title: Nuclease digestion and mass spectrometric characterization of oligodeoxyribonucleotides containing 1,2-GpG, 1,2-ApG, and 1,3-GpXpG cisplatin intrastrand cross-links.
abstract: BACKGROUND
  The primary mode of action for cis-diamminedichloroplatinum (II), referred to as cisplatin, toward the treatment of solid malignancies is through formation of cross-links with DNA at purine sites, especially guanines.
  
  
  METHODS
  We prepared oligodeoxyribonucleotides (ODNs) containing a 1,2-GpG, 1,2-ApG, or 1,3-GpXpG cisplatin intrastrand cross-link and the corresponding ODNs modified with (15)N2-labeled cisplatin, and characterized these ODNs with electrospray ionization mass spectrometry (ESI-MS) and tandem MS (MS/MS). We also employed LC-MS/MS to characterize the digestion products of these ODNs after treatment with a cocktail of 4 enzymes (nuclease P1, phosphodiesterases I and II, and alkaline phosphatase).
  
  
  RESULTS
  1,2-GpG was released from the ODNs as a dinucleoside monophosphate or a dinucleotide. Analyses of the digestion products of ODNs containing a 1,2-GpG cross-link on the 5' or 3' terminus revealed that the dinucleotide carries a terminal 5' phosphate. On the other hand, digestion of the 1,3-GpXpG intrastrand cross-link yielded 3 dinucleoside products with 0, 1, or 2 phosphate groups.
  
  
  CONCLUSIONS
  The availability of the ODNs carrying the stable isotope-labeled lesions, MS/MS analyses of the cisplatin-modified ODNs, and the characterization of the enzymatic digestion products of these ODNs set the stage for the future LC-MS/MS quantification of the 1,2-GpG, 1,2-ApG, and 1,3-GpXpG lesions in cellular DNA.
authors.affiliation: Department of Chemistry-027, University of California, Riverside, CA 92521-0403, United States.
authors.forename: Renee T
authors.initials: RT
authors.lastname: Williams
authors.forename: Jenifer N
authors.initials: JN
authors.lastname: Nalbandian
authors.forename: Audrey
authors.initials: A
authors.lastname: Tu
authors.forename: Yinsheng
authors.initials: Y
authors.lastname: Wang
mesh_terms: D002945:Cisplatin / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry; D018736:DNA Adducts / Q000737:chemistry*; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000737:chemistry; D003851:Deoxyribonucleases / Q000378:metabolism*; D015226:Dinucleoside Phosphates / Q000737:chemistry; D006801:Humans; D015394:Molecular Structure; D009838:Oligodeoxyribonucleotides / Q000737:chemistry* / Q000378:metabolism*; D011721:Pyrenes / Q000737:chemistry*; D053719:Tandem Mass Spectrometry
chemical_list: D003432:Cross-Linking Reagents; D018736:DNA Adducts; D015226:Dinucleoside Phosphates; C579719:N-(deoxyguanosine-8-yl)-1-aminopyrene; D009838:Oligodeoxyribonucleotides; D011721:Pyrenes; C018309:guanylyl-(3'-5')-guanosine; D003851:Deoxyribonucleases; D003849:Deoxyguanosine; D002945:Cisplatin