Biomolecules and Chemistry in Everyday Life - Result Question 30
31. A tetrapeptide has $- COOH$ group on alanine. This produces glycine (Gly), valine (Val), phenyl alanine (Phe) and alanine (Ala), on complete hydrolysis. For this tetrapeptide, the number of possible sequences (primary structures) with $-NH _2$ group attached to a chiral centre is
(2013 Adv.)
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Answer:
Correct Answer: 31. $(4)$
Solution:
- PLAN: A peptide linkage is hydrolysed to two free amino acids.
$C^{*}$ is chiral carbon tetrapeptide has four amino acids joined by three peptide linkage.
$-COOH$ group is on alanine part, thus it is at fixed $C-$ terminal position in each combination.
Glycine is optically inactive thus it cannot be on the $N-$ terminal side. Thus, possible combinations are
Phe-Gly-Val-Ala,
Phe-Val-Gly-Ala,
Val-Gly-Phe-Ala,
Val-Phe-Gly-Ala
Thus, in all four combinations are possible.
BETA
