FRACTIONATION AND CHARACTERIZATION OF 2 FORMS OF PEROXIDASE FROM ORYZA-SATIVA

Peroxidase (E.C. 1.11.1.7., hydrogen donor oxidoreductase) is widely d istributed and has been isolated from many higher plants (1). The wide distribution of the enzyme suggests that it could be of great biologi cal importance. However the role that it plays in metabolism is not cl ear due to the large number of reactions it catalyzes and the consider able number of isozymic species (2). In tomato plants, Evans and Aldri dge (3) separated out six isoperoxidases and in a later paper Evans re ported 12 isoperoxidases from tomato shoots (4). A homogeneous tomato fruit peroxidase isozyme was obtained by Jen et al. (5) using hydropho bic chromatography. Isozymes were not detected in Euphorbia characias peroxidase (6), in Ipomoea batatas peroxidase (7) and in Hordeum vulga re peroxidase (8). The simultaneous presence of Cu (II) amine oxidase and peroxidase in cell walls suggests that the peroxide generated on o xidation of the amines could be utilized by the peroxidase (6,8,9). In the graminea Oryza sativa, widely distributed, an FAD amine oxidase i s present that oxidizes diamines (10). In this plant we also found two isoperoxidases called perox I and II. Only perox I was purified to ho mogeneity and its enzymatic, physical and chemical properties have bee n studied.