Purification and characterization of glucose isomerase from a thermophilic bacterium, Geobacillus thermodenitrificans TH2

In the present study, the D-glucose/D-xylose isomerase was purified from a thermophilic bacterium, Geobacillus thermodenitrificans TH2, by using a Q-Sepharose ion exchange column and characterized. The purified enzyme was observed as a single band on native polyacrylamide gel electrophoresis. In the presence of D-glucose as a substrate, the optimum temperature and pH of the enzyme were found to be 80 °C and 7.5, respectively. The purified enzyme was extremely stable, in pH 7,5 and 9,0 after 72 hour incubation at 4 °C and 50 °C. When the thermal stability profile of the purified enzyme was analyzed, it was determined that the enzyme was extremely stable 4 months and 4 days at 4 °C and 50 °C, respectively. The Km and Vmax values of the purified enzyme were calculated as 32 mM and 4,684U/mg protein, respectively, from the Lineweaver-Burk plot. Additionally, it was detected that some metal ions affect the enzyme activity at different rates. As a result, D-glucose isomerase from G. thermodenitrificans TH2 has similar features with the literature.