Figure 3 Observed electron density for the acarbose-derived nonasaccharide bound to the Bacillus sp. BHA -amylase at 2.1  Å resolution. The maps shown are a maximum-likelihood (Murshudov et al., 1997) and A (Read, 1986) weighted 2Fobs - Fcalc synthesis contoured at 0.3  e  Å3 (approximately 1) in red and an Fobs - Fcalc difference map (at 3) in which the O6 atoms were not included in the refinement or phase calculation in blue. The difference map clearly reveals density for O6 atoms in the -6, -4, -3, -2, -1, +1, +2, and +3 sites (see Fig. 1c for interpretation and comparison).

© International Union of Crystallography 2005