Question

The correct structure of dipeptide, Gly-Ala (glycyl alanine) is:

• A. \(\text{H}_2\text{NCH}_2\text{CONHCH(CH}_3\text{)COOH}\)
• B. \(\text{HOOC} - \text{CH}_2 - \text{NH} - \text{CO} - \text{CH(CH}_3\text{)} - \text{NH}_2\)
• C. \(\text{HOOC} - \text{CH(CH}_3\text{)} - \text{NH} - \text{CO} - \text{CH}_2 - \text{NH}_2\)
• D. \(\text{H}_2\text{N} - \text{CH(CH}_3\text{)} - \text{CO} - \text{NH} - \text{CH}_2 - \text{COOH}\)

Answer 1

The Correct Option is A

The formation of a dipeptide, exemplified by Gly-Ala (glycyl alanine), entails the creation of a peptide bond between two amino acids. In this instance, glycine (\(\text{NH}_2\text{CH}_2\text{COOH}\)) serves as the first amino acid, and alanine (\(\text{NH}_2\text{CH(CH}_3\text{)COOH}\)) as the second. Dipeptide formation involves the reaction between the carboxyl group \(-\text{COOH}\) of the initial amino acid and the amino group \(-\text{NH}_2\) of the subsequent one, releasing a water molecule and generating a peptide bond \(\text{-CONH-}\).

Construction of Gly-Ala proceeds as follows:

1. Determine the N-terminus of the dipeptide: The N-terminus of Gly-Ala originates from glycine, represented as \(\text{NH}_2\text{CH}_2\text{-}\).
2. Form the peptide bond: A peptide bond (\(\text{-CONH-}\)) is established by linking glycine's carboxyl group with alanine's amino group.
3. Append the alanine structure: The moiety \(\text{CH(CH}_3\text{)COOH}\), derived from alanine, is attached after the peptide bond to complete the dipeptide.

The resultant structure for the dipeptide Gly-Ala is: \(\text{H}_2\text{NCH}_2\text{CONHCH(CH}_3\text{)COOH}\)

This structure accurately depicts glycyl alanine, featuring an amino group from glycine at the N-terminus and a carboxylic acid group from alanine at the C-terminus.