The molecular beacon-based helicase assay and its use in HTS. (A) A Cy5-labeled MBHA substrate based on the sequence of the HCV genome. (B) Four MBHAs performed in the absence of test compounds and four performed with a saturating concentration (50 µM) of a known HCV helicase inhibitor (primuline). (C) Reaction extents (F30/F0) for duplicate reactions performed with the same concentration (20 µM) of 125 different test compounds. (D) Average compound interference and inhibition obtained from the duplicate reactions shown in panel C. All reactions contained in 25 mM MOPS, pH 6.5, 1.25 mM MgCl2, 5 nM MBHA substrate, 2% (v/v) DMSO, 12.5 nM NS3h_1b(con1), and 1 mM ATP.