Separation and purification of N-domain of bovine lung angiotensin I-converting enzyme by size exclusion chromatography

Bovine lung angiotensin I-converting enzyme is a monomer with two active si tes, in its two (N and C) homologous domains. A process is described for th e preparative isolation of the ACE N-domain to either the ACE soluble monom er or ACE aggregated one. After exposure to moderate heat for 7 hours and i n presence of a protease, ACE N-domain was obtained as a whole, and only fr agments of the C-domain. N-domain purified was separated by Sephacryl S-300 HR chromatography, and a recovery of 80% was obtained. Molecular mass was estimated to be 100 kDa by sodium dodecyl sulfate gel electrophoresis. Afte r purifying and partially sequencing this domain, we have investigated some catalytic properties and the inhibition by captopril.