Chapter 24, Problem 7PP

Interpretation Introduction

Interpretation:

The reactions involved in a sequential Edman degradation of MIR are to be written.

Concept introduction:

舧 Amino acids are organic compounds containing amine ($-{\text{NH}}_2$) and carboxyl ($-\text{COOH}$) functional group along with a side chain (R group) specific to each amino acid.

舧 Edman degradation method is used for identification of the N-terminal amino acid in a peptideup to a maximum length of about 60 residues. In this method, phenylisothiocynate reacts with the amino group of the terminal position to form a cyclic phenylthiocarbamoyl derivative.  Under acidic conditions, the terminal amino acid is cleaved from the main chain as thizolinone derivative.  Thizolinone derivative is extracted to the organic solvent and it forms phenylthiohydantoin-amino acid (PTH-amino acid) derivative in the presence of acid.  PTH-amino acid complex can be identified by comparison with the standard amino acids. These steps can be repeated again with the next amino acid residue in the peptide chain.