title: Traceless labeling of glycoproteins and its application to the study of glycoprotein-protein interactions.
abstract: A new chemical method for the traceless labeling of glycoproteins with synthetic boronic acid (BA)-tosyl probes was successfully developed. The BA moiety acts as an affinity head to direct the formation of a cyclic boronate diester with the diol groups of glycans. Following this step, the electrophilic tosyl group is displaced by an SN2 reaction with a nucleophilic residue of the boronated glycoprotein, and finally, a reporter group is tagged onto the glycoprotein via an ether linkage. In the presence of polyols, a competition reaction recovers the native glycan of the tagged glycoprotein, conserving its biological significance. The BA-tosyl probes were used successfully for the specific labeling of glycosylated fetuins in a mixed protein pool and from crude Escherichia coli (E. coli) lysate. Further, a BA-tosyl-functionalized glass slide was used to fabricate glycoprotein microarrays with highly conserved glycans. By interacting with various lectins (carbohydrate-binding proteins), such as Concanavalin A (Con A) and wheat germ agglutinin (WGA), the types of carbohydrates and specific linkages of glycoproteins (α or β) could be systematically monitored. It is believed that the newly developed method will greatly accelerate the understanding of glycoproteins.
authors.affiliation: Department of Chemistry, National Sun Yat-sen University , Kaohsiung 804, Taiwan.
authors.forename: Yung-Lin
authors.initials: YL
authors.lastname: Yang
authors.forename: Yen-Pin
authors.initials: YP
authors.lastname: Lee
authors.forename: Yen-Ling
authors.initials: YL
authors.lastname: Yang
authors.forename: Po-Chiao
authors.initials: PC
authors.lastname: Lin
mesh_terms: D000818:Animals; D001897:Boronic Acids / Q000737:chemistry; D002417:Cattle; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000032:analysis / Q000378:metabolism; D060748:Fetuins / Q000032:analysis / Q000378:metabolism; D006023:Glycoproteins / Q000032:analysis / Q000378:metabolism*; D006031:Glycosylation; D037102:Lectins / Q000378:metabolism; D015335:Molecular Probes / Q000737:chemistry; D040081:Protein Array Analysis / Q000379:methods*; D025941:Protein Interaction Mapping / Q000379:methods*; D014105:Tosyl Compounds / Q000737:chemistry
chemical_list: D001897:Boronic Acids; D029968:Escherichia coli Proteins; D060748:Fetuins; D006023:Glycoproteins; D037102:Lectins; D015335:Molecular Probes; D014105:Tosyl Compounds