Partial synthesis and properties of a series of N-acyl sphingomyelins.
A series of sphingomyelins (SM) with different chain length fatty acids (C14:0, C16:0, C18:0, C20:0, C22:0, and C24:0) N-linked to the primary amino group of sphingosine have been synthesized starting with bovine brain SM. Two different acid hydrolysis procedures, butanolic HCl (H. Kaller, 1961. Biochem. Z. 334: 451-456) and methanolic HCl (R.C. Gaver and C.C. Sweeley. 1965. J. Am. Oil Chem. Soc. 42: 294-298), were used and the resultant sphingosylphosphocholine (SPC) was converted to SM using two acylation methods: using fatty acid imidazolide to yield the O-acyl, N-acyl SPC, followed by mild alkaline hydrolysis for selective deacylation at the O-acyl linkage, and selective acylation at the amino group of SPC using the free fatty acid in the presence of dicyclohexylcarbodimide. Following chromatographic purification, N-acyl SM were obtained in high yield (80-90%), and were characterized by a combination of thin-layer chromatography, high performance liquid chromatography, chemical analysis, optical rotation, circular dichroism, infrared spectroscopy, 13C NMR, and sphingosine base analysis. The N-acyl SM were chemically homogeneous with respect to fatty acid composition and the sphingosine base composition resembled that of the starting bovine brain SM. However, as a consequence of the epimerization at C-3 of SPC in both acid hydrolysis procedures, the resulting N-acyl SM consisted of mixtures of D-erythro and L-threo sphingomyelins. By differential scanning calorimetry hydrated C14:0 to C24:0 SM exhibited gel-liquid crystal transitions in the range 30-50 degrees C but the chain length dependence was complex.(ABSTRACT TRUNCATED AT 250 WORDS)
D000215:Acylation; D000818:Animals; D001923:Brain Chemistry; D002152:Calorimetry, Differential Scanning; D002417:Cattle; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D010767:Phosphorylcholine / Q000031:analogs & derivatives / Q000302:isolation & purification; D013109:Sphingomyelins / Q000138:chemical synthesis*; D013110:Sphingosine / Q000031:analogs & derivatives / Q000302:isolation & purification; D013237:Stereoisomerism; D014961:X-Ray Diffraction
D013109:Sphingomyelins; C005356:sphingosine phosphorylcholine; D010767:Phosphorylcholine; D013110:Sphingosine