Synthesis of fluorescent and radioactive analogues of two lactosylceramides and glucosylceramide containing beta-thioglycosidic bonds that are resistant to enzymatic degradation.
Condensation of 2-S-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)-2- thiopseudourea hydrobromide with 2,3,6-tri-O-benzoyl-4-O-trifluoromethylsulfonyl-beta-D-galactopyra nosyl- (1-->1)-(2S,3R,4E)-3-O-benzoyl-2-dichloroacetamido-4-octa decen-1,3-diol afforded S-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)-(1-->4)-2,3,6-tri-O- benzoyl-4-thio-beta-D-glucopyranosyl-(1-->1)-(2S,3R,4E)-3-O-benzoy l-2- dichloroacetamido-4-octadecen-1,3-diol in good yield. Removal of the protecting groups, followed by selective N-acylation of the sphingosine amino group with either a fluorescent or a radioactive fatty acid, gave labeled lactosylceramide analogues in good yield. Since these products contained a beta-thioglycosidic bond between the two sugar moieties, they were totally resistant to the action of acid lysosomal glycosidases. Likewise, condensation of 2-S-(2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl)-2- thiopseudourea hydrobromide and 2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl-(1-->4)-2,3,6- tri-O-acetyl-1-S-acetyl-1-thio-beta-D-glucopyranose with (2R,3R,4E)-3-O-benzoyl-2-dichloroacetamido-1-iodo-4-octad ecen-3-ol in methanolic sodium acetate afforded the corresponding beta-thioglycosides 14 and 16, respectively, in good yield. These beta-thioglycosides were converted into glucosylceramide and lactosylceramide analogues following removal of the protecting groups and by subsequent selective N-acylation using either a fluorescent or adioactive fatty acid N-succinimidyl ester. Whereas the glucosylthioceramides thus obtained proved to be completely undegradable by lysosomal glucocerebrosidase, the lactosylceramides containing the beta-thioglycosidic bond between the lactose and the ceramide residues could be degraded by lysosomal GM1-beta-galactosidase to give the corresponding glucosylthioceramides. These compound did not yield to any further enzymatic degradation.
Institut für Organische Chemie und Biochemie, Universität Bonn, Germany.
B
B
Albrecht
U
U
Pütz
G
G
Schwarzmann
D002240:Carbohydrate Sequence; D002855:Chromatography, Thin Layer; D005453:Fluorescence; D005962:Glucosylceramidase / Q000378:metabolism; D005963:Glucosylceramides / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D006028:Glycosphingolipids / Q000378:metabolism; D007790:Lactosylceramides / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D015394:Molecular Structure; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013865:Thioglycosides / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
D005963:Glucosylceramides; D006028:Glycosphingolipids; D007790:Lactosylceramides; D013865:Thioglycosides; D001616:beta-Galactosidase; D005962:Glucosylceramidase