Direct synthesis and characterization of site-specific adenosyl adducts derived from the binding of a 3,4-dihydroxy-1,2-epoxybenzo[c]phenanthrene stereoisomer to an 11-mer oligodeoxyribonucleotide
- New York Univ., NY (United States); and others
Site-specifically modified oligonucleotides were obtained in milligram quantities by reacting racemic 3t,4r-dihydroxy-1,2t-epoxy-1,2,3,4-tetrahydrobenzo[c]phenanthrene (B[c]PhDE-2, or anti-B[c]PhDE) with the single deoxyadenosine (dA) residue in the oligodeoxynucleotide d(CTCTCACTTCC). Enzyme digestion of the covalently modified oligonucleotides with the exonuclease spleen phosphodiesterase yielded covalently linked B[c]PhDE-N{sup 6}-deoxyadenosyl monophosphate (dAMP) adducts. Comparisons of the reverse phase HPLC retention times and CD spectra of these B[c]PhDE-N{sup 6}-deoxyadenosyl monophosphate (dAMP) adducts. Comparisons of the reverse phase HPLC retention times and CD spectra of these B[c]PhDE-3{prime}-dAMP mononucleotide adducts, with those of standards derived from the reaction of the enantiomers (+)- and (-)-anti-B[c]PhDE with 3{prime}-dAMP, show that two major oligonucleotide adducts (I and II) were obtained upon reacting racemic anti-B[c]PhDE with d(CTCTCACTTCC). In oligonucleotide adduct I, the lesion is a (+)-trans-anti-B[c]PhDE-N{sup 6}-dA residue, and in oligonucleotide adduct II it is a (-)-trans-anti-B[c]PhDE-N{sup 6}-dA residue. These assignments were further confirmed using a standard {sup 32}P postlabeling assay of B[c]PhDE-3{prime}-dAMP mononucleotide adducts obtained from the digestion of oligonucleotides I and II by spleen phosphodiesterase. The melting points (T{sub m}) of duplexes of modified oligonucleotides I and II and their natural complementary strands are not affected significantly by the presence of the covalently bound benzo[c]phenanthrenyl residues. Opposite stereoselective resistance to enzyme digestion by the exonucleases snake venom phosphodiesterase and spleen phosphodiesterase is exhibited by the stereoisomeric (+)-trans- and (-)-trans-anti-B[c]PhDE-modified oligonucleotide adducts I and II. 58 refs., 10 figs.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG02-86ER60405
- OSTI ID:
- 502034
- Journal Information:
- Chemical Research in Toxicology, Vol. 8, Issue 3; Other Information: PBD: Apr-May 1995
- Country of Publication:
- United States
- Language:
- English
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