Demethylation is the chemical process resulting in the removal a methyl group (CH3) from a molecule. In biochemical systems, this process is often catalyzed by an enzyme such as one of the Cytochrome P450 (CYP) family of liver enzymes.
Proteins may also be demethylated at lysine residues, this often occurs by oxidation of the methyl substituent to a methylene, which then can be hydrolyzed from the lysine amine (now an imine) as a formaldehyde molecule.
