Question

The catalytic triad of Chymotrypsin is composed of

• A. Asp, Ser, His
• B. Arg, Ser, His
• C. Glu, Thr, Lys
• D. Glu, Asp, Tyr

Hint:

The catalytic triad is critical for the action of serine proteases like chymotrypsin. The three residues — Asp, Ser, His — work together to break down proteins by cleaving peptide bonds.

Answer 1

The Correct Option is A

Step 1: Understand the catalytic triad of chymotrypsin.
Chymotrypsin is a serine protease, meaning it uses a serine residue in its active site to break peptide bonds. It has a catalytic triad, which is a set of three amino acids that work together to activate the serine residue for nucleophilic attack on the peptide bond.

Step 2: Identify the amino acids in the catalytic triad.
The catalytic triad of chymotrypsin consists of:

• Aspartate (Asp): Stabilizes the histidine and helps to deprotonate it.
• Serine (Ser): The nucleophile that attacks the peptide bond.
• Histidine (His): Acts as a base to deprotonate the serine.

Step 3: Evaluate the options.

• Option (1) Asp, Ser, His — Correct. This is the correct catalytic triad of chymotrypsin.
• Option (2) Arg, Ser, His — Incorrect, arginine is not part of the catalytic triad.
• Option (3) Glu, Thr, Lys — Incorrect, these residues do not form the catalytic triad of chymotrypsin.
• Option (4) Glu, Asp, Tyr — Incorrect, these amino acids do not make up the triad for chymotrypsin.

Step 4: Conclusion.
The catalytic triad of chymotrypsin is composed of Aspartate, Serine, and Histidine.