. Author manuscript; available in PMC: 2009 Nov 1.

Published in final edited form as: Methods. 2008 Oct 16;46(3):143–151. doi: 10.1016/j.ymeth.2008.09.025

Table 1. Equilibrium Affinities and Binding Rate Constants of Ca²⁺ indicator dyes.

The time constant (τ) for Buffer/Calcium equilibrium is defined as: 1/τ = k_on{Buffer_total} assuming a 1mM Buffer concentration and a 1:1 reaction as described in the text. When available, in situ cytoplasmic values are reported with the corresponding in vitro estimates given in parenthesis. Note that the k_on values greater than 10 × 10⁷ M-1s-1 are diffusion limited (31).

Ca ²⁺ dye	K_on, Ca²⁺ (X10⁷ M-1s-1)	K_off, Ca²⁺ (s-1)	τequilibrium (μs)	K_d, Ca²⁺ (μM)	K_d, Mg²⁺ (mM)	Reference
Fura-2	15	23	6.7	0.23, (0.14)	-	(27-29)
Magnesium Green NTA	9	1750	11	19,(6)	2.4, (1.0)	(30, 31)
Furaptra	5.0	5000	20	100, (17)	5.3, (2.5)	(30, 31)
Mag-fura-red	2.1	5000	-	17	2.5	(31)

Table 1. Equilibrium Affinities and Binding Rate Constants of Ca2+ indicator dyes.

Table 1. Equilibrium Affinities and Binding Rate Constants of Ca²⁺ indicator dyes.