A methylase is an enzyme that attaches a methyl group to a molecule.

These are found in prokaryotes and eukaryotes. Bacteria use methylase to differentiate between foreign genetic material and their own, thus protecting their DNA from their own immune system. By placing a methyl group on a base of the recognition site of a restriction endonuclease, methylases prevent the enzyme from cleaving the bacterial DNA. ^[1]

There are methylases that can methylate DNA, RNA, proteins, or small molecules, for example, DNA methyltransferase, which methylates cytosine residues and adenine residues in DNA.

See also: Demethylase

[edit] References

1. ^ Nelson Biology 12 (2003)

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