抄録
Tryptophan oxygenase was become to be activated fully by low concentration of ascorbic acid after catalase was eliminated from tryptophan oxygenase fraction. Furthermore, tryptophan oxygenase free from catalase was inhibited by the addition of high concentration of ascorbic acid. The activation was dependent upon the increase of V_<max>. On the other hand, the inhibition of tryptophan oxygenase by the addition of high concentration of ascorbic acid showed competitive type. This mechanism would be dependent upon the coordination of ascorbic acid to heme-iron, because ascorbic acid could coordinate with iron ion and hematin and o-phenanthroline, a chelator as Fe^<2+>, could competitively inhibited tryptophan oxygenase. Interestingly, ascorbic acid and o-phenanthroline could not inhibit tryptophan oxygenase to which catalase was added. This fact suggests that tryptophan oxygenase forms a complex enzyme with catalase.
