Enzymatic synthesis of a 2-O-α-d-glucopyranosyl cyclic tetrasaccharide by kojibiose phosphorylase Original Research Article

The glucosyl transfer reaction of kojibiose phosphorylase (KPase) from Thermoanaerobacter brockii ATCC35047 was examined using cyclo-{→6)-α-d-Glcp-(1→3)-α-d-Glcp-(1→6)-α-d-Glcp-(1→3)-α-d-Glcp-(1→} (CTS) as an acceptor. KPase produced four transfer products, saccharides 1–4. The structure of a major product, saccharide 4, was 2-O-α-d-glucopyranosyl-CTS, cyclo-{→6)-α-d-Glcp-(1→3)-α-d-Glcp-(1→6)-[α-d-Glcp-(1→2)]-α-d-Glcp-(1→3)-α-d-Glcp-(1→}. The other transfer products, saccharides 1–3, were 2-O-α-kojibiosyl-, 2-O-α-kojitriosyl-, and 2-O-α-kojitetraosyl-CTS, respectively. These results showed that KPase transferred a glucose residue to the C-2 position at the ring glucose residue of CTS. This enzyme also catalyzed the chain-extending reaction of the side chain of 2-O-α-d-glycopyranosyl-CTS.