Electrochemical Assessment of Sequence Selective DNA Damage from Myoglogin and Cytochrome P450 Bioactivated Benzo[a]pyrene at TP53 Oligomers

Abstract

AbstractEnzymatic bioactivation of an otherwise non‐reactive species into a reactive one can lead to significant health problems in vivo. Bioactivation of benzo[a]pyrene (BP) produces known cancer causing agents, most notably anti‐benzo[a]pyrene‐r‐7,t‐8‐dihydrodiol‐t‐9,10‐epoxide (anti‐BPDE) that has been shown to attack DNA at specific genomic sites termed hotspots. Bioactivation of BP resulting in DNA damage at a specific hotspot codon was determined electrochemically. Gold electrodes were modified with DNA 21‐mer oligomers spanning codons 270–276 of the TP53 gene as well as myoglobin (Mb) that acted as an in vivo bioactivation enzyme mimic. The electrodes were exposed to BP and low concentrations of hydrogen peroxide to activate the enzymes to produce reactive metabolites that could in turn damage the DNA. DNA damage was assayed electrochemically using square wave voltammetry (SWV) to probe a diviologen compound of the form C12H25V2+C6H12V2+C12H25 (V2+=4,4′‐bipyridyl or viologen, C12‐Viologen) that has previously been employed to study DNA damage. DNA damage was dependent on both BP concentration and on the presence of the hotspot 273‐codon guanine. Additionally, cytochrome P450 1A1 and 1A2 isoforms in bicistronic membrane fractions were utilized, and DNA damage from BP exposure followed predicted patterns based on the isoform employed.