Table I.

Fluorescence Characteristics of the Original EGFP and Its Mutant Variants

	Timea	Tryptophanb			Green chromophorec
		λmax (nm)	Parameter Ad	〈τ〉e (ns)	λmax (nm)	Imax	〈τ〉f (ns)
EGFP	1,2	336	1.49	4.0 ± 0.2	512	1	2.6 ± 0.3
EGFP/Arg96Cys	1,2	340	1.18	4.2 ± 0.2	512	0.2	2.5 ± 0.3
EGFP/Arg96Ser	1	324	2.07		––	––	––
	2	323	2.08	2.7 ± 0.3	500	0.02	1.8 ± 0.4
EGFP/Arg96Ala	1	323	2.34		––	––	––
	2	320	2.52	2.2 ± 0.3	502	0.02	2.8 ± 0.4

^aIn column “time” 1 indicates that experiment was performed just after purification, 2 indicates that experiment was performed after samples incubation for one year.

^bTryptophan fluorescence was excited at 297 nm.

^cGreen chromophore fluorescence was excited at 365 nm.

^dA = (I₃₂₀/I₃₆₅)₂₉₇, where I₃₂₀ and I₃₆₅ are fluorescence intensities at λ_em 320 and 365 nm, respectively, and λ_ex 297 nm.

^eThe lifetime of tryptophan fluorescence decay was determined upon fluorescence recording at 340 nm.

^fThe lifetime of green chromophore fluorescence decay was determined upon recording fluorescence at wavelength corresponding to maximum of emission spectrum.