Following from this, we shift our focus to characterizing the role each mutation has had towards altering the conformational sampling of the W50 side chain, starting with the active site mutation I7D. By analyzing the strength of several interactions against the distributions of the W50 χ2 dihedral angle in simulations of the R1 and R4 variants (Figure ), we can identify how the I7D mutation favors the "C" conformational state (as summarized in Figure ). Specifically, in the R4 variant, the I7D and K222 side chains form a salt bridge which in turn disrupts K222's salt bridge with E101, which, in addition to elevating the pKa of E101, also enables the W50 side chain to form a hydrogen bond with E101 (Figure ), stabilizing the new conformation. The I7D-K222 interaction was ~6 times stronger in the "C" state and the K222-E101 was ~12 times weaker in the "C" state, with both interactions having a mutual information score of ~0.5 and linear correlation of ~|0.7| (Figure ). In contrast, the R1 K222-E101 salt bridge is substantially less correlated to the conformation of W50, with a mutual information score of just 0.09 and a linear correlation of -0.31 (Figure ).