[Molecular characteristics of the chitin-binding peroxidases of plants]

The chitin-binding ability of isoperoxidases isolated from 23 plants of different species was studied. The activation of peroxidases in a protein extract in the presence of this polysaccharide was found for 14 of the studied plants. Anionic isoperoxidases were shown to be sorbed on chitin and eluted from them with 1 M NaCl for 16 of the plant species. Cationic isoforms of the peroxidases of some species of the Fabaceae and Cucurbitaceae plant families also bound to chitin. An immunochemical similarity was found between the chitin-binding isoperoxidases of taxonomically distant plant species (the Pomaceous, Fabaceae, and gourd families). Moreover, a high homology of the molecular structures of the polysaccharide-binding sites was revealed for the anionic peroxidases of rice, wheat, oat, zucchini, cucumber, and radish. We propose the existence of a special class of plant peroxidases that bind with polysaccharides (chitin) and participate in the protective reactions of plants against pathogens.