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.