The catalytic mechanism of DNMTs involves several steps. First, the enzyme binds to the target DNA. The key catalytic step is the transfer of a methyl group from S-adenosylmethionine (SAM) to the cytosine ring. This transfer is facilitated by a conserved cysteine residue in the active site of the enzyme, which forms a covalent bond with the cytosine, creating a transient intermediate. Finally, the methyl group is transferred to the DNA, and the enzyme is released.
