Synthesis of [ 14 C]Cellobiose with Clostridium thermocellum Cellobiose Phosphorylase

Cellobiose labeled either at the reducing end (4-O-beta-d-glucopyranosyl-d-[U-C]glucopyranose) or at the nonreducing end (4-O-beta-d-[U-C]glucopyranosyl-d -glucopyranose) was synthesized with Clostridium thermocellum cellobiose phosphorylase at greater than 98% purity. The radioactive cellobioses were identical to authentic cellobiose in melting point, optical rotation, isotopic dilution, and chromatographic properties.