title: Esterase-activated two-fluorophore system for ratiometric sensing of biological zinc(II).
abstract: Intracellular ester hydrolysis by cytosolic esterases is a common strategy used to trap fluorescent sensors within the cell. We have prepared analogues of Zinpyr-1 (ZP1), an intensity-based fluorescent sensor for Zn2+, that are linked via an amido-ester or diester moiety to a calibrating fluorophore, coumarin 343. These compounds, designated Coumazin-1 and -2, are nonpolar and are quenched by intramolecular interactions between the two fluorophores. Esterase-catalyzed hydrolysis generates a Zn2+-sensitive ZP1-like fluorophore and a Zn2+-insensitive coumarin as a calibrating fluorophore. Upon excitation of the fluorophores, coumarin 343 emission relays information concerning sensor concentration whereas ZP1 emission indicates the relative concentration of Zn2+-bound sensor. This approach enables intracellular monitoring of total sensor concentration and provides a ratiometric system for sensing biological zinc ion.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Carolyn C
authors.initials: CC
authors.lastname: Woodroofe
authors.forename: Annie C
authors.initials: AC
authors.lastname: Won
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Lippard
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D003374:Coumarins / Q000138:chemical synthesis* / Q000737:chemistry; D004950:Esterases / Q000378:metabolism*; D005452:Fluoresceins / Q000138:chemical synthesis* / Q000737:chemistry; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D015394:Molecular Structure; D013050:Spectrometry, Fluorescence; D013552:Swine; D013816:Thermodynamics; D015032:Zinc / Q000032:analysis* / Q000737:chemistry
chemical_list: D003374:Coumarins; D005452:Fluoresceins; D005456:Fluorescent Dyes; C478760:coumazin 1; C030123:coumarin; D004950:Esterases; D015032:Zinc