Figure 3.

RNase II D209N SIRAS statistics. (a) As a zero signal, 〈d′′/sig〉 is about 0.8 (SHELXC output documentation), the SeMet diffraction data (blue) is shown to contain anomalous signal until its resolution cutoff, in contrast to the mutant native data (red). (b) The Se site-occupancy profile indicates that the asymmetric unit contains only one RNase II molecule, as RNase II contains 16 Met residues in its sequence and residual occupancies of 0.2 indicate noise peaks (Schneider & Sheldrick, 2002 ▶). (c) The space-group ambiguity was solved by SHELXE as the density-modification ‘map contrast’ statistics (Sheldrick, 2002 ▶) assuming space group P6₅ (red) clearly converged to a higher value when compared with that of its hand-inverted counterpart P6₁ (blue).