Lysine-Specific Demethylase 1 (LSD1) is a histone-modifying enzyme that catalyzes lysine demethylation of histone H3. LSD1 plays an important role in regulation of gene expression, acting either as a transcription co-repressor or co-activator. The enzyme is implicated in cellular differentiation and has been considered as a potential target for drug discovery. The SensoLyte® LSD1 assay kit provides a convenient procedure for screening enzyme inhibitors and for detection of purified enzyme activity. This assay consists of two steps. In the first step, LSD1 enzyme is incubated with a methylated peptide substrate and hydrogen peroxide (H2O2) is generated. In the second step, in the presence of peroxidase, H2O2 reacts with fluorogenic substrate to produce fluorescence signal, that can be measured at excitation/emission = 530 nm/590 nm. The assay can be performed in a convenient 96-well microplate format.