The maturation mechanisms of subtilisins, Tk-subtilisin and Tk-SP, from the hyperthermophilic archaeon Thermococcus kodakarensis were analyzed. The results indicate that both proteins are activated(matured) upon autoprocessing and degradation of N-terminal propeprides, folding of Tk-subtilisin is induced upon binding of the Ca^<2+> ions to the Ca^<2+>-binding loop, Tk-SP is matured in the absence of the Ca^<2+> ions, Tk-SP requires C-terminalβ-jelly roll domain for hyperstability. It was also shown that Tk-subtilisin is useful for degradation of abnormal prion proteins.
