Determination of estrogenic activity by LYES-assay (yeast estrogen screen-assay assisted by enzymatic digestion with lyticase).
In order to enhance the sensitivity and the speed of the yeast estrogen screen (YES)-assay, which has been established in many laboratories for the determination of estrogenic activity of compounds and environmental samples, the LYES-assay, a modified version of the YES-assay including a digestion step with the enzyme lyticase, was developed. With the LYES-assay the estrogenic activities of natural (17beta-estradiol E2 and estrone), synthetic (17alpha-ethinylestradiol EE2) and pharmaceutical estrogens (diethylstilbestrol DES) as well as xenoestrogens (4-nonylphenol NP and five parabens) were determined and compared with the results obtained by other in vitro-assays namely the conventional YES-assay, the E-Screen-assay (MCF-7 breast tumor cell proliferation) and a receptor binding-assay (RB) with human estrogen receptors hER-alpha and hER-beta. In the case of E2 the LYES-assay had a significantly lower limit of quantification (LOQ) than the conventional YES-assay and even two orders of magnitude lower than the RB-assay. Compared to the E-Screen-assay the LOQ of the LYES-assay was almost one order of magnitude higher. The time required to perform the LYES-assay was as little as seven hours compared to three to five days for the conventional YES-assay. Thus, the LYES-assay is a very good alternative to existing estrogenic in vitro-assays, since it has a good sensitivity, is cheap and much faster than the other assays.
Schultis
T
T
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart, Im Bandtäle 2, 70569 Stuttgart, Germany.
Metzger
J W
JW
D001681:Biological Assay / Q000379:methods*; D004967:Estrogens / Q000032:analysis* / Q000737:chemistry; D005069:Evaluation Studies as Topic; D004693:Glucan Endo-1,3-beta-D-Glucosidase / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism*; D012680:Sensitivity and Specificity; D015003:Yeasts / Q000378:metabolism*
D004967:Estrogens; D009097:Multienzyme Complexes; C025310:lyticase; D004693:Glucan Endo-1,3-beta-D-Glucosidase; D010447:Peptide Hydrolases