Characterization Of A Thermostable Glucose Dehydrogenase With Strict Substrate Specificity From A Hyperthermophilic Archaeon Thermoproteus Sp. Gdh-1

A hyperthermophilic archaeon was isolated from a terrestrial hot spring on Kodakara Island, Japan and designated as Thermoproteus sp. glucose dehydrogenase (GDH-1). Cell extracts from cells grown in medium supplemented with glucose exhibited NAD(P)-dependent glucose dehydrogenase activity. The enzyme (TgGDH) was purified and found to display a strict preference for d-glucose. The gene was cloned and expressed in Escherichia coli, resulting in the production of a soluble and active protein. Recombinant TgGDH displayed extremely high thermostability and an optimal temperature higher than 85 degrees C, in addition to its strict specificity for d-glucose. Despite its thermophilic nature, TgGDH still exhibited activity at 25 degrees C. We confirmed that the enzyme could be applied for glucose measurements at ambient temperatures, suggesting a potential of the enzyme for use in measurements in blood samples.