Question

\( x \) is a peptide which is hydrolyzed to 2 amino acids \( y \) and \( z \). \( y \) when reacted with HNO\(_2\) gives lactic acid. \( z \) when heated gives a cyclic structure as below: 

• A. Alanine and Lysine
• B. Alanine and Glycine
• C. Glycine and Alanine
• D. Valine and Glycine

Hint:

Lactic acid formation upon reaction with HNO\(_2\) typically suggests the presence of Glycine, while the ability to form a cyclic structure upon heating points to Alanine.

Answer 1

The Correct Option is B

We are given that the peptide \( x \) hydrolyzes into two amino acids \( y \) and \( z \), where: 1. \( y \) reacts with HNO\(_2\) to form lactic acid. This indicates that \( y \) contains a primary amine group, and the reaction with nitrous acid typically results in the formation of a carboxylic acid (lactic acid). The most likely candidate for \( y \) is Glycine, as it has a simple structure and reacts with HNO\(_2\) to give lactic acid. 2. \( z \) forms a cyclic structure upon heating. This suggests that \( z \) is an amino acid that can cyclize, and Alanine is the most probable candidate since it can form a cyclic structure like proline upon heating. Thus, \( y \) is Glycine, and \( z \) is Alanine. Therefore, the correct answer is (2) Alanine and Glycine.