The significance of residues around the binding site can be difficult to discern, as dynamic, noncovalent interactions between the substrate and protein are influential to docking. Three residues were selected along the binding pocket to capture the local environments at different depths, represented by noncovalent attachment to different types of residues (Figure ). The centroid of P30 was used as the binding reference to assess environment around the N-terminus. The C2 of the W441 residue was selected to parametrize the transmembrane domain between the N-terminus and the deeper region of the pocket. Finally, T111 was selected to probe the deeper region of the larger binding cavity. The default probe CycH_12 was unable to dock in the side pocket without overlapping with protein residues. Due to the narrow shape of the binding pocket, a linear probe (LinH_6) was utilized for protein descriptor calculation. Selectivity in Fe-Porphyrin Enzymes. Enzymes with engineered reactive sites can induce highly selective transformations. One well established transformation is intermolecular carbene insertion bio-catalyzed by Feporphyrin residues. The orientation and approach of the substrate to the Fe-carbene intermediate influences the observed selectivity, thus the residues around the porphyrin site are often specifically targeted for mutations.