title: 5,5'-Dithio-bis(2-nitrobenzoic acid) modification of cysteine improves the crystal quality of human chloride intracellular channel protein 2.
abstract: Structural studies of human chloride intracellular channel protein 2 (CLIC2) had been hampered by the problem of generating suitable crystals primarily due to the protein containing exposed cysteines. Several chemical reagents were used to react with the cysteines on CLIC2 in order to modify the redox state of the protein. We have obtained high quality crystals that diffracted to better than 2.5A at a home X-ray source by treating the protein with 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNB). After solving the crystal structure of CLIC2, we found that the DTNB had reacted with the Cys(114), and made CLIC2 in a homogenous oxidized state. This study demonstrated that the DTNB modification drastically improved the crystallization of CLIC2, and it implied that this method may be useful for other proteins containing exposed cysteines in general.
authors.affiliation: National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, No. 5 Yi Heyuan Road, Beijing 100871, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Mi
authors.forename: Lanfen
authors.initials: L
authors.lastname: Li
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Su
mesh_terms: D000595:Amino Acid Sequence; D018118:Chloride Channels / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000737:chemistry*; D004228:Dithionitrobenzoic Acid / Q000737:chemistry*; D006801:Humans; D010084:Oxidation-Reduction
chemical_list: C108828:CLIC2 protein, human; D018118:Chloride Channels; D004228:Dithionitrobenzoic Acid; D003545:Cysteine