Table 1.
Probe | Ca2+ | ε (mM−1 cm−1) (λABS*) | pKa† | λEx* | pH 7.2 | pH 8.0 | ||||
---|---|---|---|---|---|---|---|---|---|---|
Kd for Ca2+ (μM) | Dynamic range‡ | Hill coefficient | Kd for Ca2+ (μM) | Dynamic range‡ | Hill coefficient | |||||
R-GECO1mt | − | 27 (445), 7 (576) | 8.9 | 565 | 0.19 ± 0.02§ | 22.2 ± 0.5§ | 2.20 ± 0.10§ | 0.14 ± 0.01§ | 8.8 ± 0.1§ | 2.12 ± 0.10§ |
+ | 54 (562) | 6.2 | ||||||||
R-CEPIA3mt | − | 26 (445), 6 (576) | 8.9 | 565 | 3.7 ± 0.5 | 30.0 ± 1.5 | 0.96 ± 0.02 | 3.3 ± 0.2 | 8.9 ± 0.1 | 0.93 ± 0.01 |
+ | 49 (562) | 6.5 | ||||||||
R-CEPIA4mt | − | 25 (445), 6 (576) | 8.8 | 565 | 26.9 ± 1.0 | 23.9 ± 0.4 | 1.51 ± 0.01 | 21.4 ± 0.3 | 4.7 ± 0.1 | 1.86 ± 0.02 |
+ | 17 (450), 30 (562) | 6.5 |
*λABS and λEx are the maximum wavelength of absorption and fluorescence excitation spectra, respectively.
†pKa is determined as the pH at half-maximal fluorescence intensity calculated by fitting Hill equation to each plot.
‡Dynamic range indicates the ratio of the maximum to minimum fluorescence intensity (Fmax/Fmin).
§Mean ± s.e.m.