| Assay Method Information | |
| | In Vitro Enzymatic Activity Assay on WRN Helicase |
| Description: | The core helicase motif of the WRN protein (aa N517-P1238) was produced for this assay (protein production as described above). A 45 oligonucleotide sequence called FLAP26 as described by Brosh et al., 2009, DOI: 10.1074/jbc.M111446200 (TTTTTTTTTTTTTTTTTTTTTTCCAAGTAAAACGACGGCCAGTGC; SEQ ID NO: 2) was purchased from IDT (Integrated DNA Technologies, Leuven, Belgium) and used as single strand DNA substrate. The ADP-Glo assay kit (Promega, Madison, WI) allowing the quantification of ADP produced in ATP hydrolysis reactions was used for setting up this assay.Time course experiments were first performed in order to determine the best enzymatic assay conditions (including buffer conditions, reaction time and concentrations of protein, ATP and DNA substrates). A typical reaction consists of 10 nM WRN protein, 0.2 nM FLAP26, and 300 micromolar ATP in the following assay buffer: 30 mM Tris pH7.5, 2 mM MgCl2, 0.02% BSA, 50 mM NaCl, 0.1% pluronic F127 prepared in DNAse free water. To evaluate the inhibition properties of compounds of the invention, serial dilutions were prepared in DMSO (10 half log dilutions from a 10 mM DMSO solution). 50 nanoliters of each concentration was pre-incubated for 3 hours in a 384 small volume assay plate (Greiner #784075) with 2.5 microliters of a 20 nM WRN helicase protein in assay buffer with 600 micromolar ATP. Control wells were included with a high control (no inhibition), containing DMSO with no test compound, and low controls (maximal inhibition), containing buffer without protein. The reaction was started by addition of 2.5 microliters of FLAP26 at 0.4 nM and incubated for 30 minutes at room temperature. The reaction was stopped with the addition of 5 microliters of the first ADP-Glo reagent and incubated for one hour to remove the excess amount of ATP. Afterwards, 10 microliters of ATP detection reagent was added and incubated for an additional hour before reading. Luminescence output was recorded using Tecan 1000 reader, with 5 minutes delay before reading. Each concentration of compound was tested in duplicates in the assay plate. |
| Affinity data for this assay | |
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