Which from following amino acids contains 'S' in its side chain (R)?

Question

A dipeptide, “x”, on complete hydrolysis gives “y” and “z”; “y” on treatment with aqueous HNO$_2$, produces lactic acid. On the other hand, “z” on heating gives the following cyclic molecule.

Based on the information given, the dipeptide X is:

Answer 1

Step 1: Understanding the Question:
The question asks to identify the amino acid that contains a sulfur ('S') atom in its varying side chain, also known as the R-group.
Step 2: Detailed Explanation:
Let us examine the side chains of the given options:
(A) Methionine: The side chain is $ -\text{CH}_2-\text{CH}_2-\text{S}-\text{CH}_3 $. It contains a sulfur atom (thioether group).
(B) Lysine: The side chain is $ -\text{CH}_2-\text{CH}_2-\text{CH}_2-\text{CH}_2-\text{NH}_2 $. It contains an amino group but no sulfur.
(C) Glutamic acid: The side chain is $ -\text{CH}_2-\text{CH}_2-\text{COOH} $. It contains a carboxyl group but no sulfur.
(D) Glycine: The side chain is just an $ -\text{H} $ atom. It is the simplest amino acid and contains no sulfur.
Step 3: Final Answer:
Methionine is the only amino acid among the choices that contains a sulfur atom in its side chain.

Which from following amino acids contains 'S' in its side chain (R)?

Show Hint

The Correct Option is A

Solution and Explanation

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