Fig. 2. Composite simulated-annealing omit electron density maps (1000K) contoured at 1.6σ showing the quality of the
crystallographic data in the loop region. The structures were initially solved using molecular replacement with a search
model missing the entire loop (residues 287–293), and the resolution limits for each structure are listed in Table 1. DMA
refers to the dimethyl arsenic adduct that is sometimes found on Cys290 due to the crystallization conditions [10].