Angiotensin ii

Angiotensin II belongs to the group of angiotensins, which form a group of peptide hormones belonging to the tissue hormones, which are formed by enzymatic cleavage by different peptidases from angiotensinogen of the liver. The primary structure of angiotensin II is that of a peptide hormone consisting of eight amino acids (octapeptide): H2N-Asp-Arg-Val-Tyr-Ile-His-Pro-Phe-COOH.

Thus, angiotensin II is cleaved in the presence of the angiotensin converting enzyme (ACE) from angiotensin I into the octapeptide angiotensin II. Angiotensin II is responsible for the vasocontrictive effect. Angiotensin II acts via two different receptors (AT1 and AT2 receptors), which are differently expressed on different tissues.

Angiotensin I itself is largely inactive.

According to their chemical structure, ACE inhibitors are dipeptide or tripeptide analogues of the C-terminal amino acid sequence of angiotensin I. They are all acids with at least one free carboxyl group, which is required for binding with the catalytic centre of the ACE. They block the function of the enzyme thereby inhibiting the conversion of angiotensin I to angiotensin II.