In response to lowered blood pressure, the renin enzyme cleaves angiotensin-1 from angiotensin. Angiotensin-converting enzyme (ACE) then removes a dipeptide to yield the physiologically active peptide angiotensin-2, the most potent pressor substance known, which helps regulate volume and mineral balance of body fluids.Canine, rat: H-Asp-Arg-Val-Tyr-Ile-His-Pro-OH or H-DRVYIHP-OH