Wednesday, September 13, 2017 at 1:00pm
"Pushing the envelope for biological SAXS: developing novel techniques, instrumentation, and software"
Abstract: Small angle X-ray scattering (SAXS) is an increasingly popular technique for obtaining structural information from biological macromolecules and complexes in solution. With the growing popularity has come an expanding arsenal of different experimental approaches and analysis techniques to allow SAXS to address challenging biological problems. This talk will focus on my contributions to this arsenal, and is divided into three parts.
First I will discuss the possibility of millisecond data collection at ultra-bright X-ray sources and how it may reduce radiation damage in SAXS. Radiation damage places serious constraints on SAXS experiments, and many current synchrotron beamlines have to attenuate their beam to collect undamaged data. My experiments, carried out at the European Molecular Biology (EMBL) P12 bioSAXS beam line at DESY (Hamburg, Germany), show that it is possible to collect data faster than some of the damage can physically manifest in the system, effectively 'outrunning' the radiation damage. This paves the way to full utilization of ultra-bright beamlines for routine SAXS. These experiments also provide insight into the timescales of the fundamental radiation chemistry and physics involved in the damage process.
The second part of the talk will focus on novel methods of SAXS data collection being developed at MacCHESS and Cornell. I will discuss my development of millisecond capable time resolved SAXS instrumentation at the G1 beamline, including preliminary tests of this system using the lysozyme refolding reaction, and how this might evolve in the future. I will also briefly touch on the current status and future possibilities of low temperature SAXS (cryoSAXS). In the last part of the talk, I will showcase my continued development of the BioXTAS RAW analysis software for SAXS that is used by at least five beamlines (and many individual investigators) around the world. This will cover improvements and additions to the software, such as the evolving factor analysis method, as well as future directions for the software.