Fig. 2.

Molecular modeling of DosS interaction with H₂S. (A) Calculated average association free energy profiles for H₂S and HS⁻ as a function of intermolecular distance between the DosS heme iron and sulfur. Free energy values were generated by employing 98 separate trajectories for H₂S and 89 trajectories for HS⁻ using a steered Molecular Dynamics (sMD) approach. (B–D) QM/MM MD simulation snapshots depicting the steps of a predicted proton transfer from H₂S to a nearby heme propionate group through a water bridge within 0.3 ps of MD. The QM subsystem atoms are shown in ball and stick representation.