Multiple Choice
Which amino acids in chymotrypsin's active site are critical participants in the cleavage of the substrate?
8. Protein Function
Chymotrypsin
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Which of the following statements about chymotrypsin is true?
A
Chymotrypsin requires a metal ion cofactor for its catalytic activity.
B
Chymotrypsin is most active at acidic pH (below 4).
C
Chymotrypsin is a serine protease that cleaves peptide bonds on the carboxyl side of aromatic amino acids.
D
Chymotrypsin hydrolyzes only peptide bonds adjacent to basic amino acids.
Verified step by step guidance1
Step 1: Understand the role of chymotrypsin. Chymotrypsin is an enzyme classified as a serine protease, meaning it uses a serine residue in its active site to catalyze the hydrolysis of peptide bonds.
Step 2: Recall the specificity of chymotrypsin. Chymotrypsin specifically cleaves peptide bonds on the carboxyl side of aromatic amino acids such as phenylalanine, tyrosine, and tryptophan. This specificity is due to the structure of its active site, which accommodates aromatic side chains.
Step 3: Evaluate the statement about metal ion cofactors. Chymotrypsin does not require a metal ion cofactor for its catalytic activity. Instead, it relies on a catalytic triad (serine, histidine, and aspartate) to perform its function.
Step 4: Assess the pH activity range. Chymotrypsin is most active at a slightly alkaline pH (around 7.8-8.0), not at acidic pH (below 4). Acidic conditions would denature the enzyme and impair its function.
Step 5: Eliminate incorrect statements and confirm the correct one. Based on the above points, the correct statement is: 'Chymotrypsin is a serine protease that cleaves peptide bonds on the carboxyl side of aromatic amino acids.'
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