Angiotensin I

Angiotensin I is a biologically inactive decapeptide released from angiotensinogen by renin. Angiotensin-converting enzyme converts it mainly into angiotensin II.

Renin: Renin is an enzyme that cleaves angiotensinogen to release angiotensin I. Renin produces angiotensin I by cutting angiotensinogen.
Peptide: A peptide is a chain of amino acids joined by peptide bonds. Angiotensin I is a ten-residue member of this molecular class.
Renin–angiotensin system: The renin–angiotensin system is a hormonal network that regulates blood pressure, fluid balance, and electrolyte balance. Angiotensin I is a short-lived intermediate in this regulatory network.
Angiotensin I(1–7): Angiotensin-(1–7) is a heptapeptide produced from angiotensin I or angiotensin II that often opposes angiotensin II effects. Its distinct sequence and signaling actions distinguish it from the decapeptide angiotensin I.
Angiotensinogen: Angiotensinogen is a circulating precursor protein from which angiotensin peptides are produced. It is the substrate that renin cleaves to form angiotensin I.
Decapeptide: A decapeptide is a peptide composed of ten amino-acid residues. Angiotensin I’s defining length is ten amino acids.
ACE inhibitor: An ACE inhibitor is a drug that blocks angiotensin-converting enzyme activity. These drugs reduce the conversion of angiotensin I into angiotensin II.
Angiotensin IV: Angiotensin IV is a hexapeptide formed by further processing of angiotensin II. It is a downstream angiotensin peptide, not the precursor that ACE converts into angiotensin II.
Angiotensin-converting enzyme: Angiotensin-converting enzyme is a peptidase that converts angiotensin I into angiotensin II. It removes two amino acids from angiotensin I to form angiotensin II.
Proteolysis: Proteolysis is the enzymatic cleavage of proteins or peptides into smaller fragments. Renin and ACE produce and process angiotensin I through peptide-bond cleavage.

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