Spectroscopic characterizations and comparisons of the structures of the covalent adducts derived from the reactions 7,8-dihydroxy-7,8,9,10-tetrahydrobenzo(a)pyrene and 9,10,11,12-tetrahydrobenzo(e)pyrene with DNA

Journal Article · Fri Jan 01 04:00:00 EST 1982 · Carcinogenesis (N.Y.); (United States)

DOI:https://doi.org/10.1093/carcin/3.3.247· OSTI ID:5405358

Geacintov, N E ^[1]; Gagliano, A G; Ibanez, V; Harvey, R G

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1. New York Univ., New York

The conformation of covalent adducts derived from the reactions of racemic 7..beta..,8..cap alpha..-dihydroxy-9..cap alpha..,10..cap alpha..-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene (BaPDE), 9,10-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene (BaPE), and 9,10-epoxy-9,10,11,12-tetrahydrobenzo(e)pyrene (BePE) with calf thymus DNA in aqueous buffer solution (25/sup 0/C, pH 7.0) were investigated and compared by means of absorption, fluorescence and electric linear dichroism techniques. Two types of conformations are recognized. Site I is characterized by a red shift (approx.10 nm) in the absorption maximum of the pyrene nucleus, a significantly reduced fluorescence yield, and a negative electric linear dichroism signal (..delta..A); this site is presumed to involve a near-parallel (within 25/sup 0/) orientation of the planar pyrene residue with the planes of the DNA bases, and a relatively strong interaction between the ..pi.. electrons of the nucleic acid bases and the pyrene residue. In site II, there is only a small red-shift in the absorption maximum (approx.2 nm), a non-zero fluorescence yield, and a positive ..delta..A throughout the absorption region of the pyrene residue; in this conformation the pyrene residue is presumed to lie on the outside of the DNA molecule, possibly in one of the grooves. The BaPDE - DNA complex displays predominantly a site II-type conformation while the BaPE - and BePE - DNA complexes display both site I and site II adducts, with site I conformations predominating. The lack of hydroxyl groups in BaPE and BePE lead to a loss in stereospecificity in covalent adduct formation. The 7 and 8 hydroxyl groups in BaPDE appear to reduce the probability of formation of site I-type covalent adducts, and appear to be, at least in part, responsible for the enantiomeric stereospecificity in the covalent reaction between BaPDE and DNA.

• DOE Contract Number: AC02-78EV04959
• OSTI ID: 5405358
• Journal Information: Carcinogenesis (N.Y.); (United States), Journal Name: Carcinogenesis (N.Y.); (United States) Vol. 3:3; ISSN CRNGD
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ABSORPTION
ADDUCTS
ANIMALS
AROMATICS
BENZOPYRENE
BODY
CATTLE
CONDENSED AROMATICS
COVALENCE
COWS
DICHROISM
DNA
DNA ADDUCTS
DOMESTIC ANIMALS
FLUORESCENCE
HYDROCARBONS
LUMINESCENCE
LYMPHATIC SYSTEM
MAMMALS
MOLECULAR STRUCTURE
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANS
POLYCYCLIC AROMATIC HYDROCARBONS
RUMINANTS
SPECIFICITY
STRUCTURAL CHEMICAL ANALYSIS
THYMUS
VERTEBRATES