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.
Gao
Yin
Y
Department of Medicine, Division of Rheumatology, Queen's University, Kingston, ON, K7L 3N6, Canada.
Lazar
Carmen
C
Szarek
Walter A
WA
Brockhausen
Inka
I
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