Table 1.
Spectral Properties of mCherry and Kriek.
| RFP | λabs(n m) | λex(n m) | λem(n m) | Φfl | εmax M-1 cm-1 | Widefield Photobleaching Time-Constant(s) | Confocal Photobleaching Time-Constant(s) |
|---|---|---|---|---|---|---|---|
| mCherry | 587 | 591 | 608 | 0.23 | 97,000 | 110 | 470 (75 %) 300 (25 %) |
| Kriek | 592 | 593 | 618 | 0.08 | 100,000 | 280 | 1890 (88 %) 45 (12 %) |
Φfl is the fluorescence quantum yield, and εmax is the extinction coefficient at the absorption maximum. The extinction coefficients for mCherry and Kriek have a standard error of the mean of 9,000 and 13,000, respectively, and are statistically insignificant (paired sample t-test, p = 0.22). Widefield photobleaching was performed on immobilized E. coli, and confocal photobleaching was performed on nuclear-localized FPs in adherent HeLa cells. For widefield illumination, the gradual decrease in fluorescence intensity was fit to a monoexponential decay. For confocal illumination a biexponential fit was necessary, and the time-constants and their pre-exponential factor in parentheses are reported. The weighted time-constants of confocal photobleaching are 1700 and 600 seconds, for Kriek and mCherry, respectively.