Figure 6

Water structure and anomalous difference density in the active site of the double mutant. The 2Fo-Fc electron density (blue mesh) is shown for the 5 water molecules contoured at 1 sigma and the two mutated alanine residues contoured at 1.5 sigma. When the anomalous difference density map was contoured at 3 sigma for the entire active site, strong difference density was observed only at the α-zinc atom (black sphere, red mesh) with a few noise contours near H61 and H232A. In particular, there was no anomalous difference density at Jβ, the putative β-metal site.