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Figure 3.
Figure 3. (a) Stereo view of the oligomeric architecture in
the P4[1]2[1]2 hK4-Zn form. One hK4 tetramer is located in the
asymmetric unit, highlighted by a transparent surface. This
arrangement is pseudo-symmetrical, in contrast to the
symmetrical tetramers of the P4 form. Only one zinc ion is
bound per tetramer, displayed as a pink ball with electron
density representing an anomalous Fourier map contoured at 3σ.
Molecules that are symmetry-related by a crystallographic 2-fold
axis are depicted in the same color. Both tetramers sit back to
back and contact each other with a flat interaction surface
resulting in an octameric assembly. (b) Top view of the octamer
from the P4[1]2[1]2 crystals rotated by 90° with respect to
(a). (c) Stereo representation of the asymmetric unit in the
hK4-Co P2[1] crystal form, which contains two hk4 octamers. One
cobalt ion is bound per pseudo-symmetrical tetramer, indicated
by an anomalous Fourier map.
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