Release of peroxidase from soybean hypocotyl cell walls by Sclerotium rolfsii culture filtrates

Abstract

Up to 24% of the peroxidase of purified cell walls of soybean hypocotyls was released by incubation of cell walls with hydrolytic enzymes secreted by the fungus Sclerotium rolfsii. This estimate is based on comparison of peroxidase activity recovered in the medium with peroxidase activity in unincubated cell walls, estimated by a new assay. The peroxidase-release reaction occurs at 0 °C at half the rate at 30 °C. The peroxidase-release reaction occurs almost equally fast in the pH range of 3.5 to 8.0. The release of peroxidase from cell walls cannot be attributed solely to arabanase, polygalacturonase, or cellulase in the culture filtrate, although on Sephadex G-75 chromatography these activities overlap the peroxidase-releasing activity. Culture filtrate released less than 5% of the hydroxyproline protein of the cell walls.