Stabilization factors affecting duplex formation of peptide nucleic acid with DNA.
Peptide nucleic acid (PNA) is an oligonucleotide analogue in which the sugar-phosphate backbone is replaced by an N-(2-aminoethyl)glycine unit to which the nucleobases are attached. We investigated the thermodynamic behavior of PNA/DNA hybrid duplexes with identical nearest neighbors but with different sequences and chain lengths (5, 6, 7, 8, 10, 12, and 16 mers) to reveal whether the nearest-neighbor model is valid for the PNA/DNA duplex stability. CD spectra of 6, 7, and 8 mer PNA/DNA duplexes showed similar signal, while 10, 12, and 16 mer duplexes did not. The average difference in Delta G degrees (37) for short PNA/DNA duplexes with identical nearest-neighbor pairs was only 3.5%, whereas that of longer duplexes (10, 12, and 16 mers) was 16.4%. Therefore, the nearest-neighbor model seems to be useful at least for the short PNA/DNA duplexes. Thermodynamics of PNA/DNA duplexes containing 1--3 bulge residues were also studied. While the stability of the 12 mer DNA/DNA duplex decreased as the number of bulge bases increases, the number of bulge bases in PNA/DNA unchanged the duplex stability. Thus, the influence of bulge insertion in the PNA/DNA duplexes is different from that of a DNA/DNA duplex. This might be due to the different base geometry in a helix which may potentially make hydrogen bonds in a base pair and stacking interaction unfavorable compared with DNA/DNA duplexes.
Sugimoto
N
N
Department of Chemistry, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan. sugimoto@konan-u.ac.jp
Satoh
N
N
Yasuda
K
K
Nakano
S
S
D001482:Base Composition; D020029:Base Pairing; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D006358:Hot Temperature; D009692:Nucleic Acid Heteroduplexes / Q000737:chemistry*; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D020135:Peptide Nucleic Acids / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics
D009692:Nucleic Acid Heteroduplexes; D009838:Oligodeoxyribonucleotides; D020135:Peptide Nucleic Acids; D004247:DNA