title: Towards high-throughput identification of endocrine disrupting compounds with mass spectrometry.
abstract: High-mass matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) combined with chemical cross-linking has the ability to monitor the ligand-dependent dimerization of the human estrogen receptor alpha ligand binding domain (hERalpha LBD) in solution. Because only ER ligands enhance the homodimer abundance, we evaluated the ability of this label-free approach for identifying endocrine disrupting compounds (EDCs) in a high-throughput manner. This was achieved by combining an automated liquid handler with an automated MS acquisition procedure, which allowed a five-fold gain in operator time compared to a fully manual approach. To detect ligand binding with enough confidence, the receptor has to be incubated with at least a 10 microM concentration of the test compound. Based on the increase of the measured homodimer intensity, eight compounds with a relative binding affinity (RBA, relative to the natural hormone estradiol) >7% were identified as ER ligands among the 28 chemicals tested. Two other compounds, quercetin and 4-tert-amylphenol, were also identified as ER ligands, although their RBAs have been reported to be only 0.01% and 0.000055%, respectively. This suggests that these two ligands have a higher affinity for hERalpha LBD than reported in the literature. The high-mass MALDI approach thus allows identifying high affinity EDCs in an efficient way.
authors.affiliation: Department of Chemistry and Applied Biosciences, ETH Zurich, HCI E 329, 8093 Zurich, Switzerland.
authors.forename: Cédric
authors.initials: C
authors.lastname: Bovet
authors.forename: Benoit
authors.initials: B
authors.lastname: Plet
authors.forename: Marc
authors.initials: M
authors.lastname: Ruff
authors.forename: Sylvia
authors.initials: S
authors.lastname: Eiler
authors.forename: Florence
authors.initials: F
authors.lastname: Granger
authors.forename: Andreas
authors.initials: A
authors.lastname: Panagiotidis
authors.forename: Ryan
authors.initials: R
authors.lastname: Wenzel
authors.forename: Alexis
authors.initials: A
authors.lastname: Nazabal
authors.forename: Dino
authors.initials: D
authors.lastname: Moras
authors.forename: Renato
authors.initials: R
authors.lastname: Zenobi
mesh_terms: D001665:Binding Sites; D019281:Dimerization; D052244:Endocrine Disruptors / Q000494:pharmacology*; D047628:Estrogen Receptor alpha / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008024:Ligands; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D052244:Endocrine Disruptors; D047628:Estrogen Receptor alpha; D008024:Ligands