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The links between polycyclic aromatic hydrocarbon (PAH) carcinogen structures are of great interest to chemists and biologists. Benzo(a)pyrene (BP) is a PAH compound, and both (+)- and (-)-anti-BPDE undergo a chemical reaction with DNA by binding mainly to exocyclic amino groups. The conformations of four (BP)dG lesions located opposite dC at the 11-mer DNA duplex level, have been determined, using NMR techniques.

The solution conformation of the covalent (+)-trans-anti-(BP)dG adduct is reported, located opposite dC at the junctional site in the 13/10-mer DNA sequence. 13-mer acts as a template strand, incorporating the junction (BP)dG4 lesion. Intramolelcular and intermolecular proton-proton distances were defined by lower and upper bounds determined from NOESY spectra.

High-resolution 1H NMR spectroscopy of the S(61,2) and S(61,3) adducts in an oligodeoxynucleotide possessing the human N-ras codon 61 indicates that the isomers are oriented in a direction opposite to that of the styrene ring in the major grove. The styrene ring is oriented in the 3'-direction in the S adducts. The S adducts exhibit a strong sequence effect. Two conformations of the S(61,2) adduct exist in equilibrium but the S(61,3) adduct has a single conformation.

A study using NMR examination of oligodeoxynucleotides of the human n-ras protooncogene was conducted to determine the oncogenic properties of styrene oxide, a by-product of plastics and resin manufacturing. The results show that styrene oxide forms adducts at codon 61 of the human n-ras, leading to protooncogene activation, which is an early stage of carcinogenesis.