title: Conformations of adducts and kinetics of binding to DNA of the optically pure enantiomers of anti-benzo(a)pyrene diol epoxide.
abstract: Kinetic flow dichroism studies indicate that the (+) enantiomer of 7 beta, 8 alpha-dihydroxy-9 alpha, 10 alpha-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene physically bound at intercalative-type sites in double-stranded DNA undergoes covalent binding reactions to form adducts at external binding sites. The conformation of the non-covalent complex derived from the (-) stereoisomer is also intercalative in nature, but the conformations of the covalent adducts are heterogeneous and are characterized by both intercalative-type and external conformations. It is suggested that the distinctly higher biological activity of the (+) enantiomer relative to the activity of the (-) enantiomer may be related to the preponderance of 7,8,9-triol benzo(a)pyrene residues covalently linked to deoxyguanine and located at external binding sites in the DNA adducts.
mesh_terms: D015123:7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide; D000818:Animals; D001580:Benzopyrenes / Q000378:metabolism*; D001665:Binding Sites; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D004247:DNA / Q000378:metabolism*; D007700:Kinetics; D008968:Molecular Conformation; D013057:Spectrum Analysis / Q000379:methods; D013237:Stereoisomerism; D013950:Thymus Gland / Q000378:metabolism
chemical_list: D001580:Benzopyrenes; D015123:7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide; D004247:DNA