Insight Into the Location of DNA Xenobiotic Damage by Mass Spectrometry

Abstract

Damage to DNA by a bioactivated xenobiotic typically occurs at specific sites within the genome, called hotspots. An example of this is benzo[a]-pyrene (BP), a xenobiotic that enters the body via cigarette smoking. Hotspots at which the final BP metabolite, (+/-)-anti-benzo[a]-pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE), adducts DNA oligomers have been electrochemically detected. Determination of the number of adducts formed on the DNA oligomer from exposure to the xenobiotic is necessary for further insight into the damage reaction. Analysis of the damaged DNA samples by Electrospray Ionization Mass Spectrometry (ESI-MS) allows for observation of structural features by separation of the ions present by mass. Using tandem mass spectrometry to obtain data, MS/MS spectra are interpreted for the damaged DNA and used to determine the location of the damage by observing a corresponding change in mass due to the reaction of DNA with the xenobiotic. Tandem mass spectrometry allows for the isolation of certain peaks in the spectrum to further separate and compare to similar spectra of undamaged DNA. Further collection of spectra is necessary before preliminary findings can be reported.