Structure of cathepsin D bound to pepstatin. Proteolytic domains in this family display two nearly-symmetrical barrel lobes. The catalytic site is formed by two aspartic acid side chains, one from each lobe (residues 33 and 231). According to the proposed catalytic mechanism, both catalytic side chains activate a water molecule which in turns acts as a nucleophile and attacks the target peptidic bond.
Structures are rendered as ribbons. Catalytic and catalytic metal-complexing residues are shown as neons. Inhibitors are displayed as space filling spheres.
Carbons are shown in light gray, hydrogens in cyan, oxygens in red, nitrogens in blue, and sulfurs in yellow.
Left-click and drag to rotate the protease. Right-click and drag up/down to zoom in/out. Click with both buttons and drag to move the protease. Use the upper bar to get different views and for display options. For a close-up of the catalytic site, choose the cat_site view.
Once you have clicked inside the structure window, you can use the keyboard to hide/show objects:
'1' toggles the ribbon. '2' toggles the inhibitor. '3' toggles the catalytic residues.