6-N,N-Dimethylamino-2,3-naphthalimide: A New Environment-Sensitive Fluorescent Probe in delta- and mu-Selective Opioid Peptides

VAZQUEZ M. V;BLANCO J. B;SALVADORI S;TRAPELLA C;ARGAZZI R;BRYANT S. D;JINSMAA Y;LAZARUS L. H;NEGRI L;GIANNINI E;LATTANZI R;COLUCCI M;BALBONI, GIANFRANCO

2006-01-01

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Abstract

A new environment-sensitive fluorophore, 6-N,N-(dimethylamino)-2,3-naphthalimide (6DMN) was introduced in the delta-selective opioid peptide agonist H-Dmt-Tic-Glu-NH(2) and in the mu-selective opioid peptide agonist endomorphin-2 (H-Tyr-Pro-Phe-Phe-NH(2)). 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 delta-selective irreversible antagonists (H-Dmt-Tic-Glu-NH-(CH(2))(5)-CO-Dap(6DMN)-NH(2) (1) and H-Dmt-Tic-Glu-Dap(6DMN)-NH(2) (2)) were identified as potential fluorescent probes showing good properties for use in studies of distribution and internalization of delta receptors by confocal laser scanning microscopy.