Purity >98%. Histones contain unstructured N-terminal residues that are the site of numerous post-translational modifications, involving acetylation, methylation, ubiquitination, and sumoylation to produce a specific gene regulatory outcome. Complementary enzymes catalyze the addition and removal of these modifications as needed. The amine oxidase domain-containing enzyme lysine-specific demethylase 1 (LSD1) is a member of one of two classes of histone demethylases capable of demethylating lysine residues. LSD1 shares similar catalytic sites with monoamine oxidases (MAO) A and B, the inhibition of which are used clinically to treat depression, anxiety, and Parkinson's disease. 2-PCPA is an irreversible, mechanism-based inhibitor of LSD1 with an IC50 value of 20.7 μM and a Ki value of 242.7 μM that effectively inhibits histone demethylation in vivo . Although not as selective, 2-PCPA also irreversibly inhibits monoamine oxidase (MAO) A and MAO B with IC50 values of 2.3 and 0.95 μM and Ki values of 101.9 and 16 μM, respectively.