Fast SAXS Studies of Sensitive Biological Samples

Small-angle X-ray scattering (SAXS) measurements of low-concentrated and highly radiation-sensitive biological samples using line collimation avoid radiation damages and ensure a short measurement time for analyzing the low-resolution 3D structure of proteins.

SAXS of biological samples

Small-angle X-ray scattering (SAXS) provides valuable structural information of biological samples such as proteins, RNA, DNA including their complexes. A main advantage compared to other methods is that with SAXS the proteins are measured in solution, i.e. under near-native conditions.

However, obtaining high-quality SAXS data of biological samples is often challenging due to low sample concentrations resulting in a low signal-to-noise of the scattering curves and low sample stability. In addition, some sensitive proteins are prone to radiation damage, so in case of an intense point-collimated X-ray beam such the structure of such proteins might get damaged before SAXS data of sufficient quality for further evaluation can be collected.

Line collimation offers several advantages to resolve and overcome these challenges:

  • an increased signal-to-noise ratio compared to point collimation,
  • excellent sample stability (no sample deterioration by radiation damage),
  • high resolution (i.e. smaller accessible q-vectors) along with high flux ensuring short measurement times.

For data analysis and structural studies the line-smeared SAXS data were evaluated using standard programs (SAXSanalysis, GIFT1 and DAMMIF2).

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