view article

Figure 8
(a) A stereoview of an idealized F-centred cubic unit cell, a = 196.6 Å, with F23 crystallographic symmetry (48 symmetry operators) applied to two schematic dodecamers coloured black and red. This symmetry represents the basic arrangement of dodecamers in the P1 structure, with crystal contacts formed at the twofold axes within the each dodecamer so that, for example, the central dodecamer (red) forms crystal contacts with six other dodecamers (black) all at 90° from each other. (b) The packing in (a) leaves space for four dodecamers within the unit cell, which form a second lattice of dodecamers equivalent to the first but involving a translation of (1/4, 1/4, 1/4) from the origin. This arrangement is equivalent to F4132 crystallographic symmetry (96 symmetry operators), which when applied to two monomers generates the entire 192 molecules found in the P1 crystal structure. (c) A comparison of the 16 NCS dodecamers in the P1 structure (coloured uniquely) with the idealized F4132 cubic structure as shown in (b). This highlights the general agreement between the observed and idealized structures, while also illustrating the small differences in orientation in individual dodecamers which break the higher symmetry.

Journal logoBIOLOGICAL
ISSN: 1399-0047
Follow Acta Cryst. D
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds