Since the double mutants D253E-H254R and D253E-I255G induced changes in the interactions near the OPH active site and the single mutant D253E expanded the interaction network within the binding site, we decided to explore whether positions 254 and 255 are also important for the stability of the binding site. Thus, we designed two single mutants (H254S and I255S), where we changed the properties of the basic residue at position 254 and the non-polar residue at position 255, by replacing each of them with an apolar amino acid: Serine. Next, we performed MD simulations on the two complexes: OPH:H254S and OPH:I255S. We inspected the residues' interactions in and near the binding site during the MD simulations and compared the hydrogen bonds found to those identified during the MD simulations on the WT complex.