Enzymatic α-glucosaminylation of maltooligosaccharides catalyzed by phosphorylase

This paper describes phosphorylase-catalyzed enzymatic α-glucosaminylation for the direct incorporation of a 2-amino-2-deoxy-α-d-glucopyranose unit into maltooligosaccharides. When the reaction of 2-amino-2-deoxy-α-d-glucopyranosyl 1-phosphate as the glycosyl donor with maltotetraose as a glycosyl acceptor was performed in the presence of phosphorylase, glucosaminylated oligosaccharides were produced, which were characterized by MALDI-TOF MS measurement after N-acetylation of the crude products. The N-acetylated derivative of the main product in this system was isolated by using HPLC, and its structure was confirmed by MS and 1H NMR spectra. Furthermore, glucoamylase-catalyzed reaction of the isolated compound provided support that the α-glucosamine unit is positioned at the non-reducing end of the oligosaccharide.