Until recently, 5-methylcytosine (5-mC) was the only known modification of DNA for epigenetic regulation. In 2009, however, Kriaucionis1 discovered a second methylated cytosine, 5-hydroxymethylcytosine (5-hmC). The so-called 6th base, is generated by enzymatic conversion of 5-methylcytosine (5-mC) into 5-hydroxymethylcytosine by the TET family of oxygenases.
Early reports suggested that 5-hmC may represent an intermediate of active demethylation in a new pathway which demethylates DNA, converting 5-mC to cytosine. Recent evidence fuel the hypothesis that 5-hmC represents an intermediate, which could involve further oxidation of the hydroxymethyl group to a formyl or carboxyl group followed by either deformylation or decarboxylation. The carboxyl and formyl groups of 5-formylcytosine (5-fC) and 5-carboxylcytosine (5-caC) could be enzymatically removed without excision of the base.
Due to their structural similarity, these modified cytosine analogues are difficult to discriminate. The development of highly specific affinity-based reagents (such as antibodies) appears to be the most powerful way to differentially and specifically enrich 5-mC, 5-hmC & 5-fC sequences. In this context Diagenode is proud to offer a validated antibody against