Biochemistry · Enzyme
Angiotensin-converting enzyme (ACE) !
ACE makes angiotensin II, which narrows vessels, and breaks down bradykinin, which widens them. ACE inhibitors block it.
Updated 2026-11-01
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Key facts
- A zinc peptidase that clips two amino acids off the C-terminal end of peptides.
- Renin–angiotensin system: angiotensin I (inactive) → angiotensin II, a strong vasoconstrictor.
- The same enzyme (kininase II) inactivates bradykinin, a vasodilator; it also cuts substance P and enkephalins.
- It sits on the outer surface of cells, anchored by one pass through the membrane; a cleaved soluble form circulates in plasma.
Structure
- The somatic form has two catalytic domains (N and C), each with its own active site and zinc ion; chloride activates it.
- Structure 1UZE is the testicular form, which has a single domain, holding enalaprilat in the active site next to the zinc.
Regulation
- Chloride ions strongly activate it.
- Angiotensin II production is mostly set upstream, by how much renin the kidney releases.
Inhibitors and toxins
- ACE inhibitors (enalapril): enalapril is a prodrug; hydrolysis of its ester gives enalaprilat, the active inhibitor.
Clinical notes
- Less angiotensin II widens vessels and lowers aldosterone: ACE inhibitors treat high blood pressure and heart failure, and protect the kidney in diabetes.
- A persistent dry cough is reported with all ACE inhibitors and is usually attributed to bradykinin that is no longer broken down; angioedema (face, lips, tongue, larynx) is rare.
- Potassium can rise, especially with kidney disease or potassium-sparing drugs.
- These drugs are stopped as soon as pregnancy is detected: they can harm the fetus.
Drugs that act here
Related conditions
Test yourself
Think of the answer, then tap the question to see it.
Which two peptides does ACE handle, with opposite effects on vessels?
It makes angiotensin II (vasoconstrictor) from angiotensin I and inactivates bradykinin (vasodilator).
Which metal sits in the ACE active site?
Zinc; ACE inhibitors such as enalaprilat bind next to it.
Why is enalapril called a prodrug?
It is inactive until its ester is cut, giving enalaprilat, the form that inhibits ACE.
Which ACE-inhibitor adverse effect is linked to bradykinin?
Dry cough and, rarely, angioedema.
Educational information, not medical advice. For any symptom, see a health professional.
Sources: ACE: Angiotensin-converting enzyme (human) (UniProt, 2026); 1UZE: Complex of the anti-hypertensive drug enalaprilat and the human testicular angiotensin I-converting enzyme (RCSB Protein Data Bank, 2026); ENALAPRIL MALEATE tablet (DailyMed, US National Library of Medicine, 2026); Enalapril: MedlinePlus Drug Information (MedlinePlus, US National Library of Medicine, 2026).
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