Carcinogen molecules, covalent binding

Attention has been drawn to the fact that the size and shape of the purine-pyrimidine base pair in this case is rather similar to the size and shape of the benzo[a]pyrene nucleus, which is a powerful carcinogen ( ,). That carcinogen is known to bind covalently to the N2 position of guanine (15). In the present lattice the planar purine-pyrimidine base pair rests in a position close to the guanine N2. Thus, this mode of interaction may also be a model for the interaction of planar carcinogen molecules with mA. 

PAHs are known to undergo covalent binding to macromolecules. They are potent inducers of Cyt P450. [17]. They can also be activated twice by CYP to dihydrodiol peroxides. Carcinogenicity is affected by both the number of rings and the methyl substitution, so that the toxicity pattern for the series below is as shown below [18], with toxicity increasing to the right (two separate series of molecules) ... 

Carcinogen-DNA adducts are addition products formed by covalent binding of all or part of a carcinogen molecule to chemical moieties in DNA adducts are formed when an activated chemical species (electrophilic, positively charged metabolite) binds covalently to negatively charged moieties in DNA. 

The process of initiation by genotoxic carcinogens occurs when the chemical reacts with the DNA molecule. An electrophilic (electron-seeking) compound can bind covalently to certain nucleophilic sites in DNA, forming a carcinogen-DNA adduct. Some binding sites in DNA are shown below ... 

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