Table 1. Photophysical properties of model compounds 7a–c and Mag-mito sensor a .
| Absorption λmax (nm), ε × 103 (M–1 cm–1) |
Excitation λmax (nm) |
Emission λmax (nm), Φ
b
|
R max/Rmin | K d,Mg2+ (mM) | K d,Ca2+ (μM) | ||||
| Unbound | Mg2+-saturated | Unbound | Mg2+-saturated | Unbound | Mg2+-saturated | ||||
| 7a | 354, 18.7(1) | 328, 17.9(7) | 354 | 328 | 493, 0.42(1) | 483, 0.235(8) | 2.7 | 8.8(4) | 64(3) |
| 7b | 356, 20.7(7) | 323, 17.4(2) | 356 | 323 | 495, 0.0053(3) | 474, 0.080(4) | N.D. | 7.8(2) | 58.9(8) |
| 7c | 356, 21.2(6) | 330, 16(1) | 356 | 330 | 495, 0.42(1) | 482, 0.25(2) | 2.5 | 9.5(4) | 71(4) |
| Mag-mito | 356, N.D. | 330, N.D. | 356 | 330 | 495, N.D. | 482, N.D. | 2.7 | 6.7(3) | 53.5(9) |
aMeasurements performed in 50 mM PIPES, 100 mM KCl, pH 7.0 at 25 °C. Molar absorptivity coefficients, fluorescence quantum yields and dissociation constants are averages of three determinations; numbers in parenthesis represent the uncertainty on the last significant figure. N.D. = not determined.