Characterization of Cellobiose Phosphorylase and Cellodextrin Phosphorylase.

Abstract

Two intracellular enzymes, cellobiose phosphorylase (CBP) and cellodextrin phosphorylase (CDP) are involved in the phosphorolytic pathway in cellulose degradation. Those enzymes are considered to be useful in syntheses of oligosaccharides because the reactions are reversible. CBP from Cellvibrio gilvus and Clostridium thermocellum YM4, and CDP from C. thermocellum YM4 were cloned and over-expressed in Escherichia coli. All the three enzymes showed ordered bi bi mechanism. However the orders of the substrate binding of the CBPs were different. It was found that CBP from C. gilvus strictly recognized the hydroxyl groups at positions β-1, 3, and 4 of the acceptor molecule in the reverse reaction. On the other hand, the recognition of the hydroxyl groups at positions 2 and 6 was not so strict. Three branched β-1, 4-glucosyl trisaccharides were synthesized by using the reverse reaction of C. gilvus CBP. A new substrate inhibition pattern, competitive substrate inhibition, was also found in the reverse reaction of CBP using glucose as the acceptor. Specific colorimetric quantification of cellobiose was designed by using the reaction of CBP. Cellobiose was produced from sucrose at 90% yield by a combined action of three enzymes including CBP.