data processing and ab initio analysis
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Small angle X-ray scattering Data processing and ab initio analysis Al Kikhney EMBL Hamburg Outline 3D 2D 1D Experiment design and data reduction Exposure time, radiation damage Background subtraction Dilution


  1. DAMMIN IN Svergun, D.I. (1999) Biophys J 76 • Variable number of “dummy atoms” on a fixed grid • Scattering is computed using spherical harmonics • Monte-Carlo type search • Fixed search space (defined by D max ) • Provides volume/molecular weight estimate • Idea first published by P. Chacón et al. (1998) Biophys J 74

  2. DAMMIF IF Franke, D. and Svergun, D.I. (2009) J Appl Cryst 42, 342 – 346 • Variable number of “dummy atoms” on a fixed grid • Scattering is computed using spherical harmonics • Monte-Carlo type search • Expandable search space • Provides volume/molecular weight estimate • 40 time faster than DAMMI N (D. I. Svergun (1999) Biophys J 76)

  3. https://www.embl-hamburg.de/biosaxs/atsas-online/dammif.php

  4. Ab initio shape reconstruction Single phase shape Fit one data set determination

  5. Ab initio shape reconstruction: multi-phase dummy atom modelling Fit data from several subunits

  6. https://www.embl-hamburg.de/biosaxs/atsas-online/monsa.php

  7. Ab initio reconstruction: dummy residue modelling Number of dummy residues = number of residues on the protein 3.8 Å D max GASBOR Svergun, D.I., Petoukhov, M.V, Koch, M.H.J. (2001) Biophys J 80, 2946 – 2953.

  8. Ab initio reconstruction: dummy residue modelling log 10 I(q) target curve calculated from the model q, nm -1

  9. Ab initio reconstruction: dummy residue modelling log 10 I(q) target curve calculated from the model q, nm -1

  10. Ab initio reconstruction: dummy residue modelling log 10 I(q) target curve calculated from the model q, nm -1

  11. GASBOR Svergun, D.I., Petoukhov, M.V, Koch, M.H.J. (2001) Biophys J 80, 2946 – 2953 • Fixed number of “dummy residues” • Distances to neighbor “residues” like in proteins

  12. GASBOR Svergun, D.I., Petoukhov, M.V, Koch, M.H.J. (2001) Biophys J 80, 2946 – 2953 • Fixed number of “dummy residues” • Distances to neighbor “residues” like in proteins • Fixed search space • Scattering is computed using Debye formula • Higher angles used (up to 12 nm -1 ) • Only for proteins smaller than 660 kDa

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