Identification of 7-carboxymethylguanine in DNA from pancreatic acinar cells exposed to azaserine.

Studies were undertaken to determine the identity of an azaserine:DNA adduct. The most probable adduct, 7-carboxymethylguanine, was synthesized. DNA isolated from pancreatic acinar cells treated in culture with [14C]azaserine was hydrolyzed under neutral conditions to liberate N-alkylated purines. The neutral hydrolysate was subjected to high-performance liquid chromatography along with the synthetic standard. One of the radioactive peaks from the treated DNA was found to cochromatograph with 7-carboxymethylguanine in three systems: reverse phase; anion exchange; and ion pair reverse phase. These results suggest that azaserine metabolism in acinar cells results in carboxymethylation of DNA, supporting previously proposed models of azaserine degradation.