Afmyndun

Afmyndun is the process of removing a methyl group (−CH3) from a molecule. The term is used in chemistry and biochemistry to describe reactions or enzymatic steps that shed a methyl substituent from heteroatoms such as oxygen or nitrogen, or from carbon centers.

In chemistry, afmyndun (dealkylation) encompasses O-demethylation and N-demethylation, among other forms. Typical examples include converting aryl methyl ethers to phenols and removing methyl groups from tertiary amines. Demethylation can be achieved by various reagents and conditions, including acid or base catalysis, oxidative systems, and specific demethylating reagents such as boron tribromide (BBr3) or hydride- or metal-catalyzed methods.

In biology, afmyndun denotes enzymatic removal of methyl groups from DNA, RNA or proteins. DNA afmyndun is a central aspect of epigenetic regulation: enzymes such as TET proteins oxidize 5-methylcytosine to 5-hydroxymethylcytosine and further oxidized forms, enabling repair processes that restore unmethylated cytosine. Histone afmyndun is carried out by demethylases, including LSD1 and JmjC-domain proteins, which remove methyl marks from lysine residues and influence chromatin structure and transcription.

Significance includes gene regulation, developmental processes, and disease, as well as applications in medicinal chemistry and drug development. Demethylation pathways are targets for epigenetic therapies and for understanding metabolism of certain xenobiotics. See also demethylation, methylation, and epigenetics.