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![[Figure 4]](uz5012fig4mag.jpg)
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Figure 4
Experimental and simulated XS and PDDF profiles for γ-CD. (a) Superimposed simulated (blue) and experimental (red) XS profiles for γ-CD in water. Inset: the atomic model (PDB code 1d3c; Uitdehaag et al., 1999  ) of γ-CD used in the calculation. The eight glucose units of γ-CD are coded in different colors. (b) Whole and partial PDDFs for γ-CD. The upper PDDF curves were calculated from the full scattering profiles in (a) using GNOM: orange, from experimental data; and purple, from simulated data. The lower profiles were directly simulated from the atomic structure using the DD-PDDF approach: red, for all single glucose units; green, inter-unit distance correlations (Pcorr) for all nearest neighboring unit pairs; blue, inter-unit distance correlations for all unit pairs separated by one unit; cyan, inter-unit distance correlations for all unit pairs separated by two units; magenta, inter-unit distance correlations for all unit pairs separated by three units; and black, whole PDDF for γ-CD. The black curve equals the summation of red, green, blue, cyan and magenta. The negative values at long distances for both the whole and partial PDDFs arise from the negative net electron number of the CH2 group in water. The black and purple curves are very close if superimposing the (dashed) baselines. The peak at 17 Å in the experimental PDDF (orange) could arise from the solvation layer. The simulated PDDFs reproduced most of the features in the experimental one, and the partial structure simulations help identify their origins. XS data were collected at beamlines 12-ID-B and 12-ID-C of the Advanced Photon Source at Argonne National Laboratory. |
![[Figure 4]](uz5012fig4.jpg)
 | JOURNAL OF APPLIED CRYSTALLOGRAPHY |
ISSN: 1600-5767
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