PURIFICATION, CHARACTERIZATION AND ACCUMULATION OF 3 VIRUS-INDUCED CUCUMBER PEROXIDASES

Three anionic peroxidases (EC 1.11.1.7), named Prx1, 2, and 3, which a re rapidly accumulated in cucumber (Cucumis sativus L., cv. Laura) rea cting hypersensitively to tobacco necrosis virus, were purified to hom ogeneity. The three enzymes had an isoelectric point about 4.3, and th e relative molecular masses of Prx1, 2, and 3 estimated by SDS-PAGE we re 40 700, 38 000, and 37 100, respectively. These peroxidases had a s imilar pH stability, but differed in their specific activity, pH optim um, 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.