morphiceptin morphiceptin morphiceptin is a tetrapeptide (tyr-pro-phe-pro-nh2) that is a selective μ-opioid receptor agonist. it is derived from β-casomorphin and has over 1,000 times selectivity for μ- over δ-opioid receptors. when injected intracerebroventricularly (into the ventricular system of the brain), morphiceptin had an analgesic ed50 of 1.7 nmol per animal. the analgesic effects of morphiceptin were reversed by naloxone, meaning that the analgesic effect is mediated by the μ-opioid receptor. morphiceptin names iupac name (2s)-1--n--1-oxo-3-phenylpropan-2-yl]pyrrolidine-2-carboxamide other names tyr-pro-phe-pro-nh2, plo17 identifiers cas number 74135-04-9 y 3d model (jsmol) interactive image chemspider 106565 n pubchem cid 119303 unii 97tza8anpc y comptox dashboard (epa) dtxsid10995574 inchi inchi=1s/c28h35n5o5/c29-21(16-19-10-12-20(34)13-11-19)27(37)33-15-5-9-24(33)26(36)31-22(17-18-6-2-1-3-7-18)28(38)32-14-4-8-23(32)25(30)35/h1-3,6-7,10-13,21-24,34h,4-5,8-9,14-17,29h2,(h2,30,35)(h,31,36)/t21-,22-,23-,24-/m0/s1 nkey: lsqxziureidshz-zjzgaynasa-n ninchi=1/c28h35n5o5/c29-21(16-19-10-12-20(34)13-11-19)27(37)33-15-5-9-24(33)26(36)31-22(17-18-6-2-1-3-7-18)28(38)32-14-4-8-23(32)25(30)35/h1-3,6-7,10-13,21-24,34h,4-5,8-9,14-17,29h2,(h2,30,35)(h,31,36)/t21-,22-,23-,24-/m0/s1key: lsqxziureidshz-zjzgaynabz smiles c1ccc(cc1)c(c(=o)n2ccc2c(=o)n)nc(=o)3cccn3c(=o)(cc4ccc(cc4)o)n properties chemical formula c28h35n5o5 molar mass 521.6 g/mol except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). n verify (what is yn ?) infobox references morphiceptin is the (1s,2s,3s,4s)-form whereas deproceptin is the (1s,2s,3s,4r)-form .