18:sphingosine acylation

The high water solubility of these adamantyl GSL derivatives was surprising considering that the adamantane frame is at least as hydrophobic as the fatty acid it replaced. It is possible, however, that the adamantane frame together with the sphingosine acyl chain may pack sufficiently to be below the hydrophobic size that is necessary to disturb the molecular organization of water (211). This situation may provide the basis of their aqueous solubility characteristics. 

Farber s disease Ceramidase Acyl-i-Sphingosine Ceramide Hoarseness, dermatitis, skeletal deformation, mental retardation fatal in early life. 

Figure 22.6 Sphingolipids are constructed of sphingosine derivatives containing an acylated fatty acid and a head group attached to the hydroxyl.

The amino group of sphingosine is acylated with long-chain fatty acids and the N-acylated product is termed a ceramide (Fig. 3-3). C-l of ceramide is linked to different... 

Sphinganine is acylated, then dehydrogenated to form ceramide. Free sphingosine, also termed sphingenine, salvaged from sphingolipid breakdown can be enzymatically acylated with acyl-CoA to form ceramide. 

Figure 12.12 Sphingomyelins. Sphingomyelins are esters of a ceramide and phospho-ryl choline. However, similar compounds are ceramide-1-phosphoryl ethanolamines and phosphono forms of sphingolipids. Ceramides W-acyl-sphingosines) are amides of a long chain di- or trihydroxy base containing 12 to 22 carbon atoms, of which sphingosine (4-sphingenine) is the commonest, and a long chain fatty acid whose acyl chain is shown by R1. This may contain up to 26 carbon atoms.

This enzyme [EC 3.5.1.23], also known as acylsphingo-sine deacylase, catalyzes the hydrolysis of an A-acyl-sphingosine to produce a fatty acid anion and sphin-gosine. 

More complex structures, often related to natural products are prepared by organic synthesis. Among them can be mentioned (f )-3-hydroxytetradecanoic acid (the double-tail hydrophobic moiety of lipid A), sphingosine derivatives related to the ceramides or 1,2- and l,3-dialkyl(acyl)glycerols related to glyco-glycerolipids, glycerophospholipids, and GPI anchors of membrane proteins. The preparations of the above derivatives were reported several years ago but some improvements have been published more recently. 

S ATP -I- ceramide <1, 2, 3, 4> (<1> other name n-acyl-sphingosine, no activity with CTP, CDPcholine and UDPglucose [1] <2> no activity with... 

The glycosphingolipids of mammals are known to be cellular-membrane components,1"5 organized in such a way that their lipid moiety, namely, acylated sphingosine (usually called ceramide), is submerged into the outer leaflet of the plasma-membrane bilayer, and contributes to its structural... 

A partial synthesis of cerebroside sulfate [ sulfatide, the glycoside of ceramide with galactose 3-sulfate, (90)] was achieved [90] by acylating the sphingosine galactosyl 3-sulfate (89) (obtained by basic hydrolysis of natural sulfatide) with palmitoyl chloride or D-2-acetoxypalmitoyl chloride (and subsequent basic hydrolysis of the... 

Other compound classes in the synthesis of which chiral 3-carbon synthons were used include sphingosine chains (32), 3-amino-2-azetidinones (33), (3,y-unsaturated-a-amino acids 34), fluorinated macrocyclic bis(indolyl) maleimides35, fluorocyclopropyl alcohols (36), l-O-phosphocholine-2-O-acyl-octadecanes and l-Ophosphocholine-2-N-acyl-octadecane (37) diacyl glycerols 38-42) and analogs of fragments of leukotriene-B4 43). 

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