Propose two structures for a tripeptide that contains

Step 1 of 2

In this exercise, we’re asked to propose two di?erent structures for a tripeptide that contains glycine, L-alanine, and L-phenylalanine but yet does not react with phenyl isothiocyanate.

Recall that phenyl isothiocyanate is a chemical reagent used during the Edman Degradation reaction; normally the intent is to cleave off one peptide from the N-terminus of a polypeptide, so that the amino acids in the polypeptide can be sequentially identified. However, the nucleophilic carbon in the isothiocyanate group requires a free amino group in order for the nucleophilic attack to occur.