title: Triosephosphate isomerase is a common crystallization contaminant of soluble His-tagged proteins produced in Escherichia coli.
abstract: Attempts to crystallize several mammalian proteins overexpressed in Escherichia coli revealed a common contaminant, triosephosphate isomerase, a protein involved in glucose metabolism. Even with triosephosphate isomerase present in very small amounts, similarly shaped crystals appeared in the crystallization drops in a number of polyethylene glycol-containing conditions. All of the target proteins were His-tagged and their purification involved immobilized metal-affinity chromatography (IMAC), a step that was likely to lead to triosephosphate isomerase contamination. Analysis of the triosephosphate isomerase crystals led to the structure of E. coli triosephosphate isomerase at 1.85 Å resolution, which is a significant improvement over the previous structure.
authors.affiliation: Department of Biochemistry, Groupe de Recherche axé sur la Structure des Protéines, McGill University, 3649 Promenade Sir William Osler, Montréal, Québec H3G 0B1, Canada.
authors.forename: Guennadi
authors.initials: G
authors.lastname: Kozlov
authors.forename: Roohi
authors.initials: R
authors.lastname: Vinaik
authors.forename: Kalle
authors.initials: K
authors.lastname: Gehring
mesh_terms: D000818:Animals; D003460:Crystallization; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000737:chemistry*; D006801:Humans; D051379:Mice; D017433:Protein Structure, Secondary; D012995:Solubility; D014305:Triose-Phosphate Isomerase / Q000096:biosynthesis / Q000737:chemistry*
chemical_list: D029968:Escherichia coli Proteins; D014305:Triose-Phosphate Isomerase
keywords: TIM; crystallization contaminants; triosephosphate isomerase