N7-guanine in DNA (N7-G)

The N7 position of guanine in DNA is a nucleophilic site particularly susceptible to alkylation or adduct formation by various endogenous and exogenous alkylating agents. Located in the major groove of DNA, it plays a significant role in DNA damage and repair processes. Guanine, one of the four main nucleotide bases in DNA, pairs with cytosine. The N7 position is the most nucleophilic site in DNA and is frequently targeted by alkylating agents. Alkylation at this position creates a positive charge, significantly decreasing guanine's pKa. N7-guanine adducts serve as extensively studied biomarkers for exposure to carcinogens and other DNA-damaging agents. While often formed, they may have minimal direct biological relevance due to chemical instability and non-participation in Watson-Crick base pairing, but can lead to secondary, more persistent and mutagenic lesions like ring-opened FAPy adducts. They are excellent biomarkers for internal exposure to direct-acting and metabolically activated carcinogens.

Other names

N7-guanine adductsN7-alkylguanineN7-position of guanine

Site for DNA alkylation, Formation of DNA adducts