The S-HL of the apoenzyme model comprised of Cys493 and Gly829 residues with adjacent fragments of the main chain (Fig. ). The S-HL of the holoenzyme model was extended by the residue of Gln707 as well as fumarate and toluene with respect to that of apoenzyme. The B-HL comprised of S-HL extended by all residues penetrating 5 Å radius of Gly829 and Cys493