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Image-plate Detector System (image-plate + detector_system)
Selected AbstractsCharacterization of image plates for neutron diffractionJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5 2009Clive Wilkinson A method to measure the overall gain and point-spread function of an image-plate detector system (converter, phosphor, readout electronics) online from single-crystal diffraction patterns is derived. Only with a knowledge of these quantities can one estimate without bias the true standard deviations of the observed integrated intensities of Bragg reflections measured with such a detector. The gain corrected for the point-spread function should ideally be approximately 1.0 to avoid loss of data or precision due to the upper and lower limits of digitization of the diffraction patterns. The gain and the point-spread function are derived for several configurations of the three neutron Laue image-plate diffractometers, LADI, VIVALDI and LADI-III, at the Institut Laue,Langevin. The detective quantum efficiencies (DQE) of these instruments have been measured to be 0.16,(1), 0.57,(2) and 0.46,(3), respectively. It has also been found that the DQE is effectively constant for different times of exposure, despite the fading of the photostimulated luminescent signal during that time. While the results described in this paper concern neutron detection by image plates, the method is equally valid for other integrating detectors and radiations, e.g. CCD detectors and X-rays. [source] Purification, crystallization and preliminary crystallographic study of haemoglobin from camel (Camelus dromedarius): a high oxygen-affinity lowland speciesACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 8 2009M. Balasubramanian Haemoglobin is a prototypical allosteric protein that is mainly involved in the transportation of oxygen from the lungs to tissues and of carbon dioxide back to the lungs in an intrinsically coordinated manner to maintain the viability of cells. Haemoglobin from Camelus dromedarius provides an interesting case study of adaptation to life in deserts at extremely high temperatures. An ambition to unravel the integrated structural and functional aspects of the casual survival of this animal at high temperatures led us to specifically work on this problem. The present work reports the preliminary crystallographic study of camel haemoglobin. Camel blood was collected and the haemoglobin was purified by anion-exchange chromatography and crystallized using the hanging-drop vapour-diffusion method under buffered high salt concentration using PEG 3350 as a precipitant. Intensity data were collected using a MAR 345 dtb image-plate detector system. Camel haemoglobin crystallized in the monoclinic space group P21, with one whole biological molecule (,2,2) in the asymmetric unit and unit-cell parameters a = 52.759, b = 116.782, c = 52.807,Å, , = 120.07°. [source] Purification, crystallization and preliminary X-ray analysis of haemoglobin from ostrich (Struthio camelus)ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 7 2009S. S. Sundaresan Haemoglobin is a tetrameric protein that carries oxygen from the lungs to tissues and carbon dioxide from tissues back to the lungs. The oxygen-binding properties of haemoglobin are regulated through the binding of allosteric effectors. The respiratory system of avian species is unique and complex in nature when compared with that of mammals. In avian species, inositol pentaphosphate (inositol-P5) is present in the erythrocytes of the adult and is thought to be the major factor responsible for the relatively high oxygen affinity of the whole blood. The ostrich (Struthio camelus) is a large flightless bird which contains inositol tetrakisphosphate (inositol-P4) in its erythrocytes and its whole blood oxygen affinity is higher. Efforts have been made to explore the structure,function relationship of ostrich haemoglobin. Ostrich haemoglobin was purified using ion-exchange chromatography. Haemoglobin crystals were grown by the hanging-drop vapour-diffusion method using PEG 3350 as the precipitant in 50,mM phosphate buffer pH 7.2. Data were collected using a MAR345 image-plate detector system. The crystals of ostrich haemoglobin diffracted to 2.2,Å resolution. They belonged to the orthorhombic space group P212121 with one whole biological molecule in the asymmetric unit; the unit-cell parameters were a = 80.93, b = 81.68, c = 102.05,Å. [source] Purification, crystallization and preliminary X-ray diffraction studies on avian haemoglobin from pigeon (Columba livia)ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 2 2009Pon. Sathya Moorthy Haemoglobin is a physiologically significant metalloprotein that is involved in the exchange of gases for sustaining life. The respiratory system of birds is unique and complex compared with that of mammals. Many investigations of avian haemoglobins have revealed the presence of inositol pentaphosphate (IP5), a principal allosteric effector that is involved in regulation of their function. Structural investigations of avian haemoglobins are presently not adequate to explain their function. Efforts have been made in this direction in order to understand the oxygen-binding affinity involved in adapting to hypoxia in avian haemoglobins. Fresh whole blood was collected from pigeon (Columba livia) and purified using a DEAE cellulose anion-exchange chromatographic column. Crystallization of pigeon haemoglobin was accomplished using the hanging-drop vapour-diffusion method using PEG 3350 as a precipitant in 50,mM sodium acetate buffer pH 5.5 with 1,M NaCl. Data collection was carried out using a MAR345 image-plate detector system. The crystals diffracted to 2,Å resolution. Pigeon haemoglobin crystallizes in a triclinic space group, with two whole biological molecules in the asymmetric unit and with unit-cell parameters a = 55.005, b = 65.528, c = 104.370,Å, , = 78.742, , = 89.819, , = 65.320°. [source] Purification, crystallization and preliminary crystallographic study of low oxygen-affinity haemoglobin from cat (Felis silvestris catus) in two different crystal formsACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 3 2009M. Balasubramanian Haemoglobin is a metalloprotein which plays a major role in the transportation of oxygen from the lungs to tissues and of carbon dioxide back to the lungs. The present work reports the preliminary crystallographic study of low oxygen-affinity haemoglobin from cat in different crystal forms. Cat blood was collected, purified by anion-exchange chromatography and crystallized in two different conditions by the hanging-drop vapour-diffusion method under unbuffered low-salt and buffered high-salt concentrations using PEG 3350 as a precipitant. Intensity data were collected using MAR345 and MAR345dtb image-plate detector systems. Cat haemoglobin crystallizes in monoclinic and orthorhombic crystal forms with one and two whole biological molecules (,2,2), respectively, in the asymmetric unit. [source] | ||||||||||