Influence of L-fucose attached α1→6 to the asparagine-linked N-acetylglucosamine on the hydrolysis of the N-glycosidic linkage by human glycosylasparaginase

Open Access
Publisher Website
Google Scholar
Abstract
The sequence of hydrolytic reactions in the catabolism of the N-glycosidic oligosaccharide-to-protein region containing 6-linked fucose on the asparagine-linked N-acetylglu-cosamine may vary from species to species. When α-L-fucopyranosyl-(1→6)-2-acetamido-1-N-(β-L-aspartyl)-2-deoxy-β-D-glucopyranosylamine (Fuc-GlcNAc-Asn) was incubated with recombinant human glycosylasparaginase, no hydrolysis of the N-glycosidic bond was detected. After removal of the α1→6-linked fucose from the compound by α-fucosidase, the residual GlcNAc-Asn was rapidly hydrolyzed by glycosylasparaginase. Enzymologically this demonstrates for the first time that the catabolism of Fuc-GlcNAc-Asn in humans occurs via consecutive action of α-fucosidase and glycosylasparaginase. The hydrolysis rate of GlcNAc-Asn by glycosylasparaginase remained unaffected in the presence of Fuc-GlcNAc-Asn or several different monosaccharides including fucose. This indicates that any fucose attached a 1→6 to the asparagine-linked N-acetylglucosamine residue prevents the access of the L-asparagine residue of Fuc-GlcNAc-Asn into the deep, funnel-shaped active site of human glycosylasparaginase. These findings explain the accumulation of fucosylated and normal catabolism of nonfucosylated glycoasparagines in fucosidosis.

This publication has 0 references indexed in Scilit: