title: DNA . RNA heteroduplex containing 8-oxo-7,8-dihydroguanosine: base pairing, structures, and thermodynamic stability.
abstract: Oligoribonucleotides containing 8-oxo-7,8-dihydroguanosine (8-oxoG) and 8-oxo-7,8-dihydro-2'-O-methylguanosine (8-oxoG-Me) were synthesized. The base pairing properties of 8-oxoG and 8-oxoG-Me in oligoribonucleotide in cDNA synthesis by reverse transcriptases were studied. dCMP was preferentially incorporated into the site opposite 8-oxoG or 8-oxoG-Me than into other dNMPs. TMP and dCMP were inserted preferentially into sites opposite 8-oxoG or 8-oxoG by reverse transcriptases. HIV-RT did not incorporate TMP, but RAV2-RT incorporated 50% more TMP than dCMP into the site opposite 8-oxoG. In the site opposite 8-oxoG-Me TMP was substantially incorporated by HIV-RT or RAV2-RT. Thermodynamic analysis of the DNA.RNA heteroduplex containing 8-oxoG revealed that 8-oxoG and 8-oxoG-Me formed base pairs with cytidine and thymidine with similar stability. The thermodynamic parameter (DeltaG degrees ) demonstrated that the formation of duplexes between 8-oxoG or 8-oxoG-Me and cytidine or thymidine is more thermodynamically favorable than with adenosine and guanosine. However, differences in the melting temperature and DeltaG degrees 's of 8-oxoG/dC and 8-oxoG/T were much smaller than between G/dC and G/T. CD spectra showed that DNA . RNA containing 8-oxoG or 8-oxoG-Me duplexes showed similarities between the A-type RNA and B-type DNA conformations.
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Kyungpook National University, Daegu 702-701, Korea.
authors.forename: Sang Kook
authors.initials: SK
authors.lastname: Kim
authors.forename: Sung Hwa
authors.initials: SH
authors.lastname: Lee
authors.forename: Oh-Shin
authors.initials: OS
authors.lastname: Kwon
authors.forename: Byung Jo
authors.initials: BJ
authors.lastname: Moon
mesh_terms: D020029:Base Pairing; D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D042822:Genomic Instability; D006151:Guanosine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000235:genetics; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D009692:Nucleic Acid Heteroduplexes / Q000737:chemistry* / Q000235:genetics; D009841:Oligonucleotides / Q000737:chemistry / Q000235:genetics; D012313:RNA / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: C116629:8-oxo-7,8-dihydro-2'-O-methylguanosine; D009692:Nucleic Acid Heteroduplexes; D009841:Oligonucleotides; D006151:Guanosine; C046215:8-hydroxyguanosine; D012313:RNA; D004247:DNA