Cell-Wall-Splitting Enzymes of Puccinia Graminis Var. Tritici

Evidence is given for the existence of a hemicellulase and a cellulase in uredospores of Puccinia graminis var. tritici. Pectinase is also present and is shown to be an adaptive enzyme. The pH and temperature optima of these three cell-wall-splilting enzymes have been determined by means of viscosimetric measurements. Preliminary investigations using the mannogalactan of Ceratonia siliqua L. as a substrate for hemicellulase and carboxymethylcellulose as a substrate for cellulase indicate that degradation with the enzymes of ungerminated rust involves attack on internal linkages of the substrate molecule, giving a rapid decrease in viscosity with slow production of free reducing groups. The influence of heavy metal salts, reducing agents, and iodoacetic acid was examined.