metilada

Metilada is a term used in chemistry and related fields to describe a molecule that has undergone methylation—the introduction of one or more methyl groups (CH3) to another molecule. A compound described as metilada has been modified by adding a methyl group, typically to oxygen, nitrogen, carbon, or sulfur atoms. Methylation can be achieved chemically using methylating reagents such as iodomethane (methyl iodide), dimethyl sulfate, or methyl triflate, or biologically via methyltransferase enzymes that transfer a methyl group from S-adenosyl-L-methionine to substrates. Common products include methyl esters from carboxylic acids, N-methylated amines, and O- or C-methylated phenols and heterocycles.

In biology, DNA methylation is the best-known form of metilada, involving the addition of a methyl group to cytosine residues in DNA, mainly at CpG dinucleotides. This epigenetic modification influences gene expression, genomic imprinting, and development, and aberrant methylation patterns are associated with diseases such as cancer. Methylation in proteins, lipids, and other macromolecules also modulates function and interactions.

Applications of methylated compounds span pharmaceuticals, agrochemistry, and materials science. Methylation can alter lipophilicity, metabolic stability, and receptor affinity. In environmental chemistry, methylation affects the mobility and toxicity of substances, as with methylated organics or methylated metals produced by microbial processes.

See also: methylation, DNA methylation, methyl ester, methyltransferase.