Ethanolamine-cephalin

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 ethanolamine (cephalin) phospholipid commonly C7Hj2NOgP(2R) found in microorganisms, but largely absent in plants. 

Fig. 139. Thin-layer chromatogram of polar lipids [210]. Layer silica gel G solvent chloroform-methanol-water (65-h 25-f 4) time of run 2h spray reagents rhodamine B in ethanol (UV light) and Dragendorff-reagent amounts 50—100 (xg of each. 1 lysolecithin 2 sphingomyelin 3 lecithin 4 ethanolamine-cephalin ...

Phosphatidyl Ethanolamines (Cephalins) These glycerophospholipids have previously been named cephalins. However, it is now known that, in addition to phosphatidyl ethanolamine, phosphatidyl serine and phosphatidyl inositol also... 

The most common phospholipids are phosphatidyl esters in which phosphatidic acid is esterified with another hydroxy compound to form a diester of phosphoric acid. Incorporation of choline and ethanolamine as the hydroxy compound would result in the formation of phosphatidylcholine (lecithin) and phosphatidyl ethanolamine (cephaline), respectively. There are enzymes specifically hydrolyze one or more of the four ester bonds in phospholipids and/or galactolipid. Each of the enzymes, phospholipase Ai (PL-Ai), phospholipase A2 (PL-A2), phospholipase C (PL-C), and phospholipase D (PL-D), cleaves a phosphatidyl ester into two products as shown in Figure 1. 

The Cephalins differ from lecithins in their low solubility in alcohol. They con t of two main fractions, the ethanolamine cephalins and the serine cephalins. As is evident from the partial formulas, the base ethanolamine, HO—CH —CHj— NH2, or the amino acid serine, HO—CH —CH(COOH)—NH2, replaces choline. Serine is the biochemical precursor of ethanolamine and ethanolamine cephalins can be methylated (with active methionine) to form lecithins (cf. Chapt. VIII-12). The three phosphatides are therefore closely related biogenetically. 

Ethanolamine cephalins are formed in the same way, i.e. ethanolamine is activated with CDP and transferred onto a diglyceride. Cephalins may be methylated to produce lecithins with adenosylmethionine as methyl group donor. This methyla-tion apparently is the main biosynthetic pathway of lecithin and is an important source of choline from ethanolamine (Greenberg and Bremer). 

Phosphatidylethanolamine (cephalin) and ph os-phatidylserine (found in most tissues) differ from phosphatidylcholine only in that ethanolamine or serine, respectively, replaces choline (Figure 14-8). 

Phosphatidyl ethanolamines —ch2ch2nh3 Large amounts in animals, plants and microorganisms Old trivial name is cephalin. Methyl and dimethyl ethanolamine derivatives also occur... 

Phosphatidylcholine (lecithin) is the most abundant phospholipid in membranes. Phosphatidylethanolamine (cephalin) has an ethanolamine residue instead of choline, and phosphatidylserine has a serine residue. In phosphatidylinositol, phosphatidate is esterified with the sugarlike cyclic polyalcohol myo-inositol. A doubly phosphorylated derivative of this phospholipid, phosphatidylinositol 4,5-bisphosphate, is a special component of membranes, which, by enzymatic cleavage, can give rise to two second messengers, diacylglycerol (DAG) and inositol l,4,5trisphosphate (InsPsi see p.386). 

Dihexadecanoyl lecithin is used to represent all individual phospholipids except phosphatidyl ethanolamine, which is calibrated by dihexadecanoyl cephalin. 

Serine Phosphatidyl serine Ethanolamine Phosphatidyl ethanolamine (a-cephalins)... 

Cephalins are glycerophospholipids present in foods. They differ from lecithins by having ethanolamine or serine instead of choline in their structure. Could you differentiate between lecithins and cephalins on the basis of the three tests to be performed in this experiment ... 

Folch, J. (1942) Brain cephalin, a mixture of phosphatides. Separation from it of phosphatidyl serine, phosphatidyl ethanolamine and a fraction containing an inositol phosphatide, J. Biol. Chem. 146, 35-44. 

Many phospholipids contain an additional alcohol esterified to the phosphoric acid group. Cephalins are esters of ethanolamine, and lecithins are esters of choline. Both cephalins and lecithins are widely found in plant and animal tissues. 

PE (trivial name cephalin ) also has a net neutral charge (Fig. 1). PE is widespread and usually the second most abundant phospholipid in animal and plant membranes. It is also the main lipid component of microbial membranes. In animal tissues, phosphatidylethanolamine may exist in diacyl, aUcylacyl and alkenylacyl forms. Moreover, animal phosphatidylethanolamine usually contains higher levels of arachidonic and docosahex-aenoic acids in comparison with the other zwitterionic phospholipid, PC. The partly methylated derivatives of PE (phos-phatidyl-A -methyl-ethanolamine, phosphatidyl-Af -dimethyl-... 

Glycerophospholipids which can be analysed in this way [285] include the cephalins (R = ethanolamine), phosphatidylserine [287], phos-phatidylinositol, and phosphatidylcholine. 

The cephalin differs from lecithin only in the nitrogenous group where ethanolamine is present instead of choline. 

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. 

Phosphatidic acids are the simplest phosphoacylglycerols and are present only in small amounts in membranes. The most common phosphoacylglycerols in membranes have a second phosphate ester linkage. The alcohols most commonly used to form this second ester group are ethanolamine, choline, and serine. Phosphatidylethanolamines are also called cephalins, and phosphatidylcholines are called lecithins. Used as emulsifying agents, lecithins are added to foods such as mayonnaise to prevent the aqueous and fat components from separating. 

Phosphoglycerides in which the alcohol is ethanolamine or serine, rather than choline, are called cephalins. They are found in most cell membranes and are particularly abundant... 

LEARNING CHECK 8.5 ] )raw a typical structure for a cephalin containing the cation of ethanolamine ... 

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