Nuclease digestion and mass spectrometric characterization of oligodeoxyribonucleotides containing 1,2-GpG, 1,2-ApG, and 1,3-GpXpG cisplatin intrastrand cross-links

Williams, Renee T.; Nalbandian, Jenifer N.; Tu, Audrey; Wang, Yinsheng

doi:10.1016/j.cca.2012.12.010

Cited by 5 publications

(8 citation statements)

References 37 publications

(59 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The same peak (at 19.1 min) with identical retention and UV properties at 220 and 260 nm was obtained when either ODN-GTG or GTG was treated with cisplatin, and then digested by P1 nuclease, phosphodiesterase, and alkaline phosphatase, a protocol known to digest DNA to the corresponding 2′-deoxyribonucleosides. 12,23 The MS spectrum of this peak gave a series of three strong negative ion peaks (m/z 760 (100%); m/z 759 (80%); m/z 761 (60%)) indicative of the presence of Pt with its multiple stable isotopes ( Figure 5). The fragmentation spectrum of m/z 760 obtained by ESI-MS/MS analysis displayed two fragment ions centered at m/z 726 and 743 ( Figure 6), which is characteristic of the sequential loss of two ammonia substituents from dG and dA containing dimeric adducts containing a Pt.…”

Section: Mass Spectrometry Resultsmentioning

confidence: 99%

“…The above results are consistent with the proposed structure (dG-cisPt-dG of Figure ). Furthermore, this structure is expected to be the major product when DNA containing tandem GG or those separated by a pyrimidine (GTG) are treated with cisPt. ,, …”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, this structure is expected to be the major product when DNA containing tandem GG or those separated by a pyrimidine (GTG) are treated with cisPt. 24,12,25 ■ DISCUSSION…”

Section: ■ Resultsmentioning

confidence: 99%

“…11 Cleavage of the bond between the cisplatin moiety (cisPt) and guanine is also observed on the basis of the fragmentation pattern of Pt-DNA negative ion adducts during electrospray mass spectrometry. 12 Furthermore, electron transfer along the DNA strand, toward the site of the attachment of cisPt adduct, is expected to increase the cross section for DEA at the Pt site. 13 The damage induced by ionizing radiation results from both the direct and indirect effects.…”

Section: Introductionmentioning

confidence: 99%

“…In a polar medium, such as water, this resonance energy is lower by about 1 eV . Cleavage of the bond between the cisplatin moiety (cisPt) and guanine is also observed on the basis of the fragmentation pattern of Pt-DNA negative ion adducts during electrospray mass spectrometry . Furthermore, electron transfer along the DNA strand, toward the site of the attachment of cisPt adduct, is expected to increase the cross section for DEA at the Pt site…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Cisplatin Intrastrand Adducts Sensitize DNA to Base Damage by Hydrated Electrons

et al. 2014

View full text Add to dashboard Cite

The oligonucleotide TTTTTGTGTTT with or without a cisplatin adduct was reacted with hydrated electrons generated by ionizing radiation. Hydroxyl radicals were quenched with ethylenediaminetetraacetic acid (EDTA), and the solutions were bubbled with wet nitrogen to eliminate oxygen, a scavenger of hydrated electrons. Prior to irradiation, the structure of the initial cisplatin adduct was identified by mass spectrometry as G-cisplatin-G. Radiation damage to DNA bases was quantified by high-performance liquid chromatography (HPLC), after enzymatic digestion of the TTTTTGTGTTT-cisplatin complex to deoxyribonucleosides. The masses of the platinum adducts following digestion and separation by HPLC were measured by mass spectrometry. Our results demonstrate that hydrated electrons induce damage to thymines as well as detachment of the cisplatin moiety from both guanines in the oligonucleotide. This detachment regenerates both unmodified guanine and damaged guanine, in equimolar amounts. At 1000 Gy, a net average of 2.5 thymines and 1 guanine are damaged for each platinum lost from the oligonucleotide. Given the extensive base damage that occurs for each cisplatin adduct lost, it is clear that, prior to undergoing detachment, these adducts must catalyze several cycles of reactions of hydrated electrons with DNA bases. It is likely that a single reaction leads to the loss of the CIHR Author ManuscriptCIHR Author Manuscript CIHR Author Manuscript cisplatin adduct and the damage observed on the guanine base; however, the damage to the thymine bases must require the continued presence of the cisplatin adduct, acting as a catalyst. To our knowledge, this is the first time that platinum-DNA adducts have been shown to have catalytic activity. We propose two pathways for the interaction of hydrated electrons with TTTTTGTGTTTcisplatin: (1) the hydrated electron is initially captured by a thymine base and transferred by base to base electron hopping to the guanine site, where the cisplatin moiety detaches from the oligonucleotide via dissociative electron attachment, and (2) the hydrated electron interacts directly with the platinum-guanine adduct and induces detachment of the cisplatin moiety via dissociative electron attachment. Although the precise mechanism remains to be elucidated, our results provide important insights into the radiosensitization of DNA by cisplatin.

show abstract

Section: Mass Spectrometry Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…Furthermore, this structure is expected to be the major product when DNA containing tandem GG or those separated by a pyrimidine (GTG) are treated with cisPt. 24,12,25 ■ DISCUSSION…”

Section: ■ Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations