Endopolygalacturonase from Rhizoctonia fragariae: purification and characterization of two isoenzymes.

An electrophoretically homogeneous preparation of endo-polygalacturonase (poly(1,4-α-d-galacturonide)glycanohydrolase, EC 3.2.1.15) from culture filtrates of Rhizoctonia fragariae, a pathogenic agent in strawberry plants, was resolved into twoisoenzymes when subjected to isoelectrofocusing in a narrow pH range. The isoelectric points of the twoisoenzymes were 6.76 ± 0.03 and 7.08 ± 0.05. The two polygalacturonases exhibited similar substrate specificity, pH optimum and pattern of degradation of sodium polypectate. The two enzymes consisted of a sigle polypeptide chain which had an apparent molecular weight of 36 000 as determined by gel filtration on Sephadex G-100.