title: Breaking the radiation damage limit with Cryo-SAXS.
abstract: Small angle x-ray scattering (SAXS) is a versatile and widely used technique for obtaining low-resolution structures of macromolecules and complexes. SAXS experiments measure molecules in solution, without the need for labeling or crystallization. However, radiation damage currently limits the application of SAXS to molecules that can be produced in microgram quantities; for typical proteins, 10-20 μL of solution at 1 mg/mL is required to accumulate adequate signal before irreversible x-ray damage is observed. Here, we show that cryocooled proteins and nucleic acids can withstand doses at least two orders of magnitude larger than room temperature samples. We demonstrate accurate T = 100 K particle envelope reconstructions from sample volumes as small as 15 nL, a factor of 1000 smaller than in current practice. Cryo-SAXS will thus enable structure determination of difficult-to-express proteins and biologically important, highly radiation-sensitive proteins including light-activated switches and metalloenzymes.
authors: School of Applied and Engineering Physics, Cornell University, Ithaca, New York, USA.
authors: Steve P
authors: SP
authors: Meisburger
authors: Matthew
authors: M
authors: Warkentin
authors: Huimin
authors: H
authors: Chen
authors: Jesse B
authors: JB
authors: Hopkins
authors: Richard E
authors: RE
authors: Gillilan
authors: Lois
authors: L
authors: Pollack
authors: Robert E
authors: RE
authors: Thorne
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000737:chemistry; D000818:Animals; D002021:Buffers; D002645:Chickens; D003080:Cold Temperature; D003451:Cryoprotective Agents / Q000494:pharmacology; D004307:Dose-Response Relationship, Radiation; D011092:Polyethylene Glycols / Q000737:chemistry; D053838:Scattering, Small Angle; D012996:Solutions; D058989:Vitrification / Q000187:drug effects; D014961:X-Ray Diffraction
chemical_list: D002021:Buffers; D003451:Cryoprotective Agents; D012996:Solutions; D011092:Polyethylene Glycols; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase