Edman Degradation

Abstract

The reaction between phenyl isothiocyanate and the free amino group of the N ‐terminal amino acid within a polypeptide to generate a thiourea, which upon the intramolecular cyclization via the nucleophilic addition of the amino group to adjacent amide carbonyl cleaves the N ‐terminal amino acids as a phenylthiohydantoin derivative and leaves the second amino acid as the N ‐terminus again, is generally known as the Edman degradation. This method shows a few disadvantages and, to overcome these weaknesses, the reaction has been carried out by means of solid‐phase support synthesis (SPSS). Further development has made this degradation valuable for sequencing the C‐terminal segments of hydroxyethylamine‐derived peptides and a useful method for the synthesis of 2‐iminohydantoins.