Question

Complete hydrolysis of a nonapeptide gave 3 ala, 2 phe, 2 asp, gly, and ser. Reaction of the nonapeptide with Sanger's reagent (1-fluoro-2,4-dinitrobenzene) followed by hydrolysis gave N-(2,4-dinitrophenyl) alanine. Partial hydrolysis of the nonapeptide gave the following fragments: gly-ala-phe ala-asp-gly-ala phe-ser-ala ser-ala-phe-asp. Which one of the following is the nonapeptide's pripary structure? A) ala-asp-gly-ala-asp-ala-phe-sor-phe B) ala-asp-gly-ala-phe-ser-ala-phe-b C) ala-phe-asp-gly-ala-asp-ser-phe-ala D) gly-ala-phe-ser-ala-phe-asp-asp-ala

Answer 1

Answer:

Alanine is obtained as the first amino acid, taking into account that the reaction with the Sanger reagent hydrolyzes N- (2,4-dinitrophenyl) alanine. thus with the fragments of the partial hydrolysis they are organized to create a polypetidic chain

ala-asp-gly-ala

gly-ala-phe

phe-be-wing

be-wing-phe-asp

We obtain that the correct sequence of the peptide is "ala-asp-gly-ala-phe-ser-ala-phe-asp"