title: A rational approach to heavy-atom derivative screening.
abstract: Despite the development in recent times of a range of techniques for phasing macromolecules, the conventional heavy-atom derivatization method still plays a significant role in protein structure determination. However, this method has become less popular in modern high-throughput oriented crystallography, mostly owing to its trial-and-error nature, which often results in lengthy empirical searches requiring large numbers of well diffracting crystals. In addition, the phasing power of heavy-atom derivatives is often compromised by lack of isomorphism or even loss of diffraction. In order to overcome the difficulties associated with the 'classical' heavy-atom derivatization procedure, an attempt has been made to develop a rational crystal-free heavy-atom derivative-screening method and a quick-soak derivatization procedure which allows heavy-atom compound identification. The method includes three basic steps: (i) the selection of likely reactive compounds for a given protein and specific crystallization conditions based on pre-defined heavy-atom compound reactivity profiles, (ii) screening of the chosen heavy-atom compounds for their ability to form protein adducts using mass spectrometry and (iii) derivatization of crystals with selected heavy-metal compounds using the quick-soak method to maximize diffraction quality and minimize non-isomorphism. Overall, this system streamlines the process of heavy-atom compound identification and minimizes the problem of non-isomorphism in phasing.
authors.affiliation: Structural Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12441 Parklawn Drive, Rockville, Maryland 20852, USA.
authors.forename: M Gordon
authors.initials: MG
authors.lastname: Joyce
authors.forename: Sergei
authors.initials: S
authors.lastname: Radaev
authors.forename: Peter D
authors.initials: PD
authors.lastname: Sun
mesh_terms: D018360:Crystallography, X-Ray / Q000379:methods*; D013058:Mass Spectrometry; D008958:Models, Molecular; D010455:Peptides / Q000032:analysis / Q000737:chemistry; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000032:analysis / Q000737:chemistry
chemical_list: D010455:Peptides; D011506:Proteins
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