X‐ray Solution Scattering Studies at the Life Sciences X‐ray Scattering (LiX) Beamline

Abstract

Solution small angle X-ray scattering (SAXS) is a method to characterize the behavior of particles such as proteins and protein complexes in solution. Information about particle size and shape as well as oligomeric state can be determined from the 1D scattering profiles. The life sciences X-ray scattering (LiX) beamline at NSLSII operates in two modes: I) X-ray imaging and II) solution scattering (BioSAXS). Here, we discuss the types of BioSAXS measurements performed, automation, remote collection, data processing and examples of user data. Static SAXS measurements are high throughput and managed with a sample handler, with room for up to 360 samples organized into 18-well holders. Each holder contains two rows that are connected to separate channels of a flow cell that aligns with the X-ray beam. As the sample flows into the channel and is illuminated by the X-ray beam, small angle (SAXS) and wide angle (WAXS) data is collected simultaneously on two detectors with a q-range of 0.006Å-1 to 3.2 Å-1. This type of measurement requires pure, monodisperse sample and for the case when mixed populations exist, such as dimers and monomers, static SAXS will produce poor data quality. Therefore, size exclusion chromatography coupled with SAXS (SEC-SAXS) should be considered to separate each species. At LiX, the center flow channel is connected to an HPLC system, which allows for seamless integration of SEC-SAXS into the workflow without having to make changes to the beamline hardware setup. Once data is collected, it is packaged into HDF5 format and automatically processed. Data is transferred to users via Globus. We now offer remote collection and users can ship samples in holders or 96-well plates. Samples sent in plates are loaded into an Opentrons liquid handling system and transferred into sample holders. Additionally, having the Opentrons allow us to manipulate sample conditions through dilution, mixing and/or screening right before measurement.