Ceramide phosphorylcholine

The addition of phosphorylcholine to ceramide produces sphingomyelin (Fig. 36.2). Sphingomyehn (also known as ceramide phosphorylcholine) is analogous to phosphatidylcholine. 

Structural components and function of sphingomyelin The alcohol sphingosine attached to a long-chain fatty acid produces a ceramide. Addition of a phosphorylcholine produces the phospholipid sphingomyelin, which is the only significant sphingophospholipid in humans. It is an important constituent of myelin. 

Sphingomyelin (SPH) is the major representative of the sphingophospholipids. This phospholipid consists of a ceramide unit, containing a fatty acid linked by an amide bond to the amine group of a long-chain base called sphingosine, linked at position 1 to phosphorylcholine (Fig. 1). It is a major component of animal complex lipids, but is not present in plants or microorganisms. 

Sphingomyelin (ceramide 1-phosphorylcholine, compound 1, Fig. 3) is a phospholipid in which the terminal hydroxy group... 

Sphingomyelin is probably synthesized by an exchange reaction in which the phosphorylcholine moiety of phosphatidylcholine is transferred to ceramide ... 

Partial answers to the pathogenesis of Niemann-Pick disease have been obtained recently. An enzyme, sphingomyelinase, which hydrolyzes sphingomyelin to yield phosphorylcholine and ceramide has been found and partially purified from liver. Drastic reduction in the activity of this enzyme has been found in at least some patients with Niemann-Pick disease (see Fig. 3-40). In other cases the biochemical defect remains unknown [125], especially in those forms of the disease in which cholesterol accumulates (Nova Scotia variant). 

It is also known from the work of Sribney and Kennedy (1958) that many tissues contain an enzyme (CDP-choline ceramide cholinephosphotransferase EC 2.7.8.a) capable of transfering phosphorylcholine from CDP-choline to ceramide with the formation of sphingomyelin ... 

Sphingomyelin, the diester of phosphoric acid with choline and ceramide 0 -phosphorylcholine ceramide. 

Sribney and Kennedy (1958) observed that for the phosphorylcholine-ceramide transferase reaction only threosphingosine could serve as substrate. They... 

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