Fig. 4From: 3D-QSAR study of steroidal and azaheterocyclic human aromatase inhibitors using quantitative profile of protein–ligand interactionsClose-up view of the aromatase active site in complex with 4β-acetoxy 5-androstene-17-one (a) and 6α-n-hexyl 4-androstene-3,17-dione (b). The protein backbone is rendered in rainbow color (N terminus, blue; C terminus, red): carbon, gray; nitrogen, blue; oxygen, red; iron, orange. The ligand carbons are shown in magenta and optimized flexible Thr310 (a) and Phe221 (b) residues are shown in cyan. The hydrogen bonds between the ligands and active site residues are drawn as green dashed linesBack to article page