Preparative isolation of a soluble form of bovine lung angiotensin converting enzyme by affinity and size exclusion chromatography

A high capacity process is described for the preparative purification of a soluble form of bovine lung angiotensin I-converting enzyme by affinity and size exclusion chromatography. The affinity purified enzyme was solubilized by tryptic attack for 1 h at 300C and separated by Sephacryl S-300 HR chromatography. A recovery of 68% was obtained. The purification procedure described here, enables one to obtain 27 mg of enzyme with a specific activity of 26 min(-1) mg(-1) from 1 kg of bovine lung. Molecular mass of native soluble ACE form was obtained by size-exclusion high performance liquid chromatography. Molecular mass of membrane-bound enzyme and the ACE form solubilized with trypsin, was found to be 170 kDa and 160 kDa, respectively, using disc gel electrophoresis in the presence of sodium dodecyl sulfate.