Angiotensin 1/2 (5-7), (C17H27N5O4), a peptide with the sequence H2N-Ile-His-Pro-OH, MW=365.43. Angiotensin is a peptide hormone that causes vasoconstriction and a subsequent increase in blood pressure. Angiotensin is an oligopeptide and is a hormone and a powerful dipsogen. It is derived from the precursor molecule angiotensinogen, a serum globulin produced in the liver. It plays an important role in the renin-angiotensin system1. Angiotensin I is formed by the action of renin on angiotensinogen. Renin is produced in the kidneys in response to renal sympathetic activity, decreased intrarenal blood pressure at the juxtaglomerular cells2, or decreased delivery of Na+ and Cl- to the macula densa3.If less Na+ is sensed by the macula densa, renin release by juxtaglomerular cells is increased.Renin cleaves the peptide bond between the leucine (Leu) and valine (Val) residues on angiotensinogen, creating the ten-amino acid peptide (des-Asp) angiotensin I Angiotensin I appears to have no biological activity and exists solely as a precursor to angiotensin 2.
References:
1. Basso N, Terragno NA (December 2001). "History about the discovery of the renin-angiotensin system". Hypertension 38 (6): 1246–9.
2. Skurk T, Lee YM, Hauner H (May 2001). "Angiotensin II and its metabolites stimulate PAI-1 protein release from human adipocytes in primary culture". Hypertension 37 (5): 1336–40.
3. Williams GH, Dluhy RG (2008). "Chapter 336: Disorders of the Adrenal Cortex". In Loscalzo J, Fauci AS, Braunwald E, Kasper DL, Hauser SL, Longo DL. Harrison's principles of internal medicine. McGraw-Hill Medical.