. Author manuscript; available in PMC: 2020 Sep 25.

Published in final edited form as: J Am Chem Soc. 2019 Sep 11;141(38):15250–15265. doi: 10.1021/jacs.9b07152

Table 2.

Prediction of the Absorption Maximum of the GFP S65T R96M T203Y Mutant at Room Temperature, Comparing the Assumption That Either the Driving Force or the Transition Energy Is Additive^a

	driving force (cm⁻¹)	transition energy (cm⁻¹)
ih^mat(65T)·ih:loop:GFP R96M	10270	21645
s10:loop:GFP S65T	8080	20695
s10:loop:GFP S65T T203Y	4870	19666
	ih^mat(65T)·ih:loop:GFP R96M T203Y
assumption	driving force is additive	transition energy is additive
prediction	10270 − 8080 + 4870 = 7060	21645 – 20695 + 19666 = 20616
predicted transition energy (absorption maximum)	(7060² + 19060²)^1/2 = 20330 cm⁻¹ (492 nm)	20616 cm⁻¹ (485 nm)
observed transition energy (absorption maximum)	20240 cm⁻¹ (494 nm)

To account for the minor differences between absorption maxima of circular permutants, we use the ih circular permutant as the basal value. The driving forces and transition energies are extracted from Tables S13 and S12, respectively. The conversion between transition energy and driving force is performed via eq S13 using V₀ = 9530 cm⁻¹ (Figure 8).