What Are Plasmalogens And Explain The Role Of An Important Plasmalogen?

This is another one of those biochemistry questions which I am sure many of you would have problem answering. There are three major classes of plasmalogens as mentioned as following: Phosphatidalcholines, Phosphatidalethanolamines, and Phosphatidalserines. These phospholipids have a fatty acid attached to carbon 1 in an ether linkage rather than an ester linkage [NOTE: within each class the molecules vary based on the type of moiety attached at carbon 1 and 2]. Myelin contains large amounts of ethanolamine plasmalogen, and heart muscle contains large amounts of ethanolamine plasmalogen. One plasmalogen—1-alkenyl-2-acetyl-phosphatidalcholine is a very powerful chemical mediator. It has potent physiologic actions on a variety of cell types. For example, it causes blood platelet aggregation and degranulation, and was therefore originally called platelet-activating factor (PAF). Other effects of PAF include increasing airway and pulmonary edema in the lungs, serving as a major mediator of hypersensitivity, acute inflammatory reactions, and anaphylactic shock, and causing neutrophilis and alveolar macrophages to generate super oxide radicals. PAF causes these responses by binding to a receptor on cell membranes and activating transmembrane signaling mechanisms including the activation of phospholipids, thus stimulating phospholipids degradation [NOTE: PAF has biologic effects at concentrations as low as 10-12 mol/L in some systems].

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