Angiotensin II (Ang II) is an octapeptide that causes marked
contraction of smooth muscle cells in blood vessels, which ultimately
may lead to development of high blood pressure (hypertension).
Ang II is formed from Angiotensin I in the blood by the Angiotensin I Converting Enzyme (ACE). ACE is a glycoprotein with
peptidyl dipeptide hydrolase activity which cleaves Angiotensin I to
produce Ang II in the blood. The powerful vasoconstrictive action of
Ang II and its stimulation of the synthesis and release of aldosterone
(which favors the retention of sodium and water) have a
consequent increase in artery pressure. ACE also hydrolyzes and
inactivates bradykinin, a peptide with a powerful vasodilatory action