Table 2.

Standard Gibbs energies, Δ_BG⁰(37 °C), enthalpies, Δ_BH⁰(37 °C), and entropies, Δ_BS⁰(37 °C), of binding at 37 °C of spike protein to the ACE2 receptor, for various SARS-CoV-2 strains. Δ_BH⁰(37 °C) values were calculated using the van't Hoff equation (19), from the experimental K_B data (Table 1). Δ_BG⁰(37 °C) values were calculated from K_B values in Table 1, using equation (18). Calculated Δ_BH⁰(37 °C) and Δ_BG⁰(37 °C) values were combined to find Δ_BS⁰(37 °C) values, using equation (20). All the data are at 37 °C.

Mutations	ΔBG⁰(37 °C) (kJ/mol)	ΔBH⁰(37 °C) (kJ/mol)	ΔBS⁰(37 °C) (J/mol K)
Wild type (Hu-1)	−42.77	−79.34	−117.90
E484K	−43.22	−79.34	−116.45
N501Y	−49.04	−55.27	−20.08
E484K/N501Y	−50.06	−64.77	−47.42
K417 N/E484K/N501Y	−46.07	−73.22	−87.53
K417 N	−38.34	−102.47	−206.79