抄録
Prior to various enzymatic studies on thiaminase II of Bacillus aneurinolyticus, stability of the enzyme was investigated and the following results were obtained. The purified thiaminase II was considerably stable against heating and the reaction catalysed by the enzyme followed Arrhenius's equation below 53℃ and Q_<10> was 2.2 The enzyme was unstable below pH 5.5 but comparatively stable in alkaline solution. Thiaminase II, however, was unstable in solution containing chelating agents which increased the enzymatic activity. Its stability was increased by metallic ions, such as Zn^<..>. Mg^<..> or Mn^<..>, and by several reducing reagents, such as cysteine, Na_2S and Na_2SO_3. On the contrary, Cu^<..> or Co^<..> was strong inhibitor for the enzymatic activity. By the application of the above mentioned results, the inactivated enzyme was reactivated by cysteine, one of the reducing agents and Zn^<..>.
