Cephalin fatty acid

If an amphiphile, such as lysolecithin, is suspended in water, it forms micelles, whose three-dimensional shape is that of an inverted cone. The basis for this type of assembly is that the hydrophobic fatty acid tails will interact with each other and exclude water from their environment, whereas the hydrophilic phosphocholine section remains in contact with the aqueous environment. If lecithins, cephalins, or cardiolipins are suspended in water, they aggregate into... 

There are several problems requiring careful attention. Lysozyme has a tendency to form complexes with many substances [e.g., alkyl sulfates, fatty acids, aliphatic alcohols (Smith and Stocker, 1949), cephalins (Brusca and Patrono, 1960), and other proteins]. Of particular importance is its tendency to form complexes with transferrins [e.g., ovotrans-ferrin (Ehrenpreis and Warner, 1956)]. These interactions lead to difficulties in the isolation of lysozyme. Some recent workers have used fast protein liquid chromatography (FPLC) and high-performance liquid chromatography (HPLC) (e.g., Ekstrand and Bjorck, 1986). The resolution in these procedures may not always be satisfactory, and in HPLC pressure and solvent effects must be monitored carefully if the product is to be suitable for conformation and activity studies. 

Almost all body cells contain phospholipids. The common animal phospholipids are made of sphingomyelin, phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylinositol (PI), and other glycerol phospholipids of complex fatty acid composition. PC, formerly referred to as lecithin, PE, formerly referred to as cephalin, and PS are by far the most predominant phospholipids from most animal sources. As constituents of cell walls and active participants in metabolic processes, they appear to be essential to life (8). 

As the shortest carbon chain members, the polar lipids in lecithins are traditionally depicted in the sn-3 triacylglycerol position. The major polar lipids and fatty acids in deoiled lecithins from various oilseed species are presented in Tables 10 and 11, respectively (44, 45). In the trade, the term lecithin sometimes is used interchangeably with phosphatidylcholine, and cephalin is interchanged with phosphatidylethanolamine. 

Free Fatty Acids Phosphatides (lecithin/cephalin/ phosphatidic acid)... 

Phosphoglycerides such as lecithin and cephalin are closely related to fats. The glycerol backbone in these molecules is esterified to two fatty acids (one saturated and one unsaturated) and to one phosphate ester. Sphingolipids, another major class of phospholipids, have an amino alcohol such as sphingosinc for their backbone. These compounds are important constituents of cell membranes. 

Properties Yellowish, amorphous substance characteristic odor and taste. Insoluble in water and acetone soluble in chloroform and ether slightly soluble in alcohol. A group of phospholipids in which two fatty acids (Rt and R2) form ester linkages with the two hydroxyl groups of glycerophosphoric acid, and either ethanolamine or serine (Rj) forms an ester linkage with the phosphate group. Cephalins are therefore either phosphatidylethanolamine or phosphatidylserine. They are associated with lecithins found in brain tissue, nerve tissue, and egg yolk. 

Phosphatidylethanolamines, or cephalins (so-called because they were first obtained from brain tissue), can be synthesized by reactions analogous to those of de novo synthesis of phosphatidylcholine. Ethanolamine is first phosphorylated by ATP and ethanolamine kinase to phosphoethanolamine, which then reacts with CTP to form CDP-ethanolamine. CTPrphosphoethanolamine cytidylyltransferase is not located on the endoplasmic reticulum, nor do fatty acids activate it as they do the analogous enzyme of phosphatidylcholine synthesis. Finally, 1,2-diacylglycerol phosphoethanolamine transferase catalyses the reaction of diacylglycerol with CDP-ethanolamine to form phosphatidylethanolamine. 

Antonis (A3) has estimated phospholipids by a procedure for determining fatty acids. This technique requires a total serum extract and a phospholipid-free extract for the measurement of both total and free fatty acids, the difference between them being a measure of the phospholipid content. Free fatty acids (A4) are determined on a phospholipid-free extract by a procedure based on partitioning the fatty acids as copper soaps into chloroform, and subsequent photometric determination of the copper with diethyldithiocarbamate. Phospholipids, as well as the free fatty acids present in the total lipid-extract, are measured by the same method, since they also form a complex with copper that is soluble in chloroform. A criticism of this technique is that equal response is not given by dipalmitoyl lecithin, dipalmitoyl cephalin, or beef brain sphingomyelin. 

Results. Similar absorbances are found for triolein, cholesterol oleate, dipalmitoyl lecithin, and dipalmitoyl cephalin. Sphingomyelin, which has an amide fatty acid linkage, does not undergo hydroxylaminolysis. The standard error of the method is 0.36 mEq for an acyl ester concentration of 7-20 mEq/liter serum. 

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... 

Baer (1953) has recorded the spectra of pure dimyristoyl, dipalmitoyl, and distearoyl L-a-lecithins. Baer et al. (1952) have also recorded spectra of L- -cephalins, namely, the same kinds of fatty acid derivatives. The spectra have differences, although this is not true for the corresponding straight-chain fatty acids. In the region from 870 to 714 cm" several large differences occur. 

The fatty acid portions are usually palmityl, stearyl, or oleyl. The structure shown is a cephalin the three protons on the nitrogen are replaced by methyl groups in the lecithins. Both types of phospholipids are widely distributed in the body, especially in... 

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) ... 

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 cephalins). The phosphoglycerides are particularly important in membrane formation. 

Phospholipids A lipid containing phosphorus which on hydrolysis yields fatty acids, glycerin, and a nitrogenous compound. Lecithin cephalin and sphingomyelin are the best known examples. 

Phospholipase hydrolyzes the ester linkage of the unsaturated fatty acid in an a position on the glycerol moiety of lecithin to yield lysolecithin, a powerful hemolytic agent. The enzyme occurs in snake venom and in tissue extracts including the pancreas. Both lecithins and cephalins are split, but triglycerides and sphingomyelins are not attacked. ... 

Removes remaining fatty acid from lysolecithin or lysocephalin No action on lecithin or cephalin Probably a mixture of Lecithinaae A and Lysolecithinase... 

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