Predicted binding modes of the studied compounds within the PDE3A binding site.

<p>Each inhibitor series <b>1</b>–<b>5</b> is shown separately: set <b>1</b> in (a), set <b>2</b> in (b), set <b>3</b> in (c), set <b>4</b> in (d), and set <b>5</b> in (e). Ligands are shown in thin tubes representation with magenta carbons. Protein residues and metal-coordinating waters are displayed in thick tubes, and magnesium ions as van der Waals spheres. PDE3A residues are shown in gray, ligand binding residues in pale orange, and metal binding residues in light gray. Dashed black lines indicate H-bonds and cyan dashed lines denote π-stacking interactions. The tertiary structure is shown in white ribbons.