6533b822fe1ef96bd127d4d7

RESEARCH PRODUCT

Spectroscopic Studies of Oligonucleotide Adducts and Base Sequence Preference of Adducts Formed by the Stereoisomers of 7,8-Dihydroxy-9,10-epoxy-7,8,9,10-Tetrahydrobenzo[a]pyrene

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Abstract 5′-d(CCTATAGATATCC) has been reacted with BPDE and the adducts derived from binding of BPDE to the exocyclic amino group of deoxyguanosine (dG) were studied with spectroscopic methods. The major dG-adducts of (+)- and (-)-anti-BPDE and a minor adduct of (+)-syn-BPDE showed the characteristics of trans-adducts. The major products formed with (+)- and (-)-syn-BPDE exhibit cis-adduct characteristics. Annealing of BPDE-modified oligonucleotides to complementary or partially complementary strands results in reduced fluorescence intensity in several cases and in others the intensity is markedly increased. These differences demonstrate that the adduct microenvironment is strongly influenced by duplex formation and interactions between the adduct and the base localized opposite the adduct. The presence of a BPDE-adduct (trans- as well as cis-adducts) strongly reduces the thermal stability of the duplexes. With the modified oligonucleotide duplex 5′-d(CCTATAGATATCC)/ 5′-d(GGATATCTATAGG), the cis-adducts o...