Open AccessUpgrade of MacCHESS facility for X‐ray scattering of biological macromolecules in solution
Author(s) -
Acerbo Alvin Samuel,
Cook Michael J.,
Gillilan Richard Edward
Publication year - 2015
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s1600577514020360
Subject(s) - beamline , upgrade , synchrotron , scattering , small angle x ray scattering , storage ring , wiggler , optics , sample (material) , small angle scattering , usable , detector , materials science , beam (structure) , physics , computer science , cathode ray , nuclear physics , electron , world wide web , thermodynamics , operating system
X‐ray scattering of biological macromolecules in solution is an increasingly popular tool for structural biology and benefits greatly from modern high‐brightness synchrotron sources. The upgraded MacCHESS BioSAXS station is now located at the 49‐pole wiggler beamline G1. The 20‐fold improved flux over the previous beamline F2 provides higher sample throughput and autonomous X‐ray scattering data collection using a unique SAXS/WAXS dual detectors configuration. This setup achieves a combined q ‐range from 0.007 to 0.7 Å −1 , enabling better characterization of smaller molecules, while opening opportunities for emerging wide‐angle scattering methods. In addition, a facility upgrade of the positron storage ring to continuous top‐up mode has improved beam stability and eliminated beam drift over the course of typical BioSAXS experiments. Single exposure times have been reduced to 2 s for 3.560 mg ml −1 lysozyme with an average quality factor I /σ of 20 in the Guinier region. A novel disposable plastic sample cell design that incorporates lower background X‐ray window material provides users with a more pristine sample environment than previously available. Systematic comparisons of common X‐ray window materials bonded to the cell have also been extended to the wide‐angle regime, offering new insight into best choices for various q ‐space ranges. In addition, a quantitative assessment of signal‐to‐noise levels has been performed on the station to allow users to estimate necessary exposure times for obtaining usable signals in the Guinier regime. Users also have access to a new BioSAXS sample preparation laboratory which houses essential wet‐chemistry equipment and biophysical instrumentation. User experiments at the upgraded BioSAXS station have been on‐going since commissioning of the beamline in Summer 2013. A planned upgrade of the G1 insertion device to an undulator for the Winter 2014 cycle is expected to further improve flux by an order of magnitude.