Angiotensin-I converting enzyme inhibitory peptide derived from porcine skeletal muscle myosin and its antihypertensive activity in spontaneously hypertensive rats.

Crude myosin light chain was extracted from Japanese domestic pork loin and digested with pepsin. Antihypertensive peptide was isolated from this digest as a measure of its inhibitory activity for angiotensin-I converting enzyme (ACE). Through isolation with some chromatographies, a single active fraction was isolated, and it was detected as an octapeptide, Val-Lys-Lys-Val-Leu-Gly-Asn-Pro, from 47th to 54th positions of myosin light chain. The 50% inhibitory concentration of this peptide was 28.5 muM. Kinetic evaluation showed that this peptide was a noncompetitive inhibitor, but it was slowly hydrolyzed by ACE. At the dose of 10 mg/kg, this peptide showed antihypertensive activity after a maximum of 3 h of administration and was estimated as a temporally effective hypotensor.