Fluorescence characteristics of site-specific and stereochemically distinct benzo[a]pyrene diol epoxide-DNA adducts as probes of adduct conformation

Weidong Huang, Shantu Amin, Nicholas Geacintov

Research output: Contribution to journalArticle

Abstract

Spectroscopic fluorescence quenching techniques are described for distinguishing the conformational characteristics of adducts derived from the binding of the benzo[a]pyrene metabolite anti-BPDE (the diol epoxide r7,t8-dihydroxy-t9,10epoxy-7,8,9,10-tetrahydrobenz[a]pyrene) to the exocyclic amino groups of guanine ([BP]-N2-dG) and adenine ([BP]-N6-dA) in double stranded oligonucleotides. These methods are calibrated by comparing the fluorescence quenching and UV absorbance characteristics of different, stereoisomeric anti-[BP]-N2-dG adducts of known adduct conformations, previously established by high-resolution NMR techniques. It is shown that intercalative adduct conformations can be distinguished from solvent-exposed adduct conformations, e.g., adducts in which the pyrenyl residues are positioned in the minor groove. These low resolution fluorescence methods are at least 4 orders of magnitude more sensitive than the high-resolution NMR techniques; the fluorescence methods are useful for distinguishing adduct conformations when either small amounts of material are available or the NMR signals are of such poor quality that high-resolution structures cannot be determined. This methodology is illustrated using a variety of anti-BPDE-modified oligonucleotides of varying adduct conformations. It is shown that the 10S (+)-trans-anti-[BP]-N6-dA adduct in an oligonucleotide duplex containing an N-ras protooncogene sequence, believed to be conformationally heterogeneous and disordered, is significantly more exposed to the solvent environment than the stereoisomeric, intercalated 10R adduct [Zegar et al. (1996) Biochemistry 35, 6212]. These differences suggest an explanation for the greater efficiencies of excision of the 10S adduct (relative to the 10R adduct) by human nucleotide excision repair enzymes [Buterin et al. (2000) Cancer Res. 60, 1849].

Original languageEnglish (US)
Pages (from-to)118-126
Number of pages9
JournalChemical Research in Toxicology
Volume15
Issue number2
DOIs
StatePublished - 2002

Fingerprint

DNA Adducts
Benzo(a)pyrene
Epoxy Compounds
Conformations
Fluorescence
7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide
Oligonucleotides
Nuclear magnetic resonance
Quenching
Guanine
Adenine
Biochemistry
DNA Repair
Metabolites
Repair
Nucleotides
Enzymes
Neoplasms

ASJC Scopus subject areas

  • Drug Discovery
  • Organic Chemistry
  • Chemistry(all)
  • Toxicology
  • Health, Toxicology and Mutagenesis

Cite this

@article{2a31b925aaae4984ba11bf76dc4d5f61,
title = "Fluorescence characteristics of site-specific and stereochemically distinct benzo[a]pyrene diol epoxide-DNA adducts as probes of adduct conformation",
abstract = "Spectroscopic fluorescence quenching techniques are described for distinguishing the conformational characteristics of adducts derived from the binding of the benzo[a]pyrene metabolite anti-BPDE (the diol epoxide r7,t8-dihydroxy-t9,10epoxy-7,8,9,10-tetrahydrobenz[a]pyrene) to the exocyclic amino groups of guanine ([BP]-N2-dG) and adenine ([BP]-N6-dA) in double stranded oligonucleotides. These methods are calibrated by comparing the fluorescence quenching and UV absorbance characteristics of different, stereoisomeric anti-[BP]-N2-dG adducts of known adduct conformations, previously established by high-resolution NMR techniques. It is shown that intercalative adduct conformations can be distinguished from solvent-exposed adduct conformations, e.g., adducts in which the pyrenyl residues are positioned in the minor groove. These low resolution fluorescence methods are at least 4 orders of magnitude more sensitive than the high-resolution NMR techniques; the fluorescence methods are useful for distinguishing adduct conformations when either small amounts of material are available or the NMR signals are of such poor quality that high-resolution structures cannot be determined. This methodology is illustrated using a variety of anti-BPDE-modified oligonucleotides of varying adduct conformations. It is shown that the 10S (+)-trans-anti-[BP]-N6-dA adduct in an oligonucleotide duplex containing an N-ras protooncogene sequence, believed to be conformationally heterogeneous and disordered, is significantly more exposed to the solvent environment than the stereoisomeric, intercalated 10R adduct [Zegar et al. (1996) Biochemistry 35, 6212]. These differences suggest an explanation for the greater efficiencies of excision of the 10S adduct (relative to the 10R adduct) by human nucleotide excision repair enzymes [Buterin et al. (2000) Cancer Res. 60, 1849].",
author = "Weidong Huang and Shantu Amin and Nicholas Geacintov",
year = "2002",
doi = "10.1021/tx010135y",
language = "English (US)",
volume = "15",
pages = "118--126",
journal = "Chemical Research in Toxicology",
issn = "0893-228X",
publisher = "American Chemical Society",
number = "2",

}

TY - JOUR

T1 - Fluorescence characteristics of site-specific and stereochemically distinct benzo[a]pyrene diol epoxide-DNA adducts as probes of adduct conformation

AU - Huang, Weidong

AU - Amin, Shantu

AU - Geacintov, Nicholas

PY - 2002

Y1 - 2002

N2 - Spectroscopic fluorescence quenching techniques are described for distinguishing the conformational characteristics of adducts derived from the binding of the benzo[a]pyrene metabolite anti-BPDE (the diol epoxide r7,t8-dihydroxy-t9,10epoxy-7,8,9,10-tetrahydrobenz[a]pyrene) to the exocyclic amino groups of guanine ([BP]-N2-dG) and adenine ([BP]-N6-dA) in double stranded oligonucleotides. These methods are calibrated by comparing the fluorescence quenching and UV absorbance characteristics of different, stereoisomeric anti-[BP]-N2-dG adducts of known adduct conformations, previously established by high-resolution NMR techniques. It is shown that intercalative adduct conformations can be distinguished from solvent-exposed adduct conformations, e.g., adducts in which the pyrenyl residues are positioned in the minor groove. These low resolution fluorescence methods are at least 4 orders of magnitude more sensitive than the high-resolution NMR techniques; the fluorescence methods are useful for distinguishing adduct conformations when either small amounts of material are available or the NMR signals are of such poor quality that high-resolution structures cannot be determined. This methodology is illustrated using a variety of anti-BPDE-modified oligonucleotides of varying adduct conformations. It is shown that the 10S (+)-trans-anti-[BP]-N6-dA adduct in an oligonucleotide duplex containing an N-ras protooncogene sequence, believed to be conformationally heterogeneous and disordered, is significantly more exposed to the solvent environment than the stereoisomeric, intercalated 10R adduct [Zegar et al. (1996) Biochemistry 35, 6212]. These differences suggest an explanation for the greater efficiencies of excision of the 10S adduct (relative to the 10R adduct) by human nucleotide excision repair enzymes [Buterin et al. (2000) Cancer Res. 60, 1849].

AB - Spectroscopic fluorescence quenching techniques are described for distinguishing the conformational characteristics of adducts derived from the binding of the benzo[a]pyrene metabolite anti-BPDE (the diol epoxide r7,t8-dihydroxy-t9,10epoxy-7,8,9,10-tetrahydrobenz[a]pyrene) to the exocyclic amino groups of guanine ([BP]-N2-dG) and adenine ([BP]-N6-dA) in double stranded oligonucleotides. These methods are calibrated by comparing the fluorescence quenching and UV absorbance characteristics of different, stereoisomeric anti-[BP]-N2-dG adducts of known adduct conformations, previously established by high-resolution NMR techniques. It is shown that intercalative adduct conformations can be distinguished from solvent-exposed adduct conformations, e.g., adducts in which the pyrenyl residues are positioned in the minor groove. These low resolution fluorescence methods are at least 4 orders of magnitude more sensitive than the high-resolution NMR techniques; the fluorescence methods are useful for distinguishing adduct conformations when either small amounts of material are available or the NMR signals are of such poor quality that high-resolution structures cannot be determined. This methodology is illustrated using a variety of anti-BPDE-modified oligonucleotides of varying adduct conformations. It is shown that the 10S (+)-trans-anti-[BP]-N6-dA adduct in an oligonucleotide duplex containing an N-ras protooncogene sequence, believed to be conformationally heterogeneous and disordered, is significantly more exposed to the solvent environment than the stereoisomeric, intercalated 10R adduct [Zegar et al. (1996) Biochemistry 35, 6212]. These differences suggest an explanation for the greater efficiencies of excision of the 10S adduct (relative to the 10R adduct) by human nucleotide excision repair enzymes [Buterin et al. (2000) Cancer Res. 60, 1849].

UR - http://www.scopus.com/inward/record.url?scp=0036167911&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0036167911&partnerID=8YFLogxK

U2 - 10.1021/tx010135y

DO - 10.1021/tx010135y

M3 - Article

VL - 15

SP - 118

EP - 126

JO - Chemical Research in Toxicology

JF - Chemical Research in Toxicology

SN - 0893-228X

IS - 2

ER -