AN EXTRACELLULAR PROTEASE OF THE MICROMYCETE ALTERNARIA-ALTERNATA

An extracellular protease was isolated from the mycelial fungus Altern aria alternata. The enzyme was purified 1300-fold with a yield of 8.3% by affinity chromatography and gel filtration. The molecular weight o f the purified protease is 33 kD. The enzyme is maximally active at 48 degrees C and pH 8.0 and 9.1 with BAPA and casein as substrates, resp ectively, is stable below 30 degrees C, and rapidly loses activity at higher temperature. Based on its inhibitor sensitivity, the extracellu lar protease of A. alternata can be classified as a serine protease. T he substrate specificity of the enzyme is characteristic of trypsin-li ke proteases.