This compound, 3-Deazaneplanocin A (DZNep), is primarily utilized in biochemical and epigenetic research as a potent inhibitor of S-adenosylhomocysteine hydrolase (SAHase), an enzyme involved in methylation processes. By inhibiting SAHase, it leads to the accumulation of S-adenosylhomocysteine (SAH), which disrupts the methylation of DNA, RNA, and proteins. Notably, DZNep induces proteasomal degradation of enhancer of zeste homolog 2 (EZH2), a core component of the polycomb repressive complex 2 (PRC2), thereby reducing trimethylation of histone H3 at lysine 27 (H3K27me3) and reactivating epigenetically silenced genes. This mechanism is crucial for studying epigenetic regulation and gene expression. Researchers employ it to investigate the role of methylation in various biological processes, including cancer development, viral replication, and cellular differentiation. Additionally, it has shown potential in antiviral and anticancer studies, where modulation of methylation pathways can influence disease progression, such as inhibiting growth in cancer cells and certain viruses including those affecting the respiratory and nervous systems. Its application extends to exploring therapeutic strategies targeting epigenetic mechanisms in diseases where abnormal methylation plays a key role.