Question

In a protein, trypsin catalyzes the hydrolysis of peptide bonds with carbonyl group contributed by

• A. glutamine
• B. asparagine
• C. lysine
• D. arginine

Hint:

Trypsin cleaves peptide bonds specifically after the basic amino acids lysine and arginine, unless followed by proline.

Answer 1

The Correct Option is C, D

Step 1: Understand the role of trypsin.
Trypsin is a proteolytic enzyme that hydrolyzes peptide bonds in proteins during digestion. It is a highly specific serine protease.

Step 2: Recall the specificity of trypsin.
Trypsin specifically cleaves peptide bonds at the carboxyl side of basic amino acids.
The major amino acids recognized by trypsin are:
\[ \text{Lysine (Lys)} \quad \text{and} \quad \text{Arginine (Arg)} \]

Step 3: Understand the meaning of carbonyl group contribution.
The peptide bond hydrolyzed by trypsin has its carbonyl group contributed by lysine or arginine residues.
That means cleavage occurs after these amino acids in the peptide chain.

Step 4: Analyze glutamine.
Glutamine is a neutral polar amino acid and is not specifically recognized by trypsin for cleavage.
Hence, option (A) is incorrect.

Step 5: Analyze asparagine.
Asparagine is also a neutral polar amino acid and is not a preferred cleavage site for trypsin.
Therefore, option (B) is incorrect.

Step 6: Analyze lysine and arginine.
Both lysine and arginine possess positively charged basic side chains, making them the specific targets for trypsin-mediated peptide bond hydrolysis.
Thus, options (C) and (D) are correct.

Step 7: Final conclusion.
Therefore, trypsin hydrolyzes peptide bonds with carbonyl groups contributed by
\[ \boxed{\text{lysine and arginine}} \]
Hence, the correct answers are options (C) and (D).