6-N,N-Dimethylamino-2,3-naphthalimide: A New Environment-Sensitive Fluorescent Probe in δ- and μ-Selective Opioid Peptides
journal contributionposted on 15.06.2006, 00:00 by M. Eugenio Vázquez, Juan B. Blanco, Severo Salvadori, Claudio Trapella, Roberto Argazzi, Sharon D. Bryant, Yunden Jinsmaa, Lawrence H. Lazarus, Lucia Negri, Elisa Giannini, Roberta Lattanzi, Mariantonella Colucci, Gianfranco Balboni
A new environment-sensitive fluorophore, 6-N,N-(dimethylamino)-2,3-naphthalimide (6DMN) was introduced in the δ-selective opioid peptide agonist H-Dmt-Tic-Glu-NH2 and in the μ-selective opioid peptide agonist endomorphin-2 (H-Tyr-Pro-Phe-Phe-NH2). Environment-sensitive fluorophores are a special class of chromophores that generally exhibit a low quantum yield in aqueous solution but become highly fluorescent in nonpolar solvents or when bound to hydrophobic sites in proteins or membranes. New fluorescent δ-selective irreversible antagonists (H-Dmt-Tic-Glu-NH-(CH2)5-CO-Dap(6DMN)-NH2 (1) and H-Dmt-Tic-Glu-Dap(6DMN)-NH2 (2)) were identified as potential fluorescent probes showing good properties for use in studies of distribution and internalization of δ receptors by confocal laser scanning microscopy.