The molecular dynamics program NAMD [ 27 ] was used to minimize the P450c17:cyt b5 complex. This complex was initially solvated with TIP3P water using the Solvate plugin within VMD version . The rotate to minimize volume was selected, the boundary reduced to and the box padding increased to 20 Å in all directions; all other parameters were kept at default. Charges were then neutralized with NaCl using the autoionize plugin within VMD version using default settings. Each structure was minimized and equalized for 1 nanosecond (2 femtosecond time step) under the CHARMM27 all-atom force field at 298 K. Langevin dynamics were used with group pressure and Langevin piston were turned on. Trajectory snapshots were collected every picosecond. After approximately 200 picosconds, the average RMSD had leveled to approximately 2 Å and analysis was conducted after this time point. Hydrogen bond occupancy was calculated using the Hydrogen Bond plugin in VMD version with a donor-acceptor distance at Å and an angle cutoff of 20°. Detailed information was then selected to be included in the calculation for ‘All H-bonds’.