fura 2 (potassium salt)

Fura-2 potassium salt is a commonly used UV-excitable fluorescent probe for intracellular calcium ion imaging.

Rhod-2 (potassium salt) is a water-soluble, red fluorescent calcium indicator that exhibits a significant shift in fluorescence intensity upon calcium binding (ex max = 549 nm; calcium-free v. ex em max = 552 581 nm; calcium-bound). Unlike the UV-excitable indicators fura-2 and indo-1, it does not demonstrate a spectral shift.

Fura-FF AM is a cell-permeable acetoxymethyl ester of the fluorescence calcium indicator fura-FF (potassium salt). Upon entering cells, it is hydrolyzed by intracellular esterases to produce fura-FF, a difluorinated derivative of the calcium indicator fura-2. Unlike fura-2, fura-FF has negligible magnesium sensitivity, reducing interference from this cation, and a higher calcium dissociation constant (Kd(calcium) = 6 μM for fura-FF and 0.14 μM for fura-2). The spectral properties of fura-FF are similar to those of fura-2, with fura-FF displaying excitation emission spectra of 365 514 nm in the absence of calcium and shifting to 339 507 nm in the presence of high calcium concentrations. Low affinity calcium dyes, including fura-FF, are preferred for studying compartments with high calcium concentrations, such as mitochondria, or in cell systems with relatively low calcium buffering capacities, such as neuronal dendrites and spines.