Purification and Characterization of a Novel Phosphorylase, Kojibiose Phosphorylase, from Thermoanaerobium brockii

Abstract

The thermophilic anaerobe Thermoanaerobium brockii ATCC 35047 produces a novel phosphorylase, kojibiose phosphorylase, which catalyzes the reversible phosphorolysis of kojibiose to form β-glucose 1-phosphate and D-glucose. The enzyme was purified from a cell-free extract to an electrophoretically homogeneous state by successive column chromatography on DEAE-Toyopearl 650S, CM-Toyopearl 6505, Hydroxyapatite, Ultrogel AcA44, Mono Q, and Butyl-Toyopearl 650 M . The enzyme had a molecular weight of 83, 000 by SDS-polyacrylamide gel electrophoresis and a pl of 4 .3 to 4.4 by gel isoelectrofocusing. The enzyme showed the highest activity at pH 5 .5 and 65°C, and was stable from pH 5.5 to 9.7 and up to 65°C. The enzyme activity was inhibited by Hg²⁺ and Pb²⁺⁰. The Km values for kojibiose, Pi, glucose, and β-glucose 1-phosphate were 0 .77, 0.85, 3.52, and 0.77 mM, respectively.