Purification and some properties of an extracellular dextranase from Penicillium notatum

Abstract

Penicillium notatum 1 was found to produce large amounts of extracellular dextranase when grown aerobically in fermenter culture. The crude enzyme specifically hydrolysed a series of dextrans and their derivatives and showed optimal activity at pH 4·8 and 50 °C. Two highly purified fractions (dextranase I and II) were simply separated from a crude enzyme powder by sequential ion- exchange chromatography on DEAE-Sepharose, CM-Sepharose, and chromatofocusing on PBE 94 columns. Both enzymic fractions were active and catalytically similar. Dextranase I (D 1 ) was recovered with a 96-fold increase in specific activity and a yield of 48%; dextranase II (D 2 ) was purified 112-fold with a yield of 29%. The final enzyme preparations were homogeneous in polyacrylamide gel disc electrophoresis (PAGE) and high-performance liquid chromatography (hplc). The molecular weights, estimated by hplc were 55·8 kDa for D 1 and 50·1 kDa for D 2 , and their isoelectric points, established by chromatofocusing, were 4·9 and 4·75, respectively.