Production, purification and partial characterization of an endo-polygalacturonase from Cryptococcus albidus var. albidus

Abstract

Cryptococcus albidus var. albidus produced an extracellular endo-polygalacturonase (poly (1,4-alpha-D-galacturonide) glycanohydrolase EC 3.2.1.15) when grown in a synthetic medium containing one of a variety of pectic substances or galacturonic acid. The highest level of enzyme activity (15.5 VU X ml-1) was obtained after 72 h of growth on 1.0% low-methoxyl pectin. The enzyme, purified by gel filtration (Sephadex G-100) after repeated ammonium sulphate precipitation and dialysis, showed only one band by polyacrylamide gel electrophoresis and had the following properties: mol wt (MWr) 41000 dal; isoelectric point (pI) = 8.10 +/- 0.10; optimum temperature and pH for activity around 37 degrees C and pH 3.75, respectively; pH stability in the pH range 4.0 to 8.0; complete heat inactivation after 10 min at 55 degrees C; Km and Vmax values 5.7 X 10(-1) mg X ml-1 and 5.1 X 10(-1) mmoles X min-1, respectively.