Optical resolution of phenylthiohydantoin amino acids by capillary electrophoresis and identification of the phenylthiohydantoin-D-amino acid residue of [D-Ala(2)]-methionine enkephalin

This is an initial report to propose a protein sequence analysis system with DL differentiation using capillary electrophoresis (CE). This system consists of a protein sequencer and a CE system. After fractionation of phenylthiohydantoin (PTH)-amino acids using a protein sequencer, optical resolution for each PTH-amino acid is performed by CE using some chiral selectors such as digitonin, beta-escin and others. As a model peptide, [D-Ala(2)]-methionine enkephalin (L-Tyr-D-Ala-Gly-L-Phe-L-Met), was used and the sequence with DL differentiation was determined, with the exception of the fourth amino acid, L-Phe, using our proposed system.