Glycopeptide synthesis through endo-glycosidase-catalyzed oligosaccharide transfer of sugar oxazolines: Probing substrate structural requirement

Article abstract of DOI:10.1002/chem.200501196

An array of sugar oxazolines was synthesized and tested as donor substrates for the Arthrobacter endo-ssN-acetylglucosaminidase (Endo-A)-catalyzed glycopeptide synthesis. The experiments revealed that the minimum structure of the donor substrate required for Endo-A catalyzed transglycosylation is a Manss1→4-GlcNAc oxazoline moiety. Replacement of the ss-D-Man moiety with ss-D-Glc, ss-D-Gal, and ss-D-GlcNAc monosaccharides resulted in the loss of substrate activity for the disaccharide oxazoline. Despite this, the enzyme could tolerate modifications such as attachment of additional sugar residues or a functional group at the 3- and/or 6-positions of the ss-D-Man moiety, thus allowing a successful transfer of selectively modified oligosaccharides to the peptide acceptor. On the other hand, the enzyme has a great flexibility for the acceptor portion and could take both small and large GlcNAc-peptides as the acceptor. The studies implicate a great potential of the endoglycosidase-catalyzed transglycosylation for constructing both natural and selectively modified glycopeptides.