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 af finity and size exclusion chromatography. The affinity purified enzyme was solubilized by tryptic attack for 1 h at 300C and separated by Se phacryl S-300 HR chromatography. A recovery of 68% was obtained. The p urification procedure described here, enables one to obtain 27 mg of e nzyme with a specific activity of 26 min(-1) mg(-1) from 1 kg of bovin e lung. Molecular mass of native soluble ACE form was obtained by size -exclusion high performance liquid chromatography. Molecular mass of m embrane-bound enzyme and the ACE form solubilized with trypsin, was fo und to be 170 kDa and 160 kDa, respectively, using disc gel electropho resis in the presence of sodium dodecyl sulfate.