Purification and characterization of ovine pancreatic elastase

Elastase was isolated from ovine pancreas and purified to homogeneity by two different procedures. One involved precipitation with ammonium sulphate, p-aminobenzamidine-Sepharose chromatography, CM-Sepharose ion exchange chromatography and S-300 Sephacryl chromatography. The other involved the direct adsorption of elastase by tri-L-alanyl-Sepharose chromatography and a CM-Sepharose step. The enzyme, which was produced in an inactive form in the pancreas, was activated with a trace of trypsin prior to chromatography. Ovine pancreatic elastase has an isoelectric point above pI 9.3 and its molecular mass is estimated at approximately 25 kDa. The optimal pH range for activity is between 8.0 and 8.4 and the enzyme is unstable at pH below 4.0 and above 10.0 and at temperatures above 65 degrees C. The kinetic properties of the enzyme were determined with succinyl-Ala-Ala-Ala-p-nitroanilide as the substrate. Km and kcat Km-1 proved to be similar to the kinetic parameters of porcine elastase determined simultaneously.