Towards high-throughput identification of endocrine disrupting compounds with mass spectrometry.
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.
Bovet
Cédric
C
Department of Chemistry and Applied Biosciences, ETH Zurich, HCI E 329, 8093 Zurich, Switzerland.
Plet
Benoit
B
Ruff
Marc
M
Eiler
Sylvia
S
Granger
Florence
F
Panagiotidis
Andreas
A
Wenzel
Ryan
R
Nazabal
Alexis
A
Moras
Dino
D
Zenobi
Renato
R
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*
D052244:Endocrine Disruptors; D047628:Estrogen Receptor alpha; D008024:Ligands