Figure 2.

The figure depicts the native and mutated residues (shown in balls-and-stick model) of the variants R155K and D168A in the structure of NS3 protease (color rainbow). As can be inferred, the change in the residues introduced larger amino acid groups for R155K that will decrease the binding efficiency of drug molecules due to more steric hindrances. Also, the introduction of nonpolar groups for D168A transition will contribute to only weaker molecular interactions and thus reduced binding.