What is "demethylase"

n. (context enzyme English) Any enzyme that catalyzes the removal of a methyl group from a compound

Demethylases are enzymes that remove methyl (CH-) groups from nucleic acids, proteins (in particular histones), and other molecules. Demethylase enzymes are important in epigenetic modification mechanisms. The demethylase proteins alter transcriptional regulation of the genome by controlling the methylation levels that occur on DNA and histones and, in turn, regulate the chromatin state at specific gene loci within organisms.