SPACER-MODIFIED TRISACCHARIDE GLYCOSIDES THAT MIMIC THE BIANTENNARY ASN-LINKED OLIGOSACCHARIDE ACCEPTOR OF (1-]4)-BETA-D-GALACTOSYLTRANSFERASE AND CAN BE USED AS COMPETITIVE INHIBITORS AND FOR IRREVERSIBLE DEACTIVATION

The biantennary spacer-modified trisaccharide glycoside methyl 3,6-di-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyloxyethyl)-alpha-D-mannopyranoside (5) was synthesised and used together with several 2-acylamino-2-deoxy-D-glucose derivatives in competition experiments with beta-D-galactosyltransferase. CoMpound 5 was an acceptor substrate (K(M) 0.18 mM) comparable to the biantennary core heptasaccharide of glycoproteins (K(M) 0.13 mM). Replacing the N-acetyl group by other N-acyl groups did not alter the kinetic parameters significantly. When the N-acyl group was iodoacetyl, the compound was an irreversible inhibitor,