Fig. 4.

Density functional theory calculations of binding and solvation free energies of 5 and 5-SH. a Optimized geometries and energies of 5 and 5-SH (modeled as truncated versions of 1–4) in the presence of two imidazoles (the side chains of H303 and H340) in the gas phase. The units of bond length (shown as dotted lines) and Gibbs energies are Å and kcal mol⁻¹, respectively. b Optimized geometries and energies of 5 and 5-SH bound to the sides chains of three fixed amino acids (H303, H340, Q163) in the gas phase. c Free energies of solvation of 5 and 5-SH