: The rice BGlu0 beta-D-glucosidase nucleophile mutant E000G is a glycosynthase that catalyzes the synthesis of cellooligosaccharides from alpha-d-glucopyranosyl fluoride ( GlcF ) donor and p-nitrophenyl ( pNP ) cellobioside ( Glc0-pNP ) or cello-oligosaccharide acceptors . 