Analysis of platinum adducts with DNA nucleotides and nucleosides by capillary electrophoresis coupled to ESI-MS: indications of guanosine 5'-monophosphate O6-N7 chelation.
DNA is the ultimate target of platinum-based anticancer therapy. Since the N7 of guanine is known to be the major binding site of cisplatin and its analogues, adduct formation with model nucleotides, especially 2'-deoxyguanosine 5'-monophosphate (dGMP), has been studied in detail. During the last few years a coupled capillary eletrophoresis/electrospray-ionization mass spectrometry (CE/ESI-MS) method has been advantageously used in order to separate and identify platinum adducts with nucleotides in submillimolar concentrations in aqueous solutions. Beside the bisadduct, [Pt(NH(3))(2)(dNMP)(2)](2-) (NMP=2'-deoxynucleoside 5'-monophosphate), and the well-known monochloro and monohydroxo adducts, [Pt(NH(3))(2)Cl(dNMP)](-) and [Pt(NH(3))(2)(dNMP)OH](-), respectively, a third kind of monoadduct species with a composition of [Pt(NH(3))(2)(dNMP)](-) can be separated by CE and detected through the m/z values measured with ESI-MS. Different experimental setups indicate the existence of an O(6)-N7 chelate, whereas the formation of N7-alphaPO(4) macrochelates or dinuclear species is unlikely. Additionally, offline MS experiments with 2'-deoxyguanosine (dG) and stabilization of the controversially discussed O(6)-N7 chelate by oxidation with hydrogen peroxide support the assumption of the existence of O(6)-N7 chelation.
Warnke
Ulrich
U
Institute of Pharmacy, Department of Clinical Pharmacy, Freie Universität Berlin, Germany.
Rappel
Christina
C
Meier
Heiko
H
Kloft
Charlotte
C
Galanski
Markus
M
Hartinger
Christian G
CG
Keppler
Bernhard K
BK
Jaehde
Ulrich
U
D002945:Cisplatin / Q000737:chemistry*; D018736:DNA Adducts / Q000032:analysis / Q000737:chemistry*; D003848:Deoxyguanine Nucleotides / Q000737:chemistry; D019075:Electrophoresis, Capillary / Q000379:methods; D006157:Guanosine Monophosphate / Q000737:chemistry*; D007291:Inosine Monophosphate / Q000031:analogs & derivatives* / Q000737:chemistry; D015394:Molecular Structure; D009705:Nucleosides / Q000737:chemistry*; D009711:Nucleotides / Q000737:chemistry*; D009944:Organoplatinum Compounds / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods
D018736:DNA Adducts; D003848:Deoxyguanine Nucleotides; D009705:Nucleosides; D009711:Nucleotides; D009944:Organoplatinum Compounds; D007291:Inosine Monophosphate; C017193:deoxyinosine monophosphate; C007257:2'-deoxyguanosine 5'-phosphate; D006157:Guanosine Monophosphate; D002945:Cisplatin