Design and Synthesis of Highly Specific and Selective Enkephalin Analog Containing S-Npys-Cysteine for &δ Opioid Receptors

Article abstract of DOI:10.1246/cl.1992.1259

Enkephalin analogs containing S-(3-nitro-2-pyridinesulfenyl)cysteine at positions of 1, 5, or 6 were synthesized for searching possible thiol groups in the opioid receptors.In the radio-ligand receptor assay and biological assays, 2, Leu⁵>enkephalyl-Cys(Npys)⁶ exhibited a very high affinity and selectivity for δ over μ receptors, and its covalent attachment to δ receptors through the disulfide bonding was evidenced.