The present invention discloses a modified tumor necrosis factor-alpha converting enzyme (TACE) catalytic domain, that unlike the native TACE catalytic domain, is stable at high protein concentrations. The present invention further discloses methods for generating crystals of the modified TACE protein in protein-ligand complexes with a number of inhibitors. In addition, the present invention discloses methods of using the proteins, crystals and/or three-dimensional structures obtained to identify compounds that can modulate the enzymatic activity of TACE.