Dear all
I have a 2.0 angstrom diffraction data of a 24 amino acid collagen triple helix (a trimer) indexed to P1 space group. The ASU estimation is as follows
+-----------------------------------------------------------------------------+
| N(mol) Prob(N) Prob(N) Vm Vs Mw |
| for resolution overall A**3/Da % solvent Da |
+-----------------------------------------------------------------------------+
| 3 0.0009 0.0072 7.91 84.44 6786.00 |
| 6 0.0530 0.1440 3.95 68.88 13572.00 |
| 9 0.5740 0.6089 2.64 53.32 20358.00 |
| 12 0.3651 0.2354 1.98 37.77 27144.00 |
| 15 0.0071 0.0044 1.58 22.21 33930.00 |
+-----------------------------------------------------------------------------+
The self-rotation map is shown below. This is my first crystal structure and I am really confused on how to correlate the self-rotation function with possible ASU content. For exmple, a single peak at chi=60ยบ suggest six molecules in the ASU but that would lead to improbably low solvent content. Peaks at chi=60, 90 and 120 coaxial with one peak at chi=180 are perpendicular to the 8 two-fold NCS peaks at chi=180. I cannot think of a molecular arrangment that would simultaneous satisfy the
peaks observed in the self-rotation map.
To add to the misery, Xtriage suggests that the space group assignment is incorrect. It should be C 1 2 1 which would correspond well with the apparently two-fold crystallographic peaks observed at the edges in chi=180. But would it correlate with a single peak observed at chi=60 suggesting six molecules in the ASU?
Being my first crystal structure, I would appreciate any help or suggestions as to the interpretation of the self-rotation map.
Thank you
Abhishek
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