Purification of Geotrichum candidum endopolygalacturonase from culture and from host tissue by affinity chromatography on cross-linked polypectate

A homogeneous endopolygalacturonase preparation was obtained from culture filtrates of Geotrichum candidum by a single-step purification, using affinity chromatography on cross-linked polypectate. The enzyme has a molecular weight of 38 000, an isoelectric point at pH 7·8, and a K_m of 1·33 mg ml⁻¹ with sodium polypectate as the substrate. The purified enzyme, at pH 4·2, macerated the albedo of lemon peel and produced typical sour rot symptoms when injected into lemon peel. An endopolygalacturonase was purified from sour rot infected tissue which was identical with the enzyme obtained from culture filtrate as judged by isoelectric focusing, SDS polyacrylamide gel electrophoresis and antigenic properties.