A continuous spectrophotometric assay for angiotensin converting enzyme

Furanacryloyl tripeptides conforming to the known substrate specificity of the angiotensin converting enzyme (dipeptidyl carboxypeptidase, EC 3.4.15.1) have been employed to provide a continuous spectrophotometric assay for this peptidase in the visible region. The assay is based on a blue shift of the absorption spectrum that occurs upon hydrolysis of the substrate to produce a furanacryloyl-blocked amino acid and a dipeptide. Of the various furanacryloyl tripeptides tested, furanacryloyl-l-phenylalanylglyeylglycine exhibits the most suitable characteristics for routine assays of angiotensin converting enzyme.