Met-enkephalin: Rapid separation from brain extracts using high-pressure liquid chromatography,and quantitation by binding assay

Met-enkephalin can be rapidly separated with high recovery from leu-enkephalin, -endorphin, and enkephalin metabolites by high-pressure liquid chromatography on a Dupont SCX column. The technique permits separation of endogenous enkephalins from brain extracts for measurement by opiate-receptor binding assay, immunoassay, or for study of the incorporation of radiolabeled amino acids into enkephalin. Using this technique, met-enkephalin was separated from striatal extracts of rats killed by focused microwave irradiation and quantitated by the opiate-receptor binding assay. The concentration of met-enkephalin in the column eluate was 1.3 g/g tissue. This value is comparable to that obtained by radioimmunoassay without purification of the extracts.Pharmacology Research Associate, Pharmacology Research Associate Program, National Institute of General Medical Sciences.