A sensitive, homogeneous, and high-throughput assay for lysine-specific histone demethylases at the H3K4 site.

Histone methylation is a regulated feature of nucleosomes that can have an impact on gene expression. The methylation state of histone residues has also been found in recent years to be associated with various disorders. Tools for detecting methylation state changes are very useful for dissecting the function of these epigenetic marks. In this work, a sensitive homogeneous assay for histone demethylase activity at the H3K4 site has been developed in a time-resolved fluorescent resonance energy transfer assay format. The assay is based on the detection of the unmethylated H3 peptide by a fluorescent europium-chelate labeled monoclonal antibody binding specifically to the H3K4 site. The assay was validated for histone lysine-specific demethylase 1 and was demonstrated to be a suitable assay for inhibitor profiling and high-throughput screening.