Fura-FF AM is a cell-permeable acetoxymethyl ester of the fluorescence calcium indicator fura-FF (potassium salt) . As fura-FF AM enters cells, it is hydrolyzed by intracellular esterases to produce fura-FF. Fura-FF is a difluorinated derivative of the calcium indicator fura-2 . Unlike, fura-2, fura-FF has negligible magnesium sensitivity, thus reducing interference from this cation.
1 Fura-FF also has a higher calcium dissociation constant than fura-2 (K
d(calcium) = 6 and 0.14 μM, respectively).
1,2 However, the spectral properties of fura-FF and fura-2 are similar with fura-FF displaying excitation/emission spectra of 365/514 nm in the absence of calcium, with a shift to 339/507 nm in the presence of a high calcium concentration.
3 Low affinity calcium dyes, including fura-FF, are preferred for studying compartments with high concentrations of calcium, such as mitochondria, or in cell systems that have relatively low calcium buffering capacities, such as neuronal dendrites and spines.
4,5,6
1. Hyrc, K.L., Bownik, J.M., and Goldberg, M.P. Ionic selectivity of low-affinity ratiometric calcium indicators: mag-Fura-2, Fura-2FF and BTC Cell Calcium 27(2),75-86(2000).
2. Grynkiewicz, G., Poenie, M., and Tsien, R.Y. A new generation of Ca2+ indicators with greatly improved fluorescence properties J. Biol. Chem. 260(6),3440-3450(1985).
3. Ruggiu, A.A., Bannwarth, M., and Johnsson, K. Fura-2FF-based calcium indicator for protein labeling Org. Biomol. Chem. 8(15),3398-3401(2010).
4. Aponte, Y., Bischofberger, J., and Jonas, P. Efficient Ca2+ buffering in fast-spiking basket cells of rat hippocampus J. Physiol. 586(8),2061-2075(2008).
5. Canepari, M., Vogt, K., and Zecevic, D. Combining voltage and calcium imaging from neuronal dendrites Cell. Mol. Neurobiol. 28(8),1079-1093(2008).
6. Marcu, R., Neely, C.K., Karamanlidis, G., et al. Multi-parameter measurement of the permeability transition pore opening in isolated mouse heart mitochondria J. Vis. Exp. 67:4131,(2012).
