'''STUDY ON RADIATION DAMAGE ON A CRYOCOOLED CRYSTAL. PART 4: STRUCTURE AFTER IRRADIATION WITH 27.2*10E15 PHOTONS'''
===STUDY ON RADIATION DAMAGE ON A CRYOCOOLED CRYSTAL. PART 4: STRUCTURE AFTER IRRADIATION WITH 27.2*10E15 PHOTONS===
==Overview==
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The high intensity of third-generation X-ray sources, along with the development of cryo-cooling of protein crystals at temperatures around 100 K, have made it possible to extend the diffraction limit of crystals and to reduce their size. However, even with cryo-cooled crystals, radiation damage becomes a limiting factor. So far, the radiation damage has manifested itself in the form of a loss of overall diffracted intensity and an increase in the temperature factor. The structure of a protein (myrosinase) after exposure to different doses of X-rays in the region of 20 x 10(15) photons mm(-2) has been studied. The changes in the structure owing to radiation damage were analysed using Fourier difference maps and occupancy refinement for the first time. Damage was obvious in the form of breakage of disulfide bonds, decarboxylation of aspartate and glutamate residues, a loss of hydroxyl groups from tyrosine and of the methylthio group of methionine. The susceptibility to radiation damage of individual groups of the same kind varies within the protein. The quality of the model resulting from structure determination might be compromised owing to the presence of radiolysis in the crystal after an excessive radiation dose. Radiation-induced structural changes may interfere with the interpretation of ligand-binding studies or MAD data. The experiments reported here suggest that there is an intrinsic limit to the amount of data which can be extracted from a sample of a given size.
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==About this Structure==
==About this Structure==
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[[Category: Radiation damage]]
[[Category: Radiation damage]]
[[Category: Radiolysis]]
[[Category: Radiolysis]]
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Revision as of 23:43, 30 June 2008
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STUDY ON RADIATION DAMAGE ON A CRYOCOOLED CRYSTAL. PART 4: STRUCTURE AFTER IRRADIATION WITH 27.2*10E15 PHOTONSSTUDY ON RADIATION DAMAGE ON A CRYOCOOLED CRYSTAL. PART 4: STRUCTURE AFTER IRRADIATION WITH 27.2*10E15 PHOTONS
Full crystallographic information is available from OCA.
ReferenceReference
Structural changes in a cryo-cooled protein crystal owing to radiation damage., Burmeister WP, Acta Crystallogr D Biol Crystallogr. 2000 Mar;56(Pt 3):328-41. PMID:10713520
