High throughput measurement of DNA base lesion repair capacity

A screening assay to identify one or more compounds from a plurality of compounds as an inhibitor of DNA repair mechanism or not an inhibitor of DNA repair mechanism, the screening assay comprising the steps of:

• a) incubating
• i) a control reaction containing a damaged DNA comprising:
• a marker attached to a first strand of the damaged DNA and
• a quencher attached to a second strand of the damaged DNA, wherein the quencher inhibits the release of a detectable signal from the marker when the damaged DNA is in double-stranded form, and the test solution in the absence of any of the plurality of compounds, and
• ii) a plurality of test reactions, each test reaction containing the damaged DNA, the test solution, and one of the plurality of compounds;
• under conditions allowing the constituents of the test solution to repair the damaged DNA such that the repaired DNA is double-stranded and the quencher inhibits the release of a detectable signal from the marker on the repaired DNA;
• b) detecting a signal emitted from the marker released from the damaged DNA if the damaged DNA is not repaired;
• c) measuring the amount of damaged DNA remaining not repaired in the control reaction and each of the plurality of test reactions;
• and
• d) identifying each compound in the plurality of compounds as:
• i) the inhibitor of DNA repair mechanism if the amount of damaged DNA remaining not repaired in the control reaction after the incubation of step a) is lower than the amount of damaged DNA remaining not repaired in the test reaction for the compound after the incubation of step a), or
• ii) not the inhibitor of DNA repair mechanism if the amount of damaged DNA remaining not repaired in the control reaction after the incubation of step a) is not lower than the amount of damaged DNA remaining not repaired in the test reaction for the compound after the incubation of step a).