title: Irregularities in enzyme assays: The case of macrophage migration inhibitory factor.
abstract: Inhibitors of human macrophage migration inhibitory factor (MIF) previously reported in the literature have been reexamined by synthesis, assaying for tautomerase activity, and protein crystallography. Substantial inconsistencies between prior and current assay results are noted. They appear to arise from difficulties with the tautomerase substrates, solubility issues, and especially covalent inhibition. Incubation time variation shows that 3, 4, 6, and 9 are covalent or slow-binding inhibitors. Two protein crystal structures are provided; one confirms that the twice-discovered 3 is a covalent inhibitor.
authors.affiliation: Department of Chemistry, Yale University, New Haven, CT 06520-8107, United States.
authors.forename: José A
authors.initials: JA
authors.lastname: Cisneros
authors.affiliation: Department of Chemistry, Yale University, New Haven, CT 06520-8107, United States.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Robertson
authors.affiliation: Department of Chemistry, Yale University, New Haven, CT 06520-8107, United States.
authors.forename: Margarita
authors.initials: M
authors.lastname: Valhondo
authors.affiliation: Department of Chemistry, Yale University, New Haven, CT 06520-8107, United States. Electronic address: william.jorgensen@yale.edu.
authors.forename: William L
authors.initials: WL
authors.lastname: Jorgensen
mesh_terms: D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D019746:Intramolecular Oxidoreductases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008263:Macrophage Migration-Inhibitory Factors / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008958:Models, Molecular; D015394:Molecular Structure; D013329:Structure-Activity Relationship
chemical_list: D004791:Enzyme Inhibitors; D008263:Macrophage Migration-Inhibitory Factors; D019746:Intramolecular Oxidoreductases; C515598:MIF protein, human
keywords: MIF; Protein crystallography; Reproducibility; Tautomerase assay