"DAKLI": a multipurpose ligand with high affinity and selectivity for dynorphin (kappa opioid) binding sites.

Abstract
We describe a synthetic ligand, "DAKLI" (Dynorphin A-analogue Kappa LIgand), related to the opioid peptide dynorphin A A. A single reactive amino group at the extended carobxyl teminus permits various reporter groups to be attached, such as 125I-labeled Bolton-Hunter reagent, fluorescein isothiocyonate, or biotin. These derivatives have high affinity and selectivity for the dynorphin (.KAPPA. opioid) receptor. An incidental finding is that untreated guinea pig brain membranes have saturable avidin binding sites.