Fluorescent sensors for Zn(2+) based on a fluorescein platform: synthesis, properties and intracellular distribution.
Two new fluorescent sensors for Zn(2+) that utilize fluorescein as a reporting group, Zinpyr-1 and Zinpyr-2, have been synthesized and characterized. Zinpyr-1 is prepared in one step via a Mannich reaction, and Zinpyr-2 is obtained in a multistep synthesis that utilizes 4',5'-fluorescein dicarboxaldehyde as a key intermediate. Both Zinpyr sensors have excitation and emission wavelengths in the visible range ( approximately 500 nm), dissociation constants (K(d1)) for Zn(2+) of <1 nM, quantum yields approaching unity (Phi = approximately 0.9), and cell permeability, making them well-suited for intracellular applications. A 3- to 5-fold fluorescent enhancement is observed under simulated physiological conditions corresponding to the binding of the Zn(2+) cation to the sensor, which inhibits a photoinduced electron transfer (PET) quenching pathway. The X-ray crystal structure of a 2:1 Zn(2+):Zinpyr-1 complex has also been solved, and is the first structurally characterized example of a complex of fluorescein substituted with metal binding ligands.
Burdette
S C
SC
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA.
Walkup
G K
GK
Spingler
B
B
Tsien
R Y
RY
Lippard
S J
SJ
D000818:Animals; D019556:COS Cells / Q000737:chemistry; D002413:Cations, Divalent; D018360:Crystallography, X-Ray; D005452:Fluoresceins / Q000138:chemical synthesis* / Q000737:chemistry; D005456:Fluorescent Dyes; D013050:Spectrometry, Fluorescence; D015032:Zinc / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology
D002413:Cations, Divalent; D005452:Fluoresceins; D005456:Fluorescent Dyes; D015032:Zinc