Linear dichroism properties and orientations of different ultraviolet transition moments of benzo[a]pyrene derivatives bound noncovalently and cova

Camille J. Roche, Nicholas Geacintov, Victor Ibanez, Ronald G. Harvey

Research output: Contribution to journalArticle

Abstract

Linear dichroism and absorption methods are used to study the orientations of transition moments of absorption bands of polycyclic aromatic epoxide derivatives which overlap with those of the DNA band in the 240-300 nm region. Both the short and long axes of the pyrene residues of 1-oxiranylpyrene (1-OP) and the (+) and (-) enantiomers of trans-7, 8-dihydroxy-anti-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE) noncovalently bound to double-stranded native DNA are oriented approximately perpendicular to the axis of the DNA helix, consistent with intercalative modes of binding. The covalent binding of these three epoxide derivatives to DNA is accompanied by reorientations of both the short and long axes of the pyrene residues. Covalent adducts derived from the highly mutagenic (+)-anti-BPDE are characterized by tilts of the short axis within 35 ° or less, and of the long axis by more than 60-80 °, with respect to the planes of the DNA bases. In the adducts derived from the binding of the less mutagenic (-)-anti-BPDE and 1-OP epoxide derivatives to DNA, the long axes of the pyrenyl rings are predominantly oriented within 25 ° of the planes of the DNA bases; however, in the case of the (-) enantiomer of BPDE, there is significant heterogeneity of conformations. In the case of the 1-OP covalent DNA adducts, the short axis of the pyrene ring system is tilted away from the planes of the DNA bases, and the pyrene ring system is not intercalated between DNA base-pairs as in the noncovalent complexes. The stereochemical properties of the saturated 7,8,9,10-ring in BPDE, or the lack of the 7 and 8 carbon atoms in 1-OP, do not seem to affect noncovalent intercalative complex formation which, most likely, is influenced mainly by the flat pyrenyl residues. These structural features, however, strongly influence the conformations of the covalent adducts, which in turn may be responsible for the differences in the mutagenic activities of these molecules.

Original languageEnglish (US)
Pages (from-to)277-288
Number of pages12
JournalBiophysical Chemistry
Volume33
Issue number3
DOIs
StatePublished - 1989

Fingerprint

Benzo(a)pyrene
pyrenes
7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide
dichroism
deoxyribonucleic acid
Derivatives
moments
DNA
Epoxy Compounds
adducts
epoxy compounds
Enantiomers
rings
enantiomers
Conformations
DNA Adducts
Electron transitions
Base Pairing
Absorption spectra
helices

Keywords

  • Benzo[a]pyrene derivative
  • Diol epoxide
  • DNA adduct
  • DNA binding
  • Linear dichroism
  • Ultraviolet transition moment

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Physical and Theoretical Chemistry

Cite this

Linear dichroism properties and orientations of different ultraviolet transition moments of benzo[a]pyrene derivatives bound noncovalently and cova. / Roche, Camille J.; Geacintov, Nicholas; Ibanez, Victor; Harvey, Ronald G.

In: Biophysical Chemistry, Vol. 33, No. 3, 1989, p. 277-288.

Research output: Contribution to journalArticle

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AU - Harvey, Ronald G.

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N2 - Linear dichroism and absorption methods are used to study the orientations of transition moments of absorption bands of polycyclic aromatic epoxide derivatives which overlap with those of the DNA band in the 240-300 nm region. Both the short and long axes of the pyrene residues of 1-oxiranylpyrene (1-OP) and the (+) and (-) enantiomers of trans-7, 8-dihydroxy-anti-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE) noncovalently bound to double-stranded native DNA are oriented approximately perpendicular to the axis of the DNA helix, consistent with intercalative modes of binding. The covalent binding of these three epoxide derivatives to DNA is accompanied by reorientations of both the short and long axes of the pyrene residues. Covalent adducts derived from the highly mutagenic (+)-anti-BPDE are characterized by tilts of the short axis within 35 ° or less, and of the long axis by more than 60-80 °, with respect to the planes of the DNA bases. In the adducts derived from the binding of the less mutagenic (-)-anti-BPDE and 1-OP epoxide derivatives to DNA, the long axes of the pyrenyl rings are predominantly oriented within 25 ° of the planes of the DNA bases; however, in the case of the (-) enantiomer of BPDE, there is significant heterogeneity of conformations. In the case of the 1-OP covalent DNA adducts, the short axis of the pyrene ring system is tilted away from the planes of the DNA bases, and the pyrene ring system is not intercalated between DNA base-pairs as in the noncovalent complexes. The stereochemical properties of the saturated 7,8,9,10-ring in BPDE, or the lack of the 7 and 8 carbon atoms in 1-OP, do not seem to affect noncovalent intercalative complex formation which, most likely, is influenced mainly by the flat pyrenyl residues. These structural features, however, strongly influence the conformations of the covalent adducts, which in turn may be responsible for the differences in the mutagenic activities of these molecules.

AB - Linear dichroism and absorption methods are used to study the orientations of transition moments of absorption bands of polycyclic aromatic epoxide derivatives which overlap with those of the DNA band in the 240-300 nm region. Both the short and long axes of the pyrene residues of 1-oxiranylpyrene (1-OP) and the (+) and (-) enantiomers of trans-7, 8-dihydroxy-anti-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE) noncovalently bound to double-stranded native DNA are oriented approximately perpendicular to the axis of the DNA helix, consistent with intercalative modes of binding. The covalent binding of these three epoxide derivatives to DNA is accompanied by reorientations of both the short and long axes of the pyrene residues. Covalent adducts derived from the highly mutagenic (+)-anti-BPDE are characterized by tilts of the short axis within 35 ° or less, and of the long axis by more than 60-80 °, with respect to the planes of the DNA bases. In the adducts derived from the binding of the less mutagenic (-)-anti-BPDE and 1-OP epoxide derivatives to DNA, the long axes of the pyrenyl rings are predominantly oriented within 25 ° of the planes of the DNA bases; however, in the case of the (-) enantiomer of BPDE, there is significant heterogeneity of conformations. In the case of the 1-OP covalent DNA adducts, the short axis of the pyrene ring system is tilted away from the planes of the DNA bases, and the pyrene ring system is not intercalated between DNA base-pairs as in the noncovalent complexes. The stereochemical properties of the saturated 7,8,9,10-ring in BPDE, or the lack of the 7 and 8 carbon atoms in 1-OP, do not seem to affect noncovalent intercalative complex formation which, most likely, is influenced mainly by the flat pyrenyl residues. These structural features, however, strongly influence the conformations of the covalent adducts, which in turn may be responsible for the differences in the mutagenic activities of these molecules.

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