The dipeptide `(III)` is:

Options

A. Val `rarr` Leu
B. Leu `rarr` Val
C. Gly `rarr` Ala
D. Ala `rarr` Gly

Answer

A

Explanation

(1) `DNP` method or Leucine aminopeptidase enzyme releasess `N-`terminal amino acid.
`underset((I))"Tetrapeptide"rarrunderset(("N-terminal"))("Alanine")+"Tripeptide"`
`underset(("N-terminal"))(Ala)rarr"Tripeptide"`
(2) Hydrazinolysis or carboxypeptidase enzyme releases `C-`terminal amino acid.
`underset((II))("Tripetide")rarr"Dipeptide"+underset(("C-terminal"))("Glycine")`
`underset(("N-terminal"))(Ala)rarr"Dipeptide"rarrunderset(("C-terminal"))(Gly)`
(3) Dipeptide `(III)` now contains only two amino acids, valine and Leucine. Edman method releases `N-`terminal amino acid.