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Table 1 Properties of FPs.

From: Noncytotoxic orange and red/green derivatives of DsRed-Express2 for whole-cell labeling

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
  1. Unless otherwise indicated, all measurements were carried out during the present study using standardized procedures.
  2. 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.
  3. b Photobleaching half-times during widefield illumination are listed as mean ± s.e.m. for three independent replicates.
  4. c For DsRed-Express2 and mKO2, all data except the pKa measurements were taken from Ref. 5.
  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.