Thermostable hydantoinase from a hyperthermophilic archaeon, Methanococcus jannaschii

A hyperthermophilic hydantoinase from Methanococcus jannaschii with an optimum growth at 85°C was cloned and expressed in E. coli. The recombinant hydantoinase was purified by affinity and anion-exchange chromatography and determined to be homotetrameric protein by gel filtration chromatography. The best substrate for the hydantoinase was D,L-5-hydroxyhydantoin, which has the specific activity of 183.4 U/mg. The optimum pH and temperature for the hydantoinase activity was 8.0 and 80°C, respectively. The half-life of the hydantoinase was measured to be 100 min at 90°C in the buffer containing 500 mM KCl. Manganese ions were the most effective for the hydantoinase activity. Stereospecificity was determined to be L-specific for the 5-hydroxymethylhydantoin and 5-methylhydantoin by chiral TLC. The activity yields as well as the operational stabilities of the thermostable M. jannaschii hydantoinase could be significantly improved by immobilization method.