Abstract
This work reports the instrumentation and software implementation at the Life Science X-ray Scattering (LiX) beamline at NSLS-II in support of biomolecular solution scattering. For automated static measurements, samples are stored in PCR tubes and grouped in 18-position sample holders. Unattended operations are enabled using a six-axis robot that exchanges sample holders between a storage box and a sample handler, transporting samples from the PCR tubes to the X-ray beam for scattering measurements. The storage box has a capacity of 20 sample holders. At full capacity, the measurements on all samples last for ∼9 h. For in-line size-exclusion chromatography, the beamline-control software coordinates with a commercial high-performance liquid chromatography (HPLC) system to measure multiple samples in batch mode. The beamline can switch between static and HPLC measurements instantaneously. In all measurements, the scattering data span a wide q-range of typically 0.006-3.2 Å-1. Functionalities in the Python package py4xs have been developed to support automated data processing, including azimuthal averaging, merging data from multiple detectors, buffer scattering subtraction, data storage in HDF5 format and exporting the final data in a three-column text format that is acceptable by most data analysis tools. These functionalities have been integrated into graphical user interfaces that run in Jupyter notebooks, with hooks for external data analysis software.
Highlights
IntroductionAs we focus the scope of the study to solution scattering and microbeam mapping, which are both conducted in transmission geometry with the samples under ambient pressure and requiring similar coarse positioning, the common interface for these experimental modules is provided by a coarse positioning stage with x (horizontal and perpendicular to the beam) and z (along the beam) degrees of freedom
The Life Science X-ray Scattering (LiX) beamline was constructed at NSLS-II as part of the Advanced Beamlines for Biological Investigations using X-rays (ABBIX) project (Fuchs et al, 2014; DiFabio et al, 2016) funded by the National Institute of Health
As we focus the scope of the study to solution scattering and microbeam mapping, which are both conducted in transmission geometry with the samples under ambient pressure and requiring similar coarse positioning, the common interface for these experimental modules is provided by a coarse positioning stage with x and z degrees of freedom
Summary
As we focus the scope of the study to solution scattering and microbeam mapping, which are both conducted in transmission geometry with the samples under ambient pressure and requiring similar coarse positioning, the common interface for these experimental modules is provided by a coarse positioning stage with x (horizontal and perpendicular to the beam) and z (along the beam) degrees of freedom. The scattering data typically span a continuous range of scattering vectors, q = 4 sin /, from 0.006 A À1 to 3.2 A À1 (see examples in Section 4), sufficient for practically all types of solution samples. We describe the instrumentation for automated static measurements and in-line size-exclusion chromatography (SEC) as well as the software for data collection and processing
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