Table 4. Spectroscopic properties of Katushka, eqFP650 and eqFP670 mutants.

Φ_F, quantum yield. E _mol, extinction coefficient. B, brightness (E _mol × Φ_F). , brightness relative to EGFP [product of Φ_F and E _mol compared to the brightness of EGFP (53 000 M ⁻¹ cm⁻¹ × 0.60) (Patterson et al., 1997 ▶)]. , brightness relative to parental protein. /, excitation and emission maxima.

Mutant	ΦF	E mol	B	(%)	(%)	(nm)	(nm)
EGFP†	0.60	53000	31800	100		489	509
					(%)
Katushka	0.34	65000	22100	69	100	588	635
Katushka/S143N	0.02	33500	500	2	2	565	604
Katushka/S158N	0.29	75500	21600	68	98	588	635
Katushka/S143N/S158N	0.10	60500	5900	19	27	605	652
					(%)
eqFP670	0.06	70000	3900	12	100	605	670
eqFP670/N143S‡	0.17	77000	13500	42	346	580	650
eqFP670/N158S	0.02	46500	1000	3	24	570	620
eqFP670/N143S/N158S‡	0.24	48000	11800	37	301	588	647
eqFP670/T11M	0.06	56500	3200	10	82	605	670
					(%)
eqFP650	0.24	65000	15600	49	100	592	650
eqFP650/M11T‡	0.24	69000	16600	52	107	588	648

^†The values for EGFP are given for comparison.

^‡For mutants eqFP670/N143S, eqFP670/N143S/N158S and eqFP650/M11T the extinction coefficient was corrected for an additional peak at 380 nm (E _mol = 70000) upon NaOH denaturation.