Characterizing DNA photo-oxidation reactions by high-resolution mass measurements with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

J Mass Spectrom. 2000 Mar;35(3):408-16. doi: 10.1002/(SICI)1096-9888(200003)35:3<408::AID-JMS951>3.0.CO;2-0.


High-resolution mass measurements by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry were employed to characterize laser-induced oxidation of guanine in a small synthetic deoxyoligonucleotide. The oligonucleotide was exposed to high-intensity UV radiation at 266 nm to produce modifications on the guanine base. The primary product showed a +16 Da mass shift relative to the original strand, whereas secondary products showed mass shifts of +32 and +34 Da. The mass shift of the primary product is consistent with an 8-oxoguanine modification. However, the reactivity of the primary product with hot piperidine and other secondary oxidizing agents was different from that of a synthetic oligonucleotide containing 7,8-dihydro-8-oxo-2'-deoxyguanine (8-oxoG). Based upon the results, a new reaction scheme involving the formation of an epoxide ring across the C-4 and C-5 positions by UV laser-induced oxidation is suggested. The results also illustrate the ability of MALDI to characterize chemical reactivity rapidly at the a low picomolar level.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Base Sequence
  • DNA Damage*
  • In Vitro Techniques
  • Oligodeoxyribonucleotides / chemistry
  • Oligodeoxyribonucleotides / radiation effects
  • Oxidation-Reduction
  • Photochemistry
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods*


  • Oligodeoxyribonucleotides