title: Using macromolecular-crystallography beamline and microfluidic platform for small-angle diffraction studies of lipidic matrices for membrane-protein crystallization.
abstract: Macromolecular-crystallography (MX) beamlines routinely provide a possibility to change X-ray beam energy, focus the beam to a size of tens of microns, align a sample on a microdiffractometer using on-axis video microscope, and collect data with an area-detector positioned in three dimensions. These capabilities allow for running complementary measurements of small-angle X-ray scattering and diffraction (SAXS) at the same beamline with such additions to the standard MX setup as a vacuum path between the sample and the detector, a modified beam stop, and a custom sample cell. On the 21-ID-D MX beamline at the Advanced Photon Source we attach a vacuum flight tube to the area detector support and use the support motion for aligning a beam stop built into the rear end of the flight tube. At 8 KeV energy and 1 m sample-to-detector distance we can achieve a small-angle resolution of 0.01A-1in the reciprocal space. Measuring SAXS with this setup, we have studied phase diagrams of lipidic mesophases used as matrices for membrane-protein crystallization. The outcome of crystallization trials is significantly affected by the structure of the lipidic mesophases, which is determined by the composition of the crystallization mixture. We use a microfluidic chip for the mesophase formulation andin situSAXS data collection. Using the MX beamline and the microfluidic platform we have demonstrated the viability of the high-throughput SAXS studies facilitating screening of lipidic matrices for membrane-protein crystallization.
authors.affiliation: Northwestern University, Synchrotron Research Center, LS-CAT, Bldg. 436A, 9700 S. Cass Ave., Argonne, IL 60439, USA.
authors.forename: E
authors.initials: E
authors.lastname: Kondrashkina
authors.forename: D S
authors.initials: DS
authors.lastname: Khvostichenko
authors.forename: S L
authors.initials: SL
authors.lastname: Perry
authors.forename: J
authors.initials: J
authors.lastname: Von Osinski
authors.forename: P J A
authors.initials: PJ
authors.lastname: Kenis
authors.forename: K
authors.initials: K
authors.lastname: Brister