Table 1.

Driving Force Δ$\overline{\nu }$ Predictions for Each Dronpa2 Hybrid^a

chromophore variant	driving force Δ$\overline{\nu }$ (cm−1)	difference from Dronpa2 ΔΔ$\overline{\nu }$ (cm−1)	hybrid protein	point mutant driving force ΔΔ$\overline{\nu }$ (cm−1)	substituent driving force ΔΔ$\overline{\nu }$ (cm−1)	predicted combined driving force Δ$\overline{\nu }$ (cm−1)
Dronpa2 (“wild type”)	7010	0	S142A/2,3-F2	5300	+1290 (compensating)	6590
2,3-F2	8300	+1290	S142A/3-CH3	5300	−820 (enhancing)	4480
3-CH3	6190	−820	T159E/2,3-F2	9200	+1290 (enhancing)	10490
3-OCH3	5070	−1940	T159E/3-OCH3	9200	−1940 (compensating)	7260

^aThe left side shows either the additive or subtractive effect of a particular chromophore substituent on the driving force. The right side shows the predicted driving force for each hybrid combining the effect of the point mutant and the chromophore substituent. Driving force values are extracted from ref 23. and calculated from eq 1 with an electronic coupling V₀ of 9530 cm⁻¹. The chromophore modified with OCH₃ possesses a somewhat smaller V₀ than the unsubstituted counterpart,²³ but for the current purpose the same V₀ is used for driving force evaluation.