Hypertension (high blood pressure) is a major human disease and despite much research, the problem is still not completely understood. A major part of the problem involves the action of an octapeptide, angiotensin II. This peptide hormone stimulates the constriction of blood vessels which leads to an increase in blood pressure. Angiotensin II is produced by the removal of two amino acids units on angiotensin I by an enzyme in the blood. Angiotensin I does not constrict blood vessels.
QUES. What is the difference between angiotensin I and angiotensin II? This difference is responsible for difference in physiological action.
Angiotensin I: asp - arg - val - tyr - ile - his - pro - phe - his - leu
Angiotensin II: asp - arg - val - tyr - ile - his - pro - phe.
- Charles Ophardt, Professor Emeritus, Elmhurst College; Virtual Chembook