title: "Molecular beacon"-based fluorescent assay for selective detection of glutathione and cysteine.
abstract: We report on the development of a fluorescence turn-on "molecular beacon" probe for the detection of glutathione (GSH) and cysteine (Cys). The method is based on a competitive ligation of Hg(2+) ions by GSH/Cys and thymine-thymine (T-T) mismatches in a DNA strand of the self-hybridizing beacon strand. The assay relies on the distance-dependent optical properties of the fluorophore/quencher pair attached to the ends of the molecular beacon DNA strand. In a very selective coordination of Hg(2+) to GSH/Cys, the fluorophore/quencher distance increases concomitantly with the dehybridization and dissociation of the beacon stem T-Hg(2+)-T due to the extraction of Hg(2+) ions. This process results in switching the molecular beacon to the "on" state. The concentration range of the probe is 4-200 nM with the limit of detection (LOD) of 4.1 nM for GSH and 4.2 nM Cys. The probe tested satisfactorily against interference for a range of amino acids including sulfur-containing methionine.
authors.affiliation: Department of Chemistry, State University of New York at Potsdam, Potsdam, New York 13676, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Xu
authors.forename: Maria
authors.initials: M
authors.lastname: Hepel
mesh_terms: D003545:Cysteine / Q000032:analysis* / Q000737:chemistry; D004247:DNA / Q000737:chemistry; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D005978:Glutathione / Q000032:analysis* / Q000737:chemistry; D008628:Mercury / Q000737:chemistry; D009690:Nucleic Acid Conformation
chemical_list: D004247:DNA; D008628:Mercury; D005978:Glutathione; D003545:Cysteine