Small-angle scattering (SAS) allows insights into the overall conformation, oligomerization and binding, as well as dynamics of biomolecules in solution. Small-angle X-ray scattering (SAXS) does not rely on any labeling, thus not impeding the native behavior of the molecules.
An in-house SAXS instrument (Rigaku BioSAXS-1000) is available within the Department of Biosciences for batch measurements. For larger molecules and systems with limited stability, synchrotron SAXS beamlines (e.g. at ESRF) provide the option of size exclusion-coupled SAXS (SEC-SAXS).
In-house instrument
Our in-house SAXS instrument (Rigaku BioSAXS-1000) offers high availability and allows for fast turnaround times. This is especially useful for screening large numbers of samples and conditions, also in preparation for synchrotron beamtime or small-angle neutron scattering (SANS).
To this end, it is equipped with a 96-well sample changer. At typical SAS concentrations (1 - 10 mg/ml), a single sample is measured for 2 hours. The instrument can record data down to q = 0.0067 Å, roughly corresponding to a maximum particle size of 450 Å.
SAXS at synchrotrons
For systems that exceed the capabilities of our in-house instrument, we regularly utilize SAXS beamlines at synchrotron light sources. This might be necessary in particular if:
- your system is too large
- your system is heterogeneous (oligomers, aggregates) and the species can be separated by SEC: At a synchrotron, size exclusion-coupled SAXS can be performed
Small-angle neutron scattering (SANS)
The elucidation of the structures of complexes may be especially aided by contrast variation in SANS. This method allows to modulate the scattering contrast, and thus the visibility, of certain subunits through deuteration. Therefore, the spatial arrangement of the different subunits can be determined.