Question:medium
Alpha-1 antitrypsin works by which of the following mechanisms?
Alpha-1 antitrypsin works by which of the following mechanisms?
Show Hint
Its deficiency causes emphysema because this lung protease runs unchecked.
Updated On: Jun 23, 2026
- Inhibition of trypsin
- Inhibition of trypsinogen
- Inhibition of elastase
- Inhibition of chymotrypsin
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: Approach by clinical consequence: A1AT deficiency causes emphysema, so the enzyme it normally curbs must damage lung tissue.
Step 2: That lung-damaging enzyme is neutrophil elastase, which chews up elastin in alveolar walls.
Step 3: A1AT, a liver-made serpin, binds and neutralises elastase, keeping the protease-antiprotease balance in favour of intact connective tissue.
Step 4: When A1AT is low, elastase runs free and panacinar emphysema follows. The mechanism asked is inhibition of elastase, not trypsin, trypsinogen or chymotrypsin.
\[\boxed{\text{Inhibition of elastase}}\]
Step 2: That lung-damaging enzyme is neutrophil elastase, which chews up elastin in alveolar walls.
Step 3: A1AT, a liver-made serpin, binds and neutralises elastase, keeping the protease-antiprotease balance in favour of intact connective tissue.
Step 4: When A1AT is low, elastase runs free and panacinar emphysema follows. The mechanism asked is inhibition of elastase, not trypsin, trypsinogen or chymotrypsin.
\[\boxed{\text{Inhibition of elastase}}\]
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