Which of the following amino acid residues make up the catalytic triad of chymotrypsin?

• A. Threonine, Histidine, Lysine
• B. Tyrosine, Arginine, Aspartate
• C. Serine, Cysteine, Glutamate
• D. Serine, Histidine, Aspartate

Answer: (D)

Verified step by step guidance

1. Understand the concept of a catalytic triad: A catalytic triad is a group of three amino acid residues in the active site of certain enzymes that work together to perform catalysis. In chymotrypsin, the catalytic triad consists of Serine, Histidine, and Aspartate.
2. Recognize the role of each residue in the catalytic triad: Serine acts as the nucleophile, Histidine serves as a base to activate Serine, and Aspartate stabilizes the positive charge on Histidine during catalysis.
3. Eliminate incorrect options by analyzing the amino acid properties: For example, Threonine, Lysine, and Tyrosine are not part of the catalytic triad in chymotrypsin because they do not fulfill the specific roles required for catalysis.
4. Match the correct amino acids to their roles in the catalytic triad: Serine is the nucleophile, Histidine is the base, and Aspartate stabilizes the charge. This combination is unique to the catalytic triad of chymotrypsin.
5. Confirm the correct answer: Based on the roles and properties of the amino acids, the catalytic triad of chymotrypsin is made up of Serine, Histidine, and Aspartate.