The effect of thiodiglycol and dithiothreitol on the alkaline hydrolysis products of certain amino acid phenylthiohydantoins.

The thiazolinone and phenylthiohydantoin derivatives of most amino acids can be hydrolyzed with alkaline dithionite to generate the free amino acid. The acidification of this hydrolysate with 3 N HCl containing thiodiglycol leads in the case of glutamic acid, glutamine, aspartic acid, asparagine, and S-carboxy-methylcysteine to the generation of ninhydrin-reacting components having the chromatographic properties of other amino acids. The use of dithiothreitol instead of thiodiglycol appears to be more satisfactory in most instances.