title: Synthesis of maleimide-activated carbohydrates as chemoselective tags for site-specific glycosylation of peptides and proteins.
abstract: An array of maleimide-activated mono- and oligosaccharides were synthesized to permit site-specific glycosylation of cysteine-containing peptides and proteins. Maleimide-activated monosaccharides, in which the native alpha- or beta-O-glycosidic linkages found for nonreducing terminal sugars of native glycoproteins are preserved, were prepared using 2'-aminoethyl glycosides as the key intermediates. In addition, a native high-mannose type oligosaccharide, Man(9)GlcNAc(2)Asn, was converted into its maleimide-activated form by taking advantage of the existing amino group in the Asn portion. The application of these maleimide-activated carbohydrates was exemplified by the site-specific glycosylation of a 36-mer HIV-1 gp41 peptide, T20, which is a potent inhibitor against HIV infection. The chemoselective ligation was found to be rapid, highly efficient, and essentially quantitative. Tagging the biologically active peptide with a mannose and/or oligomannose moiety will be useful for targeting the drug to macrophage and dendritic cells, which are primary targets for HIV-1 infection and are expressing mannose- and oligomanose-specific receptors on their surface. In combination with site-specific mutagenesis, the maleimide-activated carbohydrates can serve as generally applicable tags for site-specific glycosylation of proteins via the highly efficient maleimide-thiol ligation reaction.
authors.affiliation: Institute of Human Virology, University of Maryland Biotechnology Institute, University of Maryland, 725 W. Lombard Street, Baltimore, Maryland 21201, USA.
authors.forename: Jiahong
authors.initials: J
authors.lastname: Ni
authors.forename: Suddham
authors.initials: S
authors.lastname: Singh
authors.forename: Lai-Xi
authors.initials: LX
authors.lastname: Wang
mesh_terms: D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000737:chemistry*; D016503:Drug Delivery Systems; D000077560:Enfuvirtide; D006001:Glycoconjugates / Q000138:chemical synthesis*; D006031:Glycosylation; D015700:HIV Envelope Protein gp41 / Q000737:chemistry; D008301:Maleimides / Q000737:chemistry*; D008358:Mannose; D009005:Monosaccharides / Q000737:chemistry; D009844:Oligosaccharides / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry*
chemical_list: D002241:Carbohydrates; D006001:Glycoconjugates; D015700:HIV Envelope Protein gp41; D008301:Maleimides; D009005:Monosaccharides; D009844:Oligosaccharides; D010446:Peptide Fragments; D010455:Peptides; D011506:Proteins; D000077560:Enfuvirtide; C043592:maleimide; D008358:Mannose