Purification and characterization of an endopolygalacturonase produced by Sclerotinia sclerotiorum

An endopolygalacturonase (endo-PG), was purified from the culture medium of a local isolate of Sclerotinia sclerotiorum with ammonium sulphate precipi tation, cation exchange chromatography and gel filtration. The purified end o-PG had a molecular mass of approximately 18 kDa estimated by gel filtrati on. The isoelectric point was determined by isoelectric focusing to be appr oximately 8, suggesting that PG II possesses a net positive charge at physi ological pHs. The pH optimum for the enzyme was at pH 4.5. The endo-PG show ed essentially the same affinity for pectin and polygalacturonic acid as su bstrates.