Table 1.

Properties of the orange and far-red forms of the PSmOrange purified protein.

Protein	mOrange		mOrange2		PSmOrange
	Orange form	Far-red form	Orange form	Far-red form	Orange form	Far-red form
Absorbance/Excitation (nm)	546	631	549	632	548	634/636
Emission (nm)	562	662	565	663	565	662
Extinction coefficient (M−1 cm−1)	71,000	17,200	58,000e	ND	113,300	32,700
Quantum yield	0.69e	0.19	0.6e	ND	0.51	0.28
Brightness relative to EGFP (%)	148	10	105	ND	176	28
Photoswitching t0.5 (s) a	12 ± 6		8.0 ± 0.4		15 ± 3
Far-red increase (fold)	190		240		560
Photoswitching contrast (fold) b	2,800 ± 200		ND		10,700 ± 500
Photobleaching t0.5 (s) c	0.65 ± 0.39	17.0 ± 3.7	7 ± 3	ND	15 ± 5	48.5 ± 8.2
pKa d	6.5e	ND	6.5e	ND	6.2 ± 0.1	5.6 ± 0.1
Maturation half-time at 37°C (h)	2.5		4.5e		1.6

^aDetermined at 1,050 W cm⁻² at the sample. Error, s.d. (n = 10).

^bDetermined as the product of the far-red fluorescence increase and the orange fluorescence decrease after photoswitching. Error, s.d. (n = 3).

^cDetermined at 1,130 W cm⁻² at the sample for the orange form and at 870 W cm⁻² at the sample for the far-red form. Error, s.d. (n = 5).

^dError, s.d. (n = 4).

^eRef. ²². ND, not determined.