title: Uridine as a new scavenger for synchrotron-based structural biology techniques.
abstract: Macromolecular crystallography (MX) and small-angle X-ray scattering (SAXS) studies on proteins at synchrotron light sources are commonly limited by the structural damage produced by the intense X-ray beam. Several effects, such as aggregation in protein solutions and global and site-specific damage in crystals, reduce the data quality or even introduce artefacts that can result in a biologically misguiding structure. One strategy to reduce these negative effects is the inclusion of an additive in the buffer solution to act as a free radical scavenger. Here the properties of uridine as a scavenger for both SAXS and MX experiments on lysozyme at room temperature are examined. In MX experiments, upon addition of uridine at 1 M, the critical dose D1/2is increased by a factor of ∼1.7, a value similar to that obtained in the presence of the most commonly used scavengers such as ascorbate and sodium nitrate. Other figures of merit to assess radiation damage show a similar trend. In SAXS experiments, the scavenging effect of 40 mM uridine is similar to that of 5% v/v glycerol, and greater than 2 mM DTT and 1 mM ascorbic acid. In all cases, the protective effect of uridine is proportional to its concentration.
authors.affiliation: ALBA Synchrotron, Carrer de la llum 2-26, 08290 Cerdanyola del Vallès, Barcelona, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Crosas
authors.affiliation: ALBA Synchrotron, Carrer de la llum 2-26, 08290 Cerdanyola del Vallès, Barcelona, Spain.
authors.forename: Albert
authors.initials: A
authors.lastname: Castellvi
authors.affiliation: ALBA Synchrotron, Carrer de la llum 2-26, 08290 Cerdanyola del Vallès, Barcelona, Spain.
authors.forename: Isidro
authors.initials: I
authors.lastname: Crespo
authors.affiliation: ALBA Synchrotron, Carrer de la llum 2-26, 08290 Cerdanyola del Vallès, Barcelona, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Fulla
authors.affiliation: ALBA Synchrotron, Carrer de la llum 2-26, 08290 Cerdanyola del Vallès, Barcelona, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Gil-Ortiz
authors.affiliation: EMBL, c/o DESY, Notkestrasse 85, 22607 Hamburg, Germany.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Fuertes
authors.affiliation: ALBA Synchrotron, Carrer de la llum 2-26, 08290 Cerdanyola del Vallès, Barcelona, Spain.
authors.forename: Christina S
authors.initials: CS
authors.lastname: Kamma-Lorger
authors.affiliation: ALBA Synchrotron, Carrer de la llum 2-26, 08290 Cerdanyola del Vallès, Barcelona, Spain.
authors.forename: Marc
authors.initials: M
authors.lastname: Malfois
authors.affiliation: ALBA Synchrotron, Carrer de la llum 2-26, 08290 Cerdanyola del Vallès, Barcelona, Spain.
authors.forename: Miguel A G
authors.initials: MA
authors.lastname: Aranda
authors.affiliation: ALBA Synchrotron, Carrer de la llum 2-26, 08290 Cerdanyola del Vallès, Barcelona, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Juanhuix
mesh_terms: D011506:Proteins / Q000737:chemistry; D053838:Scattering, Small Angle; D017356:Synchrotrons; D014529:Uridine / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D011506:Proteins; D014529:Uridine
keywords: SAXS methods; free radical scavenger; macromolecular crystallography methods; radiation damage; reactive oxygen species