Stearoyl sphingosine

The electron-impact mass spectrum of the 1,3-di-O-TMS ether derivative of A/-stearoyl-sphingosine is illustrated in Figure 8.14 [786,789]. A molecular ion... 

Figure 8.14. The mass spectrum of 1,3-di-0-trimethylsilyl-A/-stearoyl sphingosine [789], (Reproduced by kind permission of the authors and of Chemistry and Physics of Lipids, and redrawn from the original paper).

This enzyme, which has been purified some 200-fold, also catalyzes the synthesis of ceramide from sphingosine and free fatty acid. Acyl CoA derivatives are active only after hydrolysis by thiolase to release free fatty acid which is then available to condense with sphingosine. Attempts to dissociate these enzymic processes from one another have been unsuccessful. The preparation showed hydrolytic activity (ceramidase) toward A-palmitoyl, oleoyl, and stearoyl sphingosine, as well as with. V-palmitoyl dihydrosphingosine. Cerefarosides, sphingomyelin, and iV-acetyl sphingosine were not cleaved. 

Reaction 18 was shown to occur in the presence of guinea-pig or rat-brain microsomes. Ceramides were stated to be inactive as the acceptor of D-galactose residues, but it appears that only N-acetyl-sphingosine was used. Also, inactivity of any of the substrates in these reactions could be due to the lack of proper emulsification. Reaction 19 was postulated by R. O. Brady, when he reported on the first enzymic synthesis of cerehrosides with rat-hrain microsomes and stearoyl- C-CoA. In a reaction mixture containing psychosine as an acceptor, twice as much stearic acid- C was incorporated as in the mixture containing a combination of sphingosine and UDP-D-glucose instead of psychosine. ... 

NMR technique, especially solid state NMR spectrometry, has been frequently used in investigations of the order and mobility of acyl chains within the lipid bilayers. The NMR study of the quadrupole sphtting of deuterons located along the lipid chain permitted to gain information on molecular motions of lipids. For this aim, selectively deuterated lipids have been prepared. 7V-stearoyl sphingomyelin (Figure 7) was deuterium-labelled on different positions of both the sphingosine and the stearoyl chains to capture its motion in membranes. 

Kwon et al. (1996) used ES/MS to characterize the content and composition of SPH isolated from pancreatic islets. More than four molecular species were identified with the most abundant of which containing sphingosine as the long-chain base and palmitic acid as the acyl chain, but stearoyl and arachidoyl species were also found. 

Nine different commercially available ceramides (Ceramide III, IIIB, and VI N-palmitoyl-, V-stearoyl-, V-oleoyl- and V-nervonoyl-D-sphingosine, and V-palmi-toyl- and V-lignoceroyl-DL-dihydrosphingosine) were analyzed on a 30°C Cj colunm (ELSD), drift tube 35 C, N2 at 1 bar) using a 15-tnin 95/5/0 — 35/5/60 acetonitrile/THF/n-propyl alcohol (all phases made lOmM in both triethylamine and formic acid) gradient. The authors studied the effects of mobile phase components (methanol and dichloromethane offered no advantages). Peak area was shown to be a strong positive function of mobile phase modifier concentration from 1 to 10 mM, whereas the overall retention was unaffected [1037]. 

The N-acylation of galactosyl sphingosine in an incubation system was reported by Brady (1962) and Hammarstrom (1971). Curtino Caputto (1974) have demonstrated the enzymatic acylation of glycosyl sphingosine and galactosyl sphingosine by stearoyl CoA using a chicken embryo brain microsomal fraction. 

Alternatively the polymer 51 carrying 0.24 meq lactosyl) (l-l)sphingosine g, chemically prepared from PAN, was sialylated in 55% yield by use of recombinant rat liver a(2-3)sialyltransferase, labeled CMP-NeuAc, and calf intestinal alkaline phosphatase [37]. Again photolysis of the 2-nitrobenzylurethane group in the sialylated polymer 52 followed by acylation with stearoyl chloride afforded the GM3 ganglioside, NeuAca(2-3)Gal)ff(l-4)Glc (l-l)Cer 53. 

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