Specificity of β1,4-galactosyltransferase inhibition by 2-naphthyl 2-butanamido-2-deoxy-1-thio-β-D-glucopyranoside.
Inhibitors of Galactosyltransferase (GalT) have the potential of reducing the amounts of adhesive carbohydrates on secreted and cell surface-bound glycoproteins. We recently found a potent inhibitor of β4GalT, 2-naphthyl 2-butanamido-2-deoxy-1-thio-β-D-glucopyranoside (compound 612). In this work, we have tested compound 612 for the specificity of its inhibition and examined its effect on GalT, and on GlcNAc- and GalNAc-transferases in homogenates of different cell lines, as well as on recombinant glycosyltransferases. Compound 612 was found to be a specific inhibitor of β4GalT. The specificity of recombinant human β3GalT5 that also acts on GlcNAc-R substrates, revealed similarities to bovine milk β4GalT. However, 612 was a poor substrate and not an inhibitor for β3GalT5. To further determine the specific structures responsible for the inhibitory property of 612, we synthesized (2-naphthyl)-2-butanamido-2-deoxy-β-D-glucopyranosylamine (compound 629) containing nitrogen in the glycosidic linkage, and compared it to other naphthyl and quinolinyl derivatives of GlcNAc as substrates and inhibitors. Compound 629 was a substrate for both β4GalT and β3GalT5. This suggests that properties of 612 other than the presence of the naphthyl ring alone were responsible for its inhibitory action. The results suggest a usefulness of 612 in specifically blocking the synthesis of type 2 chains and thus epitopes attached to type 2 chains. In addition, 612 potently inhibits β4GalT in cell homogenates and thus allows assaying β3GalT activity in the presence of β4GalT.
Department of Medicine, Division of Rheumatology, Queen's University, Kingston, ON, K7L 3N6, Canada.
Yin
Y
Gao
Carmen
C
Lazar
Walter A
WA
Szarek
Inka
I
Brockhausen
D000818:Animals; D002417:Cattle; D002460:Cell Line; D057075:Enzyme Assays; D005700:Galactosyltransferases / Q000037:antagonists & inhibitors*; D006801:Humans; D051379:Mice; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry; D013329:Structure-Activity Relationship; D013863:Thioglucosides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
C557507:2-naphthyl 2-butanamido-2-deoxy-1-thioglucopyranoside; D011994:Recombinant Proteins; D013863:Thioglucosides; D005700:Galactosyltransferases; C493310:beta1,4-galactosyltransferase, human