Purification,characterization and accumulation of three virus-induced cucumber peroxidases

Three anionic peroxidases (EC 1.11.1.7), named Prx1, 2, and 3, which are rapidly accumulated in cucumber (Cucumis sativus L., cv. Laura) reacting hypersensitively to tobacco necrosis virus, were purified to homogeneity. The three enzymes had an isoelectric point about 4.3, and the relative molecular masses of Prx1, 2, and 3 estimated by SDS-PAGE were 40 700, 38 000, and 37 100, respectively. These peroxidases had a similar pH stability, but differed in their specific activity, pH optimum, and thermal stability By Ouchterlony double diffusion tests with antisera raised against the three purified enzymes, close serological relationships have been demonstrated between the three peroxidases.