Chapter 25, Problem 72PP

Interpretation Introduction

Interpretation:

N-terminal residue of a peptide need to be identified from the given PTH derivative.

Concept introduction:

Edman degradation is a chemical reaction where the N-terminus amino acid is removed when the peptide is treated with phenyl isothiocyanate followed by treatment with trifluoroacetic acid to form phenylthiohydantoin(PTH) derivative and peptide with one amino acid residue less than the starting peptide.  This method can be used to identify the sequence of the amino acid in peptide as only one amino acid is removed each time forming the PTH derivative.  The general scheme for Edman degradation can be shown as,