Methyliert

Methyliert is the term used for the covalent introduction of a methyl group (–CH3) into a substrate. Methylation can occur on different atoms and in different contexts, altering properties such as charge, polarity, stability and reactivity. The process can be driven by chemical reagents in the laboratory or by enzymes in living cells.

In chemistry, methylation is a common modification in organic synthesis. It can target oxygen, nitrogen or carbon atoms and is used to modify functionality, protect groups, or tune physical properties of a molecule. Typical methylating agents include methyl iodide, dimethyl sulfate and related reagents. The choice of reagent and conditions determines regioselectivity and stereochemistry.

In biology, methylation is a central form of post-synthetic modification with important regulatory roles. DNA methylation typically involves the addition of a methyl group to cytosine bases, most often at CpG sites in animals, and is carried out by DNA methyltransferases using S-adenosylmethionine as the methyl donor. DNA methylation influences gene expression, genomic imprinting and transposon silencing, and it can be dynamic during development and in response to environmental cues. Demethylation can occur through active enzymatic pathways or passive dilution during DNA replication.

RNA methylation is another widespread form of methyliert, affecting RNA stability and translation. Modifications such as N6-methyladenosine (m6A) are installed by methyltransferase complexes (e.g., METTL3/METTL14) and read by specific proteins, influencing RNA processing and function.

Overall, methyliert covers both chemical transformations used in synthesis and a set of biological regulatory mechanisms that shape molecular behavior and cellular outcomes.