FLUORESCENT CHEMOSENSORS FOR DIVALENT ZINC BASED ON ZINC-FINGER DOMAINS - ENHANCED OXIDATIVE STABILITY, METAL-BINDING AFFINITY, AND STRUCTURAL AND FUNCTIONAL-CHARACTERIZATION

The design, synthesis, and characterization of a family of peptides mo deled after the zinc finger domains, which has led to the production o f a fluorescent peptidyl sensor for divalent zinc with enhanced oxidat ive stability, are reported. The chemosensor design comprises a synthe tic peptidyl template and a covalently attached fluorescent reporter w hich is sensitive to metal-induced conformational changes in the polyp eptide construct. The modular synthetic approach employed for the cons truction of these chemosensors allows independent modification of the metal coordination sphere and the fluorescent reporter group. The stru ctural, fluorescence, and zinc binding properties of these peptides an d the effects of integrating various environment sensitive fluorophore s, 4-(dimethylamino)-benzamide, 5-(dimethylamino)naphthalenesulfonamid e, and 3-carboxamidocoumarin, are described. Manipulation of the Ligan d sphere, by removal of one of the pair of thiolate ligands, was under taken to enhance the oxidative stability of the chemosensor. For each of these peptides, the apparent dissociation constant of the peptide-z inc complex has been determined by spectroscopic methods. High-affinit y binding, with dissociation constants ranging from 7 pM to 65 nM, is observed.