Table 1.
Comparison of spectral and photochemical properties of the purified PSmOrange2, PSmOrange and mOrange proteins.
| Protein | mOrange | PSmOrange | PSmOrange2 | |||
|---|---|---|---|---|---|---|
| Orange form | Far-red form | Orange form | Far-red form | Orange form | Far-red form | |
| Absorbance (nm) | 546 | 631 | 548 | 634 | 546 | 619 |
| Emission (nm) | 562 | 662 | 565 | 662 | 561 | 651 |
| Extinction coefficient (M−1 cm−1) | 71,000 | 17,200 | 113,300 | 32,700 | 51,000 | 18,900 |
| Quantum yield | 0.69 | 0.19 | 0.51 | 0.28 | 0.61 | 0.38 |
| Brightness relative to common EGFP (%) | 148 | 10 | 176 | 28 | 95 | 23 |
| pKa | 6.5 a | ND | 6.2 ± 0.1 | 5.6 ± 0.1 | 6.6 ± 0.1 | 5.4 ± 0.1 |
| Photoswitching half- time, t0.5 (s) b | 12 ± 6 | 13.5 ± 1.5 | 4.2 ± 1.1 | |||
| Photoswitching contrast (fold) c | 2,800 ± 200 | 10,700 ± 500 | 96,000 ± 3,800 | |||
| Maturation half-time at 37°C (h) | 2.5 | 1.6 | 3.5 | |||
| Photobleaching t0.5(s) d | (0.65 ± 0.39) | (17 ± 4) | 103 ± 10 (15 ± 5) | 1302 ± 120 (49 ± 8) | 86 ± 2 (12± 4) | 667 ± 25 (20± 1) |
a
Data from 22.
b
Determined at 1,050 W cm−2 at the sample.
c
Determined as the product of the far-red fluorescence increase and the orange fluorescence decrease after photoswitching.
d
Determined at 133 (or 1,130 for the data in brackets) W cm−2 for the orange form and 103 (or 870 for the data in brackets) W cm−2 for the far-red form at a sample. The raw data were normalized to the spectral output of the lamp, transmission profile of the filter and dichroic mirror, absorbance spectra and quantum yields of the proteins, as described 45. ND, not determined. Errors, SD.