(Cytosine-5)-DNA methyltransferases (C5-DNA MTases) are enzymes which catalyze meth‐ yl group transfer from S-adenosyl-L-methionine (AdoMet) to C5 atom of cytosine residue in DNA. As a result, AdoMet is converted into S-adenosyl-L-homocysteine (AdoHcy). The rec‐ ognition sites of C5-DNA MTases are usually short palindromic sequences (2–6 bp) in dou‐ ble-stranded DNA. One or both DNA strands can be methylated. The introduced methyl group is localized in the major groove of the DNA double helix and thus does not disrupt Watson–Crick interactions [1].