Isolation and characterization of a novel α-glucosidase with transglycosylation activity from Arthrobacter sp. DL001

A strain of Arthrobacter sp. DL001 with high transglycosylation activity was successfully isolated from the Yellow Sea of China. To purify the extracellular enzyme responsible for transglycosylation, a four-step protocol was adopted and the enzyme with electrophoretical purity was obtained. The purified enzyme has a molecular mass of 210 kDa and displays a narrow hydrolysis specificity towards α-1,4-glucosidic bond. Its hydrolytic activity was identified as decreasing in the order of maltotriose > panose > maltose. Only 3.61% maltose activity occurs when p-nitrophenyl α-d-glycopyranoside serves as a substrate, suggesting that this enzyme belongs to the type II α-glucosidase. In addition, the enzyme was able to transfer glucosyl groups from the donors containing α-1,4-glucosidic bond specific to glucosides, xylosides and alkyl alcohols in α-1,4- or α-1,6-manners. A decreased order of activity was observed when maltose, maltotriose, panose, β-cyclodextrin and soluble starch served as glycosyl donors, respectively. When maltose was utilized as a donor and a series of p-nitrophenyl-glycosides as acceptors, the glucosidase was capable of transferring glucosyl groups to p-nitrophenyl-glucosides and p-nitrophenyl-xylosides in α-1,4- or α-1,6-manners. The yields of p-nitrophenyl-oligosaccharides could reach 42–60% in 2 h. When a series of alkyl alcohols were utilized as acceptors, the enzyme exhibited its transglycosylation activities not only to the primary alcohols but also to the secondary alcohols with carbon chain length 1–4. Therefore, all the results indicated that the purified α-glucosidase present a useful tool for the biosynthesis of oligosaccharides and alkyl glucosides.