Fast SAXS Profile Computation with Debye Formula


MultiFoXS Help


If multiple PDB files were uploaded by the user, in addition to profile calculation for each structure, the server will also run enumeration and fitting of multiple structures to the input profile. Here is an example:
Input PDB files of DNA ligase III in several conformations (data from Cotner-Gohara et al. Biochemistry. 2010) input.zip
Input profile file iq.dat
In this example the crystal structure does not fit to the SAXS profile well (χ = 15.2, green profile). Several conformations are needed in order to explain the data. In solution the protein exists as a population of closed and open states. The fit to data improves as more open states are added (bar plot and fit plot) and for 4 states the χ value is 1.2. In the fit plot, the experimental data is shown as black dotes, the best scoring single structure fit is green, the 2-state fit is red, the 3-state fit is blue, and the 4-state fit is cyan. Click on show/hide buttons to display/hide the corresponding profiles. The best scoring 2-, 3-, and 4-state models are shown below in the corresponding colors.


Multi-state models from MultiFoXS

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Best scoring 2-state model χ = 2.53 c1 = 1.04 c2 = 0.49 show/hide weighted profile
PDB1: 1.pdb Rg = 29.04 w1 = 0.497
PDB2: 4.pdb Rg = 32.76 w2 = 0.503
Best scoring 3-state model χ = 1.54 c1 = 1.04 c2 = 1.07 show/hide weighted profile
PDB1: 1.pdb Rg = 29.04 w1 = 0.385
PDB2: 2.pdb Rg = 40.22 w2 = 0.402
PDB3: 3.pdb Rg = 29.6 w3 = 0.213
Best scoring 4-state model χ = 1.23 c1 = 1.04 c2 = 0.92 show/hide weighted profile
PDB1: 1.pdb Rg = 29.04 w1 = 0.430
PDB2: 3.pdb Rg = 29.6 w2 = 0.202
PDB3: 6.pdb Rg = 32.45 w3 = 0.161
PDB4: 7.pdb Rg = 44.87 w4 = 0.208