Synthesis of Azido-Glycans for Chemical Glycomodification of Proteins

Abstract

Chemically produced, accurately linkable oligosaccharides are of importance for the synthesis of neo-glycoproteins. On the route to high-mannose type N-glycans, we present a convenient synthesis of several glycans bearing an azide moiety at the reducing end. An azido-glycan core structure as valuable precursor was modified into the protected N-glycan pentasaccharide core structure and the possibility of modular attachment of different antenna was demonstrated through synthesis of a pentamannose donor and glycosylation with the core structure. The azido function allows for chemical ligation with recombinantly modified proteins featuring noncanonical cyclooctyne amino acids, providing access to customized glycopatterns of glycoproteins, e.g., of antibodies that are of high interest for biopharmaceutical applications.