Heliscreener™ WRN Helicase Unwinding Assay

The Heliscreener DNA Unwinding Assay is a biochemical assay designed to measure the DNA unwinding activity of WRN helicase (WRN-H). The assay utilizes a labeled double-stranded DNA (dsDNA) fork substrate that is quenched when intact and emits far-red fluorescence following unwinding. The assay can be performed in kinetic (continuous monitoring) or endpoint mode. Kinetic mode is recommended for initial velocity measurements, allowing for accurate enzyme kinetics and inhibitor IC50 determinations. Alternatively, for screening, the enzyme reaction can be stopped by adding the Stop & Detect Buffer B, and the quenched reactions can be read in endpoint mode. This assay is designed to be used with purified enzyme preparations. Heliscreener assays are not validated with cell lysates, blood, serum, or other biological samples.

How Does Heliscreener WRN DNA Unwinding Assay Work?
Fluorescence is quenched when the Reporter DNA is intact. WRN helicase unwinds the Reporter DNA, releasing the far-red fluorescence (Cy5) from the quencher (Iowa Black® Quencher). A Capture RNA (green) hybridizes to the fluorescent strand, preventing it from re-annealing with the quenching strand. The Heliscreener Assay is designed specifically for high-throughput screening (HTS), with a single-addition, mix-and-read format.

It is easy to integrate into automated HTS workflows, with robust detection of DNA unwinding, and compatibility with commonly used multimode plate readers. Data quality is excellent (Z’ ≥ 0.7), and the assay uses a far-red tracer to minimize interference from fluorescent compounds and light scattering.