According to the results from binding free energy decomposition, the electrostatic difference of residue 85 causes the most significant thermodynamics effects on the binding of iFit4 to FKBP51 and FKBP52.  Furthermore, the importance of substructure units on iFit4 were further evaluated by unbinding pathway analysis and residue-residue contact analysis between iFit4 and the proteins. 
THERM