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Title: Can radiation damage to protein crystals be reduced using small-molecule compounds?

Abstract

Free-radical scavengers that are known to be effective protectors of proteins in solution are found to increase global radiation damage to protein crystals. Protective mechanisms may become deleterious in the protein-dense environment of a crystal. Recent studies have defined a data-collection protocol and a metric that provide a robust measure of global radiation damage to protein crystals. Using this protocol and metric, 19 small-molecule compounds (introduced either by cocrystallization or soaking) were evaluated for their ability to protect lysozyme crystals from radiation damage. The compounds were selected based upon their ability to interact with radiolytic products (e.g. hydrated electrons, hydrogen, hydroxyl and perhydroxyl radicals) and/or their efficacy in protecting biological molecules from radiation damage in dilute aqueous solutions. At room temperature, 12 compounds had no effect and six had a sensitizing effect on global damage. Only one compound, sodium nitrate, appeared to extend crystal lifetimes, but not in all proteins and only by a factor of two or less. No compound provided protection at T = 100 K. Scavengers are ineffective in protecting protein crystals from global damage because a large fraction of primary X-ray-induced excitations are generated in and/or directly attack the protein and because the ratio of scavengermore » molecules to protein molecules is too small to provide appreciable competitive protection. The same reactivity that makes some scavengers effective radioprotectors in protein solutions may explain their sensitizing effect in the protein-dense environment of a crystal. A more productive focus for future efforts may be to identify and eliminate sensitizing compounds from crystallization solutions.« less

Authors:
 [1]; ; ;  [2];  [3]
  1. Kenyon College, Gambier, OH 43022 (United States)
  2. Cornell University, Ithaca, NY 14853 (United States)
  3. (United States)
Publication Date:
OSTI Identifier:
22351247
Resource Type:
Journal Article
Journal Name:
Acta Crystallographica. Section D: Biological Crystallography
Additional Journal Information:
Journal Volume: 67; Journal Issue: Pt 10; Other Information: PMCID: PMC3176623; PMID: 21931220; PUBLISHER-ID: be5169; OAI: oai:pubmedcentral.nih.gov:3176623; Copyright (c) International Union of Crystallography 2011; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0907-4449
Country of Publication:
Denmark
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; AQUEOUS SOLUTIONS; CRYSTALLIZATION; CRYSTALS; DAMAGE; ELECTRONS; EXCITATION; HYDRATION; HYDROGEN; IRON; LYSOZYME; MOLECULES; RADIATION EFFECTS; REACTIVITY; SAFETY

Citation Formats

Kmetko, Jan, Warkentin, Matthew, Englich, Ulrich, Thorne, Robert E., E-mail: ret6@cornell.edu, and Kenyon College, Gambier, OH 43022. Can radiation damage to protein crystals be reduced using small-molecule compounds?. Denmark: N. p., 2011. Web. doi:10.1107/S0907444911032835.
Kmetko, Jan, Warkentin, Matthew, Englich, Ulrich, Thorne, Robert E., E-mail: ret6@cornell.edu, & Kenyon College, Gambier, OH 43022. Can radiation damage to protein crystals be reduced using small-molecule compounds?. Denmark. doi:10.1107/S0907444911032835.
Kmetko, Jan, Warkentin, Matthew, Englich, Ulrich, Thorne, Robert E., E-mail: ret6@cornell.edu, and Kenyon College, Gambier, OH 43022. Sat . "Can radiation damage to protein crystals be reduced using small-molecule compounds?". Denmark. doi:10.1107/S0907444911032835.
@article{osti_22351247,
title = {Can radiation damage to protein crystals be reduced using small-molecule compounds?},
author = {Kmetko, Jan and Warkentin, Matthew and Englich, Ulrich and Thorne, Robert E., E-mail: ret6@cornell.edu and Kenyon College, Gambier, OH 43022},
abstractNote = {Free-radical scavengers that are known to be effective protectors of proteins in solution are found to increase global radiation damage to protein crystals. Protective mechanisms may become deleterious in the protein-dense environment of a crystal. Recent studies have defined a data-collection protocol and a metric that provide a robust measure of global radiation damage to protein crystals. Using this protocol and metric, 19 small-molecule compounds (introduced either by cocrystallization or soaking) were evaluated for their ability to protect lysozyme crystals from radiation damage. The compounds were selected based upon their ability to interact with radiolytic products (e.g. hydrated electrons, hydrogen, hydroxyl and perhydroxyl radicals) and/or their efficacy in protecting biological molecules from radiation damage in dilute aqueous solutions. At room temperature, 12 compounds had no effect and six had a sensitizing effect on global damage. Only one compound, sodium nitrate, appeared to extend crystal lifetimes, but not in all proteins and only by a factor of two or less. No compound provided protection at T = 100 K. Scavengers are ineffective in protecting protein crystals from global damage because a large fraction of primary X-ray-induced excitations are generated in and/or directly attack the protein and because the ratio of scavenger molecules to protein molecules is too small to provide appreciable competitive protection. The same reactivity that makes some scavengers effective radioprotectors in protein solutions may explain their sensitizing effect in the protein-dense environment of a crystal. A more productive focus for future efforts may be to identify and eliminate sensitizing compounds from crystallization solutions.},
doi = {10.1107/S0907444911032835},
journal = {Acta Crystallographica. Section D: Biological Crystallography},
issn = {0907-4449},
number = Pt 10,
volume = 67,
place = {Denmark},
year = {2011},
month = {10}
}