Table 5.

Decomposition of the pair-wise interaction energy between the receptor-binding domain (RBD) and the angiotensin-converting enzyme 2 (ACE2) receptor for SARS-CoV-2 variants

Protein systems	Interaction enthalpy ${\mathrm{\Delta }}_{\mathit{interac}}{H}^{\mathrm{o}}$(kcal/mol)	Interaction entropy ${\mathrm{\Delta }}_{\mathit{interac}}{S}^{\mathrm{o}}$(kcal/(mol.K)	Interaction gibbs free energy ${\mathrm{\Delta }}_{\mathit{interac}}{G}^{\mathrm{o}}$(kcal/mol)	$\mathrm{\Delta }{\mathrm{\Delta }}_{\mathit{interac}}{G}^{\mathrm{o}}$(kcal/mol)
Wt	– 233 (4)	0.460 (0.013)	– 371 (4)	0
Alpha	– 220 (13)	0.486 (0.043)	– 366 (16)	6
Beta	– 172 (9)	0.578 (0.030)	– 346 (9)	26
Gamma	– 145 (7)	0.372 (0.023)	– 257 (7)	115
Delta	– 235 (11)	0.546 (0.037)	– 399 (11)	–28
Eta	– 207 (13)	0.524 (0.043)	– 365 (13)	7
Kappa	– 217 (16)	0.429 (0.053)	– 346 (16)	26
Omicron	– 380 (14)	0.461 (0.047)	– 519 (14)	–148

$\mathrm{\Delta }{\mathrm{\Delta }}_{\mathit{interac}}{G}^{\mathrm{o}}$ energies were calculated using Eq. 2 for 27 °C. The uncertainties energies and entropies computed using block average method described in Sect. 2.2 are given in parenthesis