Document Type
Journal Article
Department/Unit
Department of Physics
Title
Measuring the kinetics of the binding of xenoestrogens and estrogen receptor alpha by fluorescence polarization
Language
English
Abstract
© 2014 American Chemical Society. The mechanism of endocrine disruption by environmental xenoestrogens is unclear. Bisphenol-A (BPA) is an example. Its concentration in human serum is low, and its binding with estrogen receptor (ER) is weak. Yet its effect on prostate and mammary gland development was observed. We investigated whether this effect could be explained in terms of binding kinetics. We used the method of fluorescence polarization anisotropy to measure the kinetic rate constants of the binding of ERα with 19 xenoestrogens. Relative binding affinities (RBA) were also deduced from the kinetics. We drew three observations. First, our RBAs were consistent with published values, thus establishing the validity of our results. Second, our method allowed the determination of low RBAs (∼10-4) of lipophilic ligands, such as dibutyl phthalate. They could not be measured by steady-state IC50 assays because of their low solubility. Third, we found that BPA had a surprisingly high kon > 104 M-1 s-1. While its RBA was 1500 times lower than that of 17β estradiol (E2), its kon was >1/90 that of E2. As a result, a 10 min surge of BPA from pM to nM could drive the fraction of BPA-activated ERα to a potent 0.1%. This might help to explain the observable estrogenic impacts of BPA.
Publication Date
2014
Source Publication Title
Environmental Science and Technology
Volume
48
Issue
19
Start Page
11591
End Page
11599
Publisher
American Chemical Society
DOI
10.1021/es503801c
Link to Publisher's Edition
http://dx.doi.org/10.1021/es503801c
ISSN (print)
0013936X
ISSN (electronic)
15205851
APA Citation
Yiu, K., Lee, C., Kwok, K., & Cheung, N. (2014). Measuring the kinetics of the binding of xenoestrogens and estrogen receptor alpha by fluorescence polarization. Environmental Science and Technology, 48 (19), 11591-11599. https://doi.org/10.1021/es503801c