STRUCTURAL CHARACTERIZATION OF PNA-DNA DUPLEXES BY NMR - EVIDENCE FOR DNA IN A B-LIKE CONFORMATION

The nucleic acid analogues PNA (peptide nucleic acids) hybridize with DNA of complementary sequence. The solution structures of two PNA-DNA duplexes, H-(GCTATGTC)-NH2.d(GACATAGC) and H-(GTAGATCACT)-NH2.d(AGTGATCTAC), have been studied by H-1 NMR. It was found that the PNA-DNA hybrids are base paired by hydrogen bonds, most likely of the Watson-Crick type. From two-dimensional NOESY and COSY results it is concluded that the DNA strand in the PNA-DNA complex adopts a B-like structure with the deoxyribose sugars in the C2'-endo conformation.