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. Author manuscript; available in PMC: 2020 Oct 14.
Published in final edited form as: J Comput Aided Mol Des. 2020 Feb 12;34(5):561–573. doi: 10.1007/s10822-020-00280-7

Table 2.

State energies derived from pKas in Table 1 using different reference states or reference pHs.

pH =0 pH=7 pH=0 ΔΔG°jC - ΔΔG°jB
State j ΔmjB ΔG°jB ΔG°’jB ΔmjC ΔG°jC
A 1 2.17 9.17 2 −3.44 −5.61
B 0 0 0 1 −5.61 −5.61
C −1 5.61 −1.39 0 0 −5.61
D −2 19.37 5.37 −1 13.77 −5.61

With B as the reference state ΔG°jB and ΔG°jC obtained with eqn 2b given pKAB and pKCB; ΔG°DB = ΔG°DC+ΔG°CB (Table 1). ΔG°’jB, the relative state energies with the reference pH=7, is obtained with eqn 2c. When C is the reference state the ΔG° relative to states B and D are obtained directly from the reported pKas using equation 2b. ΔG°AC = ΔG°AB+ΔG°BC. There is a constant offset for all ΔG°s moving from a system that uses state B or state C as the reference state. ΔG represents unitless free energies where a unit change in ΔG yields a 10-fold population change.