A-Cephalins

Amphiphilic Molecules. In just about all cases of lyotropic Hquid crystals, the important component of the system is a molecule with two very different parts, one that is hydrophobic and one that is hydrophilic. These molecules are called amphiphilic because when possible they migrate to the iaterface between a polar and nonpolar Hquid. Soaps such as sodium laurate and phosphoHpids such as a-cephalin [5681-36-7] (phosphatidylethanolamine) (2) are important examples of amphiphilic molecules which form Hquid crystal phases (see Lecithin Soap). 

Dilauroyl-sn-glycero-3-phosphoethanolamine ( -dilauroyl-a-cephalin, 3-sn-phosphat-idylethanolamine 1,2-didodecanoyl) [59752-57-7] M 579.8, m 210 , pKes,(d (PO4H), PKes,(2) 10.5 (NH2). Recrystd from EtOH or tetrahydrofuran. [Bevan and Malkin J Chem Soc 2667 /95/ IR Bellamy and Beecher7 Chem Soc 728 1953.]... 

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

Both of these groups and another from Manitoba have offered criticism of certain of the data and conclusions from an earlier study by Dikstetn and Sulman, especially the suggestion that alkylation by Dibenamine involves a cephalin-like fraction of the a-adrenerglc receptor system. 

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

What is the stmctural difference between a lecithin and a cephalin ... 

Under suitable conditions all of the ester (and ether) linkages of a phosphatide can be hydrolyzed. What organic compounds would you expect to obtain from the complete hydrolysis of (see Table 23.5) (a) a lecithin, (b) a cephalin, and (c) a choline-based plasmalogen [Note Pay particular attention to the fate of the o ,/3-unsaturated ether in part (c).]... 

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... 

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