Biochemical confirmation and characterization of the family-57-like α-amylase ofMethanococcus jannaschii

The gene encoding a family-57-like α-amylase in the hyperthermophilic archaeonMethanococcus jannaschii, has been cloned intoEscherichia coli. Extremely thermoactive α-amylase was confirmed in partially purified enzyme solution of the recombinant culture. This enzyme activity had a temperature optimum of 120°C and a pH optimum 5.0–8.0. The amylase activity is extremely stable against denaturants. Hydrolysis of large sugar polymers with α-1–6 and α-1–4 linkages yields products including glucose polymers of 1–7 units. Highest activity is exhibited on amylose. The catalyst exhibited a half-life of 50 h at 100°C, among the highest reported thermostabilities of natural amylases.