Isolation of angiotensin-converting enzyme inhibitor from porcine plasma

An inhibitory peptide of angiotensin-converting enzyme was purified from porcine plasma. The final preparation showed IC50 values of 4.2, 0.6, and 0.9 microgram/ml for angiotensin-converting enzymes from guinea pig serum, rabbit lung, and monkey brain, respectively. The amino acid sequence of the inhibitor was determined as leucyl-valyl-leucine by Edman procedure. This structural observation was supported by mass spectrometric analysis.