Multiple forms of chitosanase activities

Leaf, seed and fruit crude extracts from several species were tested for chitosanase activity using a polyacrylamide gel assay. Chitosanase activity was found in higher and in lower plant species. Depending on extracts, one to six acidic isoforms and one to three basic isoforms could be detected. In general, seeds and fruits seem to be the best sources of chitosanase activity. Triticum aestivum and Hordeum vulgare seeds were the best sources of chitosanases from monocotyledons while Pisum sativum seeds and Cucumis sativus fruits were the best sources for dicotyledons. The apparent molecular mass of some chitosanases was evaluated for eight plant species: Onoclea sensibilis, Abies balsamea, Thuya occidentalis, Cucumis sativus, Pisum sativum, Solanum melongena, Triticum aestivum and Setaria italica. Chitosanases had apparent Mr s between 10 000 and 23 000 after sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) without a reducing agent. Most chitosanases were completely inhibited by 2-mercaptoethanol in the sample buffer before SDS-PAGE. However, some chitosanase activity could be revealed in some extracts after exposure to 2-mercaptoethanol. With the O. sensibilis extract, one chitosanase denatured by SDS alone migrated as an Mr 21 000 protein and as an Mr 33 000 protein when previously reduced with 2-mercaptoethanol.