Weak Binding of Levamisole by the Cocaine-Binding Aptamer Does Not Interfere with an Aptamer-Based Detection Assay.

Autor:	Shoara AA; Department of Chemistry & Centre for Research on Biomolecular Interactions, York University, 4700 Keele St., Toronto, Ontario M3J 1P3, Canada., Churcher ZR; Department of Chemistry & Centre for Research on Biomolecular Interactions, York University, 4700 Keele St., Toronto, Ontario M3J 1P3, Canada., Slavkovic S; Department of Chemistry & Centre for Research on Biomolecular Interactions, York University, 4700 Keele St., Toronto, Ontario M3J 1P3, Canada., Johnson PE; Department of Chemistry & Centre for Research on Biomolecular Interactions, York University, 4700 Keele St., Toronto, Ontario M3J 1P3, Canada.
Jazyk:	angličtina
Zdroj:	ACS omega [ACS Omega] 2021 Sep 10; Vol. 6 (37), pp. 24209-24217. Date of Electronic Publication: 2021 Sep 10 (Print Publication: 2021).
DOI:	10.1021/acsomega.1c03781
Abstrakt:	Levamisole is a common and harmful adulterant of street samples of cocaine and can cause electrochemical tests for cocaine to give false negative results. To see if levamisole would interfere with aptamer-based bioassays, we analyzed the binding of levamisole to the cocaine-binding DNA aptamer. At low aptamer concentrations (0.5 to 20 μM) using isothermal titration calorimetry methods and thermal stability measurements, no binding of levamisole to the cocaine-binding aptamer was observed. At higher levamisole concentrations (500 μM), weak binding to the cocaine-binding aptamer was detected using nuclear magnetic resonance (NMR) spectroscopy chemical shift perturbations. NMR-detected titrations show that levamisole binding is competitive with cocaine binding, indicating that both ligands share a common binding site. Finally, we show that the presence of levamisole does not interfere with the photochrome aptamer switch binding assay for cocaine. We conclude that assays using low concentrations of cocaine, and consequently low concentration of levamisole as an adulterant, should be unaffected by the weak binding of levamisole. Competing Interests: The authors declare no competing financial interest. (© 2021 The Authors. Published by American Chemical Society.)
Databáze:	MEDLINE
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