Endopolygalacturonase, an extracellular pectic enzyme of Rhizoctonia fragariae

A pectolytic enzyme from culture filtrates of Rhizoctonia fragariae was purified approx. 29-fold. The enzyme exhibited maximal depolymerizing activity on Na-polypectate rather than pectin at pH 5.0 and was inhibited at different extent by divalent cations Mg++, Mn++, Ca++. The analysis by paper chromatography of the products of enzyme hydrolysis suggested that the enzyme attacks the substrate by a random mechanism. The absorption spectrum of the chromogen formed by the hydrolysis products and thiobarbituric acid suggested that the enzyme is a hydrolytic enzyme. On the basis of these results the enzyme is classifiable as endo-polygalacturonase (poly alpha-1,4-galacturonide glycanohydrolase E.C. 3.2.1.15).