Table 4.

Binding free energies (kcal/mol) and their components, calculated using MM/PBSA, for the interaction between ACE2 and A- Wild-type spike, B- Spike_N501Y, C- Spike_E484K and D- Spike_South_Africa_triple (K417N + E484K + N501Y).

Complex	Van der Waals Energy (kcal/mol)	Electrostatic Energy (kcal/mol)	Polar Solvation Energy (kcal/mol)	SASA Energy (kcal/mol)	Binding Energy (kcal/mol)
Wild-type Spike/ACE2 (control)	−91.56 ± 0.56	−317.31 ± 1.64	132.47 ± 2.48	−10.75 ± 0.07	−287.25 ± 2.10
Spike_N501Y/ACE2	−96.74 ± 0.70	−324.27 ± 2.00	123.98 ± 3.01	−10.65 ± 0.08	−307.62 ± 2.41
Spike_E484K/ACE2	−97.95 ± 0.54	−560.16 ± 2.37	174.02 ± 2.41	−11.25 ± 0.06	−495.37 ± 2.64
Spike_South_Africa_triple (K417N + E484K + N501Y)/ACE2	−120.46 ± 1.06	−418.06 ± 1.44	187.42 ± 3.38	−12.85 ± 0.11	−363.98 ± 2.34