β‐ENDORPHIN: SYNTHESIS AND RADIORECEPTOR BINDING ACTIVITY OF βh‐ENDORPHIN‐(1–27) AND ITS ANALOGS

Abstract
.beta.h-Endorphin-(1-27) I [Ac-Tyr1]-.beta.h-endorphin-(1-27) II, [Gln8]-.beta.n-endorphin-(1-27) III, and [Ac-Tyr1, Gln8]-.beta.h-endorphin-(1-27) IV were synthesized by the solid-phase method. The binding potency of I-IV to rat brain membrane preparations was measured by radioreceptor binding assay. The relative potencies were .beta.h-endorphin, 100; I, 30; II, 0.04; III, 90; IV, 0.07.