Transglycosylation reaction of maltotriose-forming amylase from Streptomyces griseus.

A maltotriose-forming amylase from Streptomyces griseus produced predominantly p-nitrophenyl alpha-maltotetraoside through a transglycosylation reaction from maltotetraose as a donor and p-nitrophenyl alpha-D-glucopyranoside as an acceptor in an organic co-solvent. With p-nitrophenyl beta-D-glucopyranoside acceptor, the enzyme catalyzed the formation of an alpha-(1-->3)-linked tetrasaccharide (p-nitrophenyl 3(1)-O-alpha-maltotriosyl-beta-D-glucopyranoside) in a yield of 16%, based on the acceptor added with its isomer p-nitrophenyl beta-maltotetraoside. This was also the case for the formation of o-chloro-p-nitrophenyl 3(1)-O-alpha-maltotriosyl-beta-D-glucopyranoside with o-chloro-p-nitrophenyl beta-D-glucopyranoside acceptor. The results shows that the anomeric configuration of the aryl group in the glucosyl acceptors had an effect on the position of transglycosylation.