Chemoenzymatic synthesis and lectin array characterization of a class of N-glycan clusters.
N-Glycans are major components of many glycoproteins. These sugar moieties are frequently involved in important physiological and disease processes via their interactions with a variety of glycan-binding proteins (GBP). Clustering effect is an important feature in many glycan-lectin interactions. We describe in this paper a chemoenzymatic synthesis of novel N-glycan clusters using a tandem endoglycosidase-catalyzed transglycosylation. It was found that the internal beta-1,2-linked GlcNAc moieties in the N-glycan core, once exposed in the nonreducing terminus, was able to serve as acceptors for transglycosylation catalyzed by Endo-A and EndoM-N175A. This efficient chemoenzymatic method allows a quick extension of the sugar chains to form a class of glycan clusters in which sugar residues are all connected by native glycosidic linkages found in natural N-glycans. In addition, a discriminative enzymatic reaction at the two GlcNAc residues could be fulfilled to afford novel hybrid clusters. Lectin microarray studies revealed unusual properties in glyco-epitope expression by this panel of structurally well-defined synthetic N-glycans. These new compounds are likely valuable for functional glycomics studies to unveil new functions of both glycans and carbohydrate-binding proteins.
Huang
Wei
W
Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
Wang
Denong
D
Yamada
Masao
M
Wang
Lai-Xi
LX
D002384:Catalysis; D037102:Lectins / Q000737:chemistry*; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase / Q000737:chemistry* / Q000378:metabolism; D011134:Polysaccharides / Q000138:chemical synthesis* / Q000737:chemistry / Q000145:classification*; D040081:Protein Array Analysis
D037102:Lectins; D011134:Polysaccharides; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase