Peptides that inhibit angiotensin-converting enzyme (ACE) were isolated from α-zein hydrolysate prepared with thermolysin. Their chemical structures were identified by Edman degradation and fast-atom bombardment mass spectrometry. Most of them were found to be tripeptides such as Leu-Arg-Pro, Leu-Ser-Pro, and Leu-Gin-Pro, having IC50 values of 0.27, 1.7, and 1.9μM, respectively. These peptides were synthesized by a solid phase procedure and had similar ACE inhibitory activities as the isolated inhibitors. The hypotensive activity of Leu-Arg-Pro on spontaneously hypertensive rats was also investigated, with the result that the blood pressure decreased by 15mmHg after a 30mg/kg intravenous injection.
Japan Society for Bioscience, Biotechnology, and Agrochemistry