Abstract

α-Methyldopa stimulates the conversion of the primary catalase-peroxide complex (Compound I) to the catalytically inactive secondary catalase-peroxide complex (Compound II) in solutions of purified catalase as well as in suspensions of isolated hepatocytes. The rate of Compound II formation is dependent upon both the rate of H₂O₂ generation and the concentration of α-methyldopa. The catalase-dependent oxidation of α-methyldopa to the corresponding dihydroxyindole nucleus occurs much more rapidly than the formation of Compound II and suggests that the catalase-dependent one-electron oxidation of α-methyldopa may initiate a free radical process. These reactions may be important in α-methyldopa-induced hepatotoxicity.