What is SAXS?

Small-angle X-ray scattering (SAXS) is a technique used to derive low resolution structural information about the shape, size, electronic density, molecular weight and conformational changes of macromolecules in solution by taking advantage of the scattering intensities at different angles.

Tutorial sections

• Instrumentation :
  • Overview of the instrumentation - to be familiar with the equipment in the laboratory
  • Software - software used by the instrument
  • Maintenance - basic maintenance procedures
• SAXS experiment :
  • Running a SAXS experiment - first steps into data acquisition
  • SEC-SAXS setup - data acquisition in SEC-SAXS mode
• Data processing Data processing:
  • Basic processing of SAXS data - initial data analysis and sample quality assessment
  • Advanced processing of SAXS data - calculation of the pairwise distribution function
  • Dealing with SEC-SAXS data - analyzing your SEC-SAXS data
• Ab initio modeling :
  • Modeling with DAMMIF - dummy atom modeling from SAXS data using DAMMIF
  • Modeling with DENSS - electron density modeling from SAXS data using DENSS

References for this tutorial

Demonstration data

If you would like to explore this tutorial with demonstration data, you can download these datasets:

• lysozyme dataset (ZIP file) for batch mode analysis. More experimental details and data organization on the GitHub page.
• BSA dataset (ZIP file) for SEC-SAXS analysis. More experimental details and data organization on the GitHub page.

Software required

The instructions on how to install individual software on your personal computer are details on their respective websites.

• BioXTAS RAW
• ATSAS manuals
• DENSS manual

Alternatively, the Structural Biology Platform has computers available where recent versions are installed. Access to the computer room is controlled by access codes. Contact Normand Cyr in order to obtain a code.

Scientific literature

• Jeffries CM, et al (2016). Preparing monodisperse macromolecular samples for successful biological small-Angle X-ray and neutron-scattering experiments. Nature Protocols.
• Putnam CD, et al (2007). X-ray solution scattering (SAXS) combined with crystallography and computation: defining accurate macromolecular structures, conformations and assemblies in solution. Quarterly Reviews of Biophysics
• Skou S, et al (2014). Synchrotron-based small-angle X-ray scattering of proteins in solution. Nature Protocols.
• Trewhella J, et al (2017). 2017 publication guidelines for structural modeling of small-angle scattering data from biomolecules in solution: an update. Acta Crystallographica Section D.