[D-Ala2,Phe(p-NO2)4,Leu5]enkephalin amide and N(α)-[D-Ala2,Leu5]enkephalyl-N(ε)-acetyl-lysine amide: Synthesis and biological properties of prospective enkephalin cooperative-affinity and photoaffinity labels

Article abstract of DOI:10.1002/hlca.19790620219

As a study preliminary to attempts at photoaffinity and cooperative affinity labelling of cells and cell membrane vesicles bearing opiate receptors, the title compounds were prepared and tested by rat brain membrane binding assays and by a modified guinea-pig ileum bio-assay. The potency of the two compounds in both systems was considerably greater than that of the standard peptide, [Leu⁵]enkephalin, justifying further work with these and similar compounds.