title: Near-membrane iminocoumarin-based low affinity fluorescent Ca(2+) indicators.
abstract: Two new potential near-membrane iminocoumarin-based fluorescent Ca(2+) indicators were synthesized and the spectral profiles of their free and Ca(2+) bound forms were studied. The probes incorporate in their BAPTA-related structures, the 3-(benzimidazolyl)iminocoumarin or the 3-(benzothiazolyl)iminocoumarin moiety, substituted at the imino nitrogen with an n-dodecyl lipophilic chain. The compounds are excited with visible light and have Ca(2+) dissociation constant values of 5.50 and 4.49 microM, respectively, the highest reported to date in the literature. Fluorescence spectra studies indicated a clear shift in their excitation wavelength maxima upon Ca(2+) binding along with changes in fluorescence intensity that enable the compounds to be used as ratiometric near-membrane, low Ca(2+) affinity probes.
authors.affiliation: Department of Chemistry, University of Crete, Heraklion, 71 409 Crete, Greece.
authors.forename: F
authors.initials: F
authors.lastname: Liepouri
authors.forename: T G
authors.initials: TG
authors.lastname: Deligeorgiev
authors.forename: Z
authors.initials: Z
authors.lastname: Veneti
authors.forename: C
authors.initials: C
authors.lastname: Savakis
authors.forename: H E
authors.initials: HE
authors.lastname: Katerinopoulos
mesh_terms: D000818:Animals; D001562:Benzimidazoles / Q000138:chemical synthesis*; D001578:Benzopyrans / Q000138:chemical synthesis*; D001665:Binding Sites / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000032:analysis*; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects*; D003374:Coumarins / Q000737:chemistry*; D004331:Drosophila melanogaster; D004625:Embryo, Nonmammalian; D005456:Fluorescent Dyes / Q000138:chemical synthesis*; D007202:Indicators and Reagents / Q000138:chemical synthesis*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008563:Membrane Lipids / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D013057:Spectrum Analysis; D013844:Thiazoles / Q000138:chemical synthesis*
chemical_list: D001562:Benzimidazoles; D001578:Benzopyrans; C470317:C12-BIIC compound; C470318:C12-BTIC compound; D003374:Coumarins; D005456:Fluorescent Dyes; D007202:Indicators and Reagents; D008563:Membrane Lipids; D013844:Thiazoles; C030123:coumarin; D002118:Calcium