyl Choline Lecithin

A major advance in the understanding of the biosynthesis of the glycerophos-phatides was the discovery by Kennedy and Weiss (1956) of the role of nucleotides of cytosine in the biosynthesis of the glycerophosphatides. Cytidine 5 -triphosphate (CTP) was shown to be necessary for the incorporation of phosphorylcholine into lecithin by liver preparations. Similar observations have been reported for brain (McMubbay et al. 1957, Stbickland et al. 1963) and other tissues. The nucleotide requirement is specific for CTP, none of the other nucleoside 5 -triphosphates being active. Kennedy and Weiss (1956) showed that CTP combines with phosphorylcholine to form the intermediate CDP-choline (IV) according to the equation  

CDP-choline has been characterized and synthesized (Kennedy 1956). It occurs in a number of tissues (Kennedy and Weiss 1956) including brain (Ansell and Bayliss 1961) and yeast (Bebgeb and Gimenez 1956). The properties of the enzyme phosphorylcholine-cytidyl transferase (CTP cholinephosphate cytidylyl-transferase EC 2.7.7.15) catalysing Reaction 11 have been studied by Bobken-HAGEN and Kennedy (1957), who showed that the enzyme readily catalyses the reverse reaction, i.e. the pyrophosphorolysis of CDP-choline, with the formation of phosphorylcholine and CTP. 

Kennedy and Weiss (1956) further showed that chicken Uver contains a second enz3moLe capable of forming lecithin (III) by the transfer of phosphorylcholine from CDP-choline (IV) to D-cx,j8-diglyceride (II) according to the equation  

The enzyme catalysing this reaction, phosphorylcholine-glyceride transferase (CDP-choline 1,2-diglyceride cholinephosphotransferase EC 2.7.S.2), was partially purified from liver by Weiss, Smith and Kennedy (1958), who showed that it catalyses the reverse reaction, i.e. the cytidylolysis of lecithin with the formation of CDP-choline and D-a,j8-diglyceride. 

The enzymes leading to the biosynthesis of lecithin by the pathways outlined above (Reactions 11 and 12) are not restricted to liver. They have been demonstrated in brain (Strickland et al. 1963) seminal vesicle (Williams-Ashman and Banks 1956) and intestinal mucosa (Gurr and Hubscher 1964). Experiments such as those of Miani and Bucciante (1958), in which inorganic P was administered to rats, and those of G0RANSSON (1964), in which labelled fatty acids were given, provided evidence that this pathway for the biosynthesis of lecithin is operative in vivo. 

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Choline Phosphatidyl choline (lecithins) Inositol Phosphatidyl inositol... 

Phosphatidyl choline (lecithin), phosphatidyl serine, phosphatidyl glycerol, phosphatidyl inositol, phosphatidic acid. 

A major approach to the treatment of AD has involved attempts to augment the cholinergic function of the brain. An early approach was the use of precursors of acetylcholine synthesis, such as choline chloride and phosphatidyl choline (lecithin). Although these supplements generally are well tolerated, randomized trials have failed to demonstrate any clinically significant efficacy. 

The classification of a phosphatidyl ester depends on the nature of the second alcohol esterified to the phosphoric acid. Some of the most important lipids in this class are phosphatidyl ethanolamine (cephalin), phosphatidyl serine, phosphatidyl choline (lecithin), phosphatidyl inositol, phosphatidyl glycerol, and diphosphatidyl glycerol (cardiolipin) (Figure 8.5). In each of these types of compounds, the nature of the fatty acids in the molecule can vary widely. All... 

L-a-Phosphatidyl choline (lecithin) phospholipid commonly found in plants, but much less so in microorganisms... 

Phosphatidyl Cholines (Lecithins) One of the most abundant glycerophospho-lipids in any tissue is phosphatidyl chohne ... 

Flexible bilayers Double-chain surfactants with large head group areas, e.g. phosphatidyl choline (lecithin), dihexadecyl phosphate... 

Phosphatidyl choline (lecithin). Phosphatidyl serine. Phosphatidyl glycerol. Phosphatidyl inositol, Phosphatidic acid, sphingomyelin, DGDG dihexadecyl phosphate, dialkyl dimethyl ammonium salts... 

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