Table 3.

Chromophore geometry in the GFPs, angles in degrees. See reference (27) for a definition of twist and tilt angles. The quantum yields were measured by excitation at maximum of absorbance band at specific pH

Model	QY	Twist	Tilt
wt-GFP	0.79	0.0	3.7
DsRed	0.79	0.9	0.2
S65T/H148D (pH 5.6)	0.21	9.5	9.6
S65T/H148D (pH 10.0)	0.32	3.2	9.0
S65T/H148N (pH 5.0)	0.01	7.6	13.5
S65T/H148N (pH 9.5)	0.45	1.3	7.7
H148D (pH 9.0)	0.15	0.4	12.8