Purification and Characterization of Rice Peroxidasesf

Four peroxidase components, named RP-2, 4, 6, and 7, were isolated from rice (Oryza sativa L.) green leaves. Isoelectric focusing indicated that each preparation was homogeneous. The molecular weights of RP-2, 4, 6, and 7 estimated by SDS-PAGE were 48,000, 48,000, 40,000, and 39,500, and their isoelectric points were 5.4, 8.1, 9.3, and 9.2, respectively. The activity of every preparation was maximumaround pH 5.0. Antisera against these purified enzymes were raised in rabbits. Ouchterlony double diffusion tests with these antisera suggested that RP-6 and 7 were immunochemically identical and RP-2 and 4 were identical in parts and that RP-6 and 7 were quite different from RP-2 and 4. Analysis of the N-terminal amino acid sequences also showed that these peroxidase componentswere classified into two groups. The polymerase chain reaction showedthat RP-2 and/or RP-4 contained an active central region, which is homologous to other plant peroxidases.