ABSTRACT
Diode-array UV detection has been adapted for analysis of opioid peptides and their metabolic fragments differing in aromatic amino acid content. In combination with high-performance liquid chromatography, the technique allowed a direct and rapid discrimination between peptides containing phenylalanine, tryptophan and tyrosine, or a combination of these residues. Enkephalin fragments with either tyrosine or phenylalanine, or both, were identified after digestion of the pentapeptide with proteolytic activity recovered from human cerebrospinal fluid. The N-terminal tyrosine-containing fragment of dynorphin A was identified after hydrolysis of the peptide by a cerebrospinal fluid endopeptidase. The study was extended to the analysis of some non-opioid peptides. The Tyr1 analogue of delta-sleep-inducing peptide was easily distinguished from the authentic compound with a tryptophan at the N-terminus. Results indicated that the technique was useful for discriminating between dipeptides differing in aromatic residues that were unresolved by high-performance liquid chromatography.
