Peroxidase-Generated Hydrogen Peroxide as a Source of Antifungal Activity In Vitro and on Tobacco Leaf Disks

Abstract

Hydrogen peroxide was generated in vitro by horseradish peroxidase in the presence of NADH or NADPH. When peroxidase was inactivated by heating (30 min at 100 C) or catalase was added to the reaction mixture, little or no hydrogen peroxide was generated as measured by a guaiacol oxidation assay. In the absence of either H 2 O 2 or peroxidase, guaiacol was also not oxidized. Guaiacol oxidation was also observed when either NADH was replaced by NAD and malate in the presence of malate dehydrogenase or NADPH was replaced by NADP and glucose-6-phosphate in the presence of glucose-6-phosphate dehydrogenase (...)