High-performance liquid chromatography and diode-array detection for the identification of peptides containing aromatic amino acids in studies of endorphin-degrading activity in human cerebrospinal fluid.

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.