Synthesis of a glioma-related ganglioside, O-Ac GM3 having 3-O-Ac ceramide and its substrate property toward hydrolases.
An O-acetyl group was selectively introduced into the ceramide moiety at the C-3-O on ganglioside GM3 containing N-acetyl neuraminic acid, the product of which has been previously found in rat glioma tissue as a glioma-associated ganglioside. The introduction of the acetyl residue involved a two-step process involving per O-acetylation of GM3 and saponification with a mild alkaline solution in a bilayer system constituted of water and water-immiscible organic solvent. Of the several solvents studied, 2-pentanol and diethyl ether gave the highest yields (68% and 62%, respectively). The chemical structure of the synthesized 3-O-acetyl GM3 was confirmed by proton nuclear magnetic resonance spectroscopy and fast atom bombardment-mass spectrometry, as well as by comparing the mobilities on thin-layer chromatography of its exoglycosidase-digested products with those of the synthesized, authentic 3-O-acetyl-lactosylceramide and ceramide. Furthermore, the substrate specificities of both 3-O-acetyl GM3 and 3-O-acetyl sphingomyelin toward exo- and endo-hydrolases were examined, revealing that they were hardly cleaved by the endoglycoceramidase and sphingolipid N-deacylase for the 3-O-acetyl GM3 and by sphingomyelinase for 3-O-acetyl sphingomyelin. Thus, the enzymes were found to recognize a free C-3 hydroxyl group on ceramide.
Department of Chemistry, School of Medicine, Sapporo Medical University, Japan.
K
K
Tsuchihashi
T
T
Daino
T
T
Akino
S
S
Gasa
D000107:Acetylation; D000818:Animals; D015703:Antigens, CD; D002240:Carbohydrate Sequence; D002518:Ceramides / Q000737:chemistry / Q000378:metabolism*; D004986:Ether; D005679:G(M3) Ganglioside / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D005910:Glioma / Q000737:chemistry*; D006026:Glycoside Hydrolases / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006867:Hydrolases / Q000378:metabolism*; D006868:Hydrolysis; D007790:Lactosylceramides / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D000439:Pentanols; D051381:Rats; D012997:Solvents; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013379:Substrate Specificity
D015703:Antigens, CD; D002518:Ceramides; D005679:G(M3) Ganglioside; D007790:Lactosylceramides; D000439:Pentanols; D012997:Solvents; D004986:Ether; C009744:CDw17 antigen; D006867:Hydrolases; D006026:Glycoside Hydrolases