Figure 25 Cross-crystal averaging in haemagglutinin-neuraminidase (HN). (a) The unit cell showing the 6.0  Å MIR map derived from eight heavy-atom derivatives contoured at 2.0, revealing two blobs corresponding to the two molecules in the asymmetric unit. (b) A section of the 2.0  Å map after phase extension and cross-crystal averaging over four non-isomorphous data sets.

© International Union of Crystallography 2003