Enzymatic α-glucuronylation of maltooligosaccharides using α-glucuronic acid 1-phosphate as glycosyl donor catalyzed by a thermostable phosphorylase from Aquifex aeolicus VF5

This paper describes thermostable phosphorylase-catalyzed alpha-glucuronylation of maltooligosaccharides for the direct synthesis of anionic oligosaccharides having a glucuronic acid residue at the non-reducing end. When the reaction of a-glucuronic acid 1-phosphate (GlcA-1-P) as a glycosyl donor and maltotriose as a glycosyl acceptor was performed in the presence of thermostable phosphorylase from Aquifex aeolicus VF5, high performance anion exchange chromatography analysis of the reaction mixture suggested the production of a glucuronylated tetrasaccharide, whose structure was also confirmed by the MALDI-TOF MS measurement of the crude products. Furthermore, treatment of the crude products with glucoamylase supported that the alpha-glucuronic acid unit was positioned at the non-reducing end of the tetrasaccharide and H-1 NMR analysis suggested that it was bound in an alpha-(1 -> 4)-linkage. When the alpha-glucuronylation of maltotetraose using GlcA-1-P was conducted, alpha-glucuronylated oligosaccharides with various degrees of polymerization were produced. On the other hand, the alpha-glucuronylation of maltotetraose using GlcA-1-P in the presence of potato phosphorylase did not occur at all, indicating no recognition of GlcA-1-P by potato phosphorylase. (C) 2011 Elsevier Ltd. All rights reserved.