title: Imperfection and radiation damage in protein crystals studied with coherent radiation.
abstract: Fringes and speckles occur within diffraction spots when a crystal is illuminated with coherent radiation during X-ray diffraction. The additional information in these features provides insight into the imperfections in the crystal at the sub-micrometre scale. In addition, these features can provide more accurate intensity measurements (e.g. by model-based profile fitting), detwinning (by distinguishing the various components), phasing (by exploiting sampling of the molecular transform) and refinement (by distinguishing regions with different unit-cell parameters). In order to exploit these potential benefits, the features due to coherent diffraction have to be recorded and any change due to radiation damage properly modelled. Initial results from recording coherent diffraction at cryotemperatures from polyhedrin crystals of approximately 2 µm in size are described. These measurements allowed information about the type of crystal imperfections to be obtained at the sub-micrometre level, together with the changes due to radiation damage.
authors.affiliation: Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK.
authors.forename: Colin
authors.initials: C
authors.lastname: Nave
authors.affiliation: Division of Structural Biology, Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN, UK.
authors.forename: Geoff
authors.initials: G
authors.lastname: Sutton
authors.affiliation: Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK.
authors.forename: Gwyndaf
authors.initials: G
authors.lastname: Evans
authors.affiliation: Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK.
authors.forename: Robin
authors.initials: R
authors.lastname: Owen
authors.affiliation: Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK.
authors.forename: Christoph
authors.initials: C
authors.lastname: Rau
authors.affiliation: London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Robinson
authors.affiliation: Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK.
authors.forename: David Ian
authors.initials: DI
authors.lastname: Stuart
mesh_terms: D018360:Crystallography, X-Ray; D011506:Proteins / Q000737:chemistry / Q000528:radiation effects*
chemical_list: D011506:Proteins
keywords: coherent diffraction; crystal perfection; radiation damage