Analysis of Amino Acid Phenylthiohydantoins by Gas Chromatography and High Performance Liquid Chromatography

Abstract

Amino acid phenylthiohydantoins (PTHs) are formed in Edman’s now classic technique for determining the primary structure of peptides and proteins. Introduced over 20 years ago, it is still the most effective and widely used method for sequence analysis. While X-ray crystallographic and mass spectrometric approaches remain attractive because they do not involve tedious step-wise analyses, their utility is restricted by requirements inherent in the methods. Thus, for the X-ray technique, suitable crystals and adequate stability during X-ray bombardment are unattainable for many proteins and peptides. Even with good crystals, unambiguous distinction of all amino acids is often impossible with obtainable data. Limited volatility is the main deterrent to the wider use of mass spectrometry in peptide analysis. Greater use of the method will follow improvements in chemical techniques for converting peptides to suitable derivatives, but it is unlikely that it will ever be possible to analyze peptides containing more than about 15 residues.