Question

Which of the following amino acids contain(s) two chiral carbons?

• A. L-Leucine
• B. L-Threonine
• C. L-Isoleucine
• D. L-Asparagine

Hint:

Amino acids with two chiral centers are less common. Recognizing chirality is important for understanding molecular asymmetry and its impact on protein structure.

Answer 1

The Correct Option is B, C

Step 1: Understand chirality in amino acids.
A chiral carbon is a carbon atom that is attached to four different groups. Amino acids with two chiral centers have two such carbon atoms in their structure.

Step 2: Analyze the amino acids.

• L-Leucine (A): Leucine has only one chiral carbon (the alpha carbon). Its side chain is not branched in a way that introduces a second chiral center. ✅ Only one chiral center.
• L-Threonine (B): Threonine has two chiral centers: one at the alpha carbon and another at the beta carbon (side chain), which is attached to OH, H, and CH₃. ✅ Two chiral centers.
• L-Isoleucine (C): Isoleucine also has two chiral centers: one at the alpha carbon and another at the beta carbon (side chain), which is branched. ✅ Two chiral centers.
• L-Asparagine (D): Asparagine has only one chiral center at the alpha carbon; the side chain does not introduce a second chiral carbon. ❌ Only one chiral center.

Step 3: Conclusion.
The amino acids with two chiral carbons are:
(B) L-Threonine and (C) L-Isoleucine.

Final Answer:
The correct answer is (B), (C).