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1.  Experimental procedure for the characterization of radiation damage in macromolecular crystals 
Journal of Synchrotron Radiation  2011;18(Pt 3):381-386.
A novel automatic procedure to determine the sensitivity of macromolecular crystals to radiation damage is presented. The information extracted from this procedure can be directly used for optimal planning of data collection or/and beamline calibration.
A reliable and reproducible method to automatically characterize the radiation sensitivity of macromolecular crystals at the ESRF beamlines has been developed. This new approach uses the slope of the linear dependence of the overall isotropic B-factor with absorbed dose as the damage metric. The method has been implemented through an automated procedure using the EDNA on-line data analysis framework and the MxCuBE data collection control interface. The outcome of the procedure can be directly used to design an optimal data collection strategy. The results of tests carried out on a number of model and real-life crystal systems are presented.
PMCID: PMC3268693  PMID: 21525646
BEST; EDNA; radiation damage
2.  The use of workflows in the design and implementation of complex experiments in macromolecular crystallography 
A powerful and easy-to-use workflow environment has been developed at the ESRF for combining experiment control with online data analysis on synchrotron beamlines. This tool provides the possibility of automating complex experiments without the need for expertise in instrumentation control and programming, but rather by accessing defined beamline services.
The automation of beam delivery, sample handling and data analysis, together with increasing photon flux, diminishing focal spot size and the appearance of fast-readout detectors on synchrotron beamlines, have changed the way that many macromolecular crystallography experiments are planned and executed. Screening for the best diffracting crystal, or even the best diffracting part of a selected crystal, has been enabled by the development of microfocus beams, precise goniometers and fast-readout detectors that all require rapid feedback from the initial processing of images in order to be effective. All of these advances require the coupling of data feedback to the experimental control system and depend on immediate online data-analysis results during the experiment. To facilitate this, a Data Analysis WorkBench (DAWB) for the flexible creation of complex automated protocols has been developed. Here, example workflows designed and implemented using DAWB are presented for enhanced multi-step crystal characterizations, experiments involving crystal re­orientation with kappa goniometers, crystal-burning experiments for empirically determining the radiation sensitivity of a crystal system and the application of mesh scans to find the best location of a crystal to obtain the highest diffraction quality. Beamline users interact with the prepared workflows through a specific brick within the beamline-control GUI MXCuBE.
PMCID: PMC3413211  PMID: 22868763
workflows; automation; data processing; macromolecular crystallography; experimental protocols; characterization; reorientation; radiation damage
3.  A preliminary neutron crystallographic study of an A-DNA crystal 
The LADI-III diffractometer at the Institut Laue–Langevin has been used to carry out the first neutron crystallographic study of a DNA oligonucleotide in the A conformation. The crystal size was 0.06 mm3, the smallest ever used successfully for a study of this type. The results provide evidence of unexpected base protonation and illustrate the opportunities that now exist for nucleic acid crystallography using both hydrogenated and perdeuterated oligonucleotides.
The LADI-III diffractometer at the Institut Laue–Langevin has been used to carry out a preliminary neutron crystallographic study of the self-complementary DNA oligonucleotide d(AGGGGCCCCT)2 in the A conformation. The results demonstrate the viability of a full neutron crystallographic analysis with the aim of providing enhanced information on the ion–water networks that are known to be important in stabilizing A-DNA. This is the first account of a single-crystal neutron diffraction study of A-DNA. The study was carried out with the smallest crystal used to date for a neutron crystallographic study of a biological macromolecule.
PMCID: PMC2650452  PMID: 19255472
neutron crystallography; A-DNA; LADI-III
4.  A preliminary neutron crystallographic study of thaumatin 
Preliminary neutron crystallographic data from the sweet protein thaumatin have been recorded using the LADI-III diffractometer at the Institut Laue Langevin (ILL). The results illustrate the feasibility of a full neutron structural analysis aimed at further understanding the molecular basis of the perception of sweet taste. Such an analysis will exploit the use of perdeuterated thaumatin.
A preliminary neutron crystallographic study of the sweet protein thaumatin is presented. Large hydrogenated crystals were prepared in deuterated crystallization buffer using the gel-acupuncture method. Data were collected to a resolution of 2 Å on the LADI-III diffractometer at the Institut Laue Langevin (ILL). The results demonstrate the feasibility of a full neutron crystallographic analysis of this structure aimed at providing relevant information on the location of H atoms, the distribution of charge on the protein surface and localized water in the structure. This information will be of interest for understanding the specificity of thaumatin–receptor interactions and will contribute to further understanding of the molecular mechanisms underlying the perception of taste.
PMCID: PMC2376403  PMID: 18453706
thaumatin; neutron diffraction; sweet proteins

Results 1-4 (4)