beta-Endorphin: synthesis and properties of human beta-endorphin-(1--28) and its analogs

Three analogs of human beta-endorphin (beta h-EP) were synthesized by the solid-phage method: beta h-EP-(1--28) (I). [Gln8]-beta h-EP-(1--28) (II), and [D-Ala2, Gln8]-beta h-EP-(1--28) (III). Radioreceptor binding assay with use of tritiated beta h-EP as primary ligand gave relative potencies as follows: beta h-EP, 100; I, 85; II, 380; III, 146. Relative potencies in an analgesic assay were: beta h-EP; 100; I, 18; II, 36; III, 13.