Fura-2 pentapotassium salt

Fura-2 pentapotassium salt is a widely used UV-excitable fluorescent calcium indicator. It is a fluorophore chelating probe for Ca2+ used widely in biological systems to analyze intracellular calcium levels. It can be used to detect calcium in cells. A diagnostic shift in the excitation spectrum from 363nm to 335nm indicates FURA-2 chelation to Ca2+. Upon calcium binding, the fluorescent excitation maximum of the indicator undergoes a blue shift from 363 nm (Ca2+-free) to 335 nm (Ca2+-saturated), while the fluorescence emission maximum is relatively unchanged at ~510 nm. Analysis of Ca2+ flux in and out of cells with Fura-2 introduces a powerful spectrographic handle to investigate and elucidate correlated biological events such as neuronal ion channel activation. A major use of Fura-2 is in drug discovery, for measuring intracellular calcium mobilization after activation of G protein-coupled receptors (GPCRs) and calcium channels. It can also be used as a zinc indicator or measuring membrane potential. Fura-2 fluorescence can be detected using flow cytometry, fluorescence microscopy, or certain fluoresence microplate readers. Fura-2 potassium salt is a cell-impermeable fluorescent probe for detection Ca2+ in a ratiometric mode. However, it may be loaded into cells via microinjection or scrape loading. Spectral data: λEx 363nm, λEm 512nm in water.