Cinnabarinate Synthase Activity in Normal and Acatalasemic Mice 1

Summary The introduction of the acatalasemic gene locus, Csb, which presumably affects only catalase biosynthesis, not only reduces the catalase activity of blood and liver in two inbred strains of mice, but comparably reduces the activity of cinnabarinate synthase. This enzyme converts the carcinogen hydroxyanthranilic acid to another carcinogen, cinnabarinic acid. The injection of aminotriazole, which inhibits the catalase activity of the liver but not of the blood, similarly inhibits the cinnabarinate synthase activity of the liver and not of the blood. The proteins responsible for the two enzyme activities therefore appear identical, confirming the recent suggestion of Savage and Prinz. The cinnabarinate synthase reaction can also be carried out by Cu2+ or Mn2+ in absence of any enzyme, but addition of a source of catalase or hemoglobin accelerates the reaction. Catalase or hemoglobin, in the absence of Cu2+ or Mn2+, are incapable of carrying out the oxidative dimerization of hydroxyanthranilic acid.