Covalent binding of isomeric benzo(a)pyrene diol-epoxides to DNA
The authors have compared the abilities of two diol-epoxide derivatives of benzo(a)pyrene (B(a)P) to bind covalently to DNA in a simple in vitro system. Purified DNA in aqueous solution was allowed to react with (+/-)-7..cap alpha..,8..beta..-dihydroxy-9..beta..,10..beta..-oxy-7,8,9,10-tetrahydroB(a)P (BPDE) or with (+/-)-9..cap alpha..,10..beta..-dihydroxy-7..cap alpha..,8..cap alpha..-oxy-7,8,9,10-tetrahydroB(a)P (reverse BPDE) to completion. After repurification of the DNA, binding was detected by fluorescence spectroscopy or by absorbance spectroscopy. Both BPDE and reverse BPDE but not their hydrolysis products exhibited binding which increased linearly with increasing diol epoxide concentration. When DNA modified by reverse BPDE was enzymatically hydrolysed, two major fluorescent deoxyribonuclioside-adducts were detected by reverse phase h.p.l.c. Absorbance and fluorescence spectroscopy of modified native DNA suggested that the pyrene nucleus of reverse BPDE but not of BPDE was intercalated in the DNA double helix. This suggestion was supported by fluorescence-quenching studies. Covalent binding of reverse BPDE to DNA was effectively blocked by low concentrations of Mg/sup 2 +/, suggesting that formation of a non-covalent intercalation complex may be a prerequisite for covalent reaction.
- Research Organization:
- Oak Ridge National Lab., TN
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 5221695
- Journal Information:
- Carcinogenesis (N.Y.); (United States), Journal Name: Carcinogenesis (N.Y.); (United States) Vol. 3:9; ISSN CRNGD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400104* -- Spectral Procedures-- (-1987)
ABSORPTION SPECTROSCOPY
ADDUCTS
AROMATICS
BENZOPYRENE
CHEMICAL BONDS
CHROMATOGRAPHY
CONDENSED AROMATICS
COVALENCE
DNA
EMISSION SPECTROSCOPY
EPOXIDES
FLUORESCENCE SPECTROSCOPY
HYDROCARBONS
LIQUID COLUMN CHROMATOGRAPHY
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
SEPARATION PROCESSES
SPECTROSCOPY