Environmentally benign glycosylation of aryl pyranosides and aryl/alkyl furanosides demonstrating the versatility of thermostable CGTase from Thermoanaerobacterium sp.

Abstract : An extensive study on the specificity of transglycosylation and disproportionation of Thermoanaerobacterium sp. cyclodextrin glucosyltranferases against aryl glucopyranosides or furanosides was achieved. While a mixture of maltoside and isomaltoside was obtained respectively using p-nitrophenyl glucopyranoside as acceptor, only one regioisomer, namely the p-nitrophenyl α-D-Glcp-(1,3)-α-L-Araf was isolated using p-nitrophenyl arabinofuranoside as acceptor. Interestingly, similar outcomes were found when using p-nitrophenyl galactofuranoside. Furthermore, activation by microwave irradiation resulted in faster reaction times and higher yields and led to glucosidic oligosaccharides with up to 70% conversion. The influence of the anomeric and C-4 configurations of the glycosidic acceptors on the transglycosylation, previously stated for the CGTase family, was not observed and unconventional substrate specificity towards alkyl furanosides was highlighted.