Synthesis and hybridization properties of DNA-PNA chimeras carrying 5-bromouracil and 5-methylcytosine

The preparation of 5-bromouracil and 5-methylcytosine peptide nucleic acid (PNA) monomers is described. These PNA monomers were used for the preparati on of several DNA-PNA chimeras and their hybridization properties are descr ibed. The substitution of cytosine by 5-methylcytosine in DNA-PNA chimeras increased duplex stability while substitution of thymine by 5-bromouracil m aintained 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-m ethylcytosine and 5-bromouracil in DNA-PNA chimeras destabilized triple hel ix. (C) 2000 Elsevier Science Ltd. All rights reserved.