Novel modification of glycosphingolipids by long-chain cyclic acetals: isolation and characterization of plasmalocerebroside from human brain.
A glycosphingolipid component of human brain, having long-chain cyclic acetals, has been isolated and characterized. This compound incorporates a novel type of natural glycan modification, in which a long-chain aliphatic aldehyde is conjugated through a cyclic acetal (plasmal) linkage to the galactosyl moiety of cerebroside. In addition to components normally observed by gas chromatography-mass spectrometry (GC-MS) following methanolysis of cerebroside (fatty acid methyl esters, methyl alpha- and beta-galactosides, sphingosine), this compound produced 16:0, 18:0, and 18:1 fatty aldehydes, unequivocally identified as their enol methyl ether derivatives. Results of positive ion fast atom bombardment mass spectrometry (FAB-MS) of the native compound, and GC-MS of partially methylated hexitol acetates derived from the permethylated derivative, were consistent with structures of galactocerebroside having 3,4- and 4,6-linked cyclic plasmal substituents, as shown. [formula: see text]
Levery
S B
SB
Biomembrane Institute, Seattle, Washington 98119.
Nudelman
E D
ED
Hakomori
S
S
D000080:Acetals / Q000737:chemistry*; D000447:Aldehydes / Q000032:analysis; D001923:Brain Chemistry; D002554:Cerebrosides / Q000737:chemistry / Q000302:isolation & purification*; D005227:Fatty Acids / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry; D006028:Glycosphingolipids / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D013058:Mass Spectrometry; D008745:Methylation; D015394:Molecular Structure; D009005:Monosaccharides / Q000032:analysis
D000080:Acetals; D000447:Aldehydes; D002554:Cerebrosides; D005227:Fatty Acids; D006028:Glycosphingolipids; D009005:Monosaccharides