Purification and characterisation of galactose-induced pectinases from the exo-1 mutant strain of Neurospora crassa

Pectinases produced by the exo-1 mutant of N. crassa in galactose plus glucose supplemented medium, were separated by ion-exchange chromatography into two pools. Pool I contained pectate and pectin lyases, and variable polygalacturonase activity. Pool 2 contained polygalacturonase activity only. Gel filtration indicated a MWapp of 80 kDa (higher than those of separate enzymes) for all activities in the first pool, suggesting a complex. Polygalacturonase, pectin and pectate lyases were purified 39-fold, 22-fold and 33-fold, respectively. Optima of temperature and pH were 45 degrees C and 5.5 for polygalacturonase activity and 50 degrees C and 9.5 for lyase activities. Km and Vmax values for polygalacturonase were 0.023 mg polypectate/ml and 2.08 mu moles (reducing sugar)/min/mg protein.