Short communication: Measuring the angiotensin-converting enzyme inhibitory activity of an 8-amino acid (8mer) fragment of the C12 antihypertensive peptide

An eight amino acid fragment (PFPEVFGK) of a known milk protein-derived antihypertensive peptide was synthesized by microwave-assisted solid phase peptide synthesis and purified by reverse phase HPLC. Its ability to inhibit the angiotensin-converting enzyme was assessed and compared to that of the parent 12mer peptide (FFVAPFPEVFGK) to determine the effect of truncating the sequence on the overall hypotensive activity. The activity of the truncated 8mer peptide was found to be almost 1.5 times less active than the 12mer, with IC(50) values of 108 and 69 uM, respectively. The overall activities of both the 12mer and the 8mer, however, are in the range of being physiologically important and potentially active following oral administration, and therefore may have potential use as a blood pressure lowering agent in humans in the future.