Question:easy
Which of the following is a serine protease?
Which of the following is a serine protease?
Show Hint
Look for the enzyme with a Ser-His-Asp catalytic triad, not the acid or zinc protease.
Updated On: Jun 24, 2026
- Pepsin
- Trypsin
- Carboxypeptidase
- None
Show Solution
The Correct Option is B
Solution and Explanation
Step 1: Match each enzyme to its mechanistic class and find the one whose catalysis depends on an active-site serine.
Step 2: Trypsin fits exactly. As a pancreatic serine protease it relies on the Ser-His-Asp catalytic triad, with serine performing the nucleophilic attack on the peptide carbonyl, and it preferentially cuts after arginine and lysine.
Step 3: The distractors fall into different families. Pepsin is an aspartic protease active in the acidic stomach, and carboxypeptidase is a zinc metalloexopeptidase that trims terminal residues. Neither employs a serine nucleophile.
Step 4: Among chymotrypsin-like enzymes, trypsin is the textbook serine protease, so it is the correct answer.
\[\boxed{\text{Trypsin}}\]
Step 2: Trypsin fits exactly. As a pancreatic serine protease it relies on the Ser-His-Asp catalytic triad, with serine performing the nucleophilic attack on the peptide carbonyl, and it preferentially cuts after arginine and lysine.
Step 3: The distractors fall into different families. Pepsin is an aspartic protease active in the acidic stomach, and carboxypeptidase is a zinc metalloexopeptidase that trims terminal residues. Neither employs a serine nucleophile.
Step 4: Among chymotrypsin-like enzymes, trypsin is the textbook serine protease, so it is the correct answer.
\[\boxed{\text{Trypsin}}\]
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