Table 1.
Fluorescent Protein | Excitation/Emission maxima (nm) | Extinction coefficient (M-1 cm-1) | Quantum yield | Relative brightnessa | Maturation half-time (h) | Photobleaching half- time (s)b | pKa |
DsRed-Express2c | 554/591 | 35,600 | 0.42 | 0.41 | 0.7 | 64 ± 4 | 4.5 |
E2-Red/Green (green) | 484/498 | 100,200 | 0.06 | 0.17 | 0.4 | 236 ± 8d | 4.0 |
E2-Red/Green (red) | 560/585 | 53,800 | 0.67 | 0.98 | 1.2 | 93 ± 3 | 4.5 |
E2-Orange | 540/561 | 36,500 | 0.54 | 0.54 | 1.3 | 81 ± 3 | 4.5 |
mOrange2 | 549/563 | 56,300 | 0.49 | 0.75 | 4.5 | 40 ± 3 | 7.5 |
KO | 548/560 | 72,800 | 0.55 | 1.1 | 3.8 | 21 ± 2 | 5.0 |
mKO2c | 549/563 | 54,300 | 0.41 | 0.54 | 1.2 | 9 ± 1 | 5.0 |
Unless otherwise indicated, all measurements were carried out during the present study using standardized procedures.
a Brightness was calculated as the product of extinction coefficient and quantum yield, and was normalized to a value of 1 for wild-type DsRed as calculated from Ref. 5.
b Photobleaching half-times during widefield illumination are listed as mean ± s.e.m. for three independent replicates.
c For DsRed-Express2 and mKO2, all data except the pKa measurements were taken from Ref. 5.
d The photobleaching half-time for the green chromophore of E2-Red/Green cannot be compared directly to the photobleaching half-times of red chromophores because a different filter set was used.