Synthesis and Hybridization Properties of DNA–PNA Chimeras Carrying 5-Bromouracil and 5-Methylcytosine Original Research Article

The preparation of 5-bromouracil and 5-methylcytosine peptide nucleic acid (PNA) monomers is described. These PNA monomers were used for the preparation of several DNA–PNA chimeras and their hybridization properties are described. The substitution of cytosine by 5-methylcytosine in DNA–PNA chimeras increased duplex stability while substitution of thymine by 5-bromouracil maintained it. Moreover, binding of DNA–PNA chimeras to double-stranded DNA to form triple helices was studied. In contrast to DNA, the presence of 5-methylcytosine and 5-bromouracil in DNA–PNA chimeras destabilized triple helix.