Zinc, angiotensin I-converting enzyme and hypertension

Angiotensin-converting enzyme, or kininase II, is a zinc metallo-enzyme; the cation forms part of its active site. The enzyme transforms angiotensin I into angiotensin II and hydrolyses bradykinin into inactive peptides. Antihypertensive diuretics may decrease the activity of the angiotensin-converting enzyme by increasing urinary zinc excretion. Captopril inhibits the angiotensin-converting enzyme, but also affects electrolyte excretion and should be reassessed as a possible first-choice antihypertensive agent in the treatment of essential hypertension.