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Cite This: Chem. Res. Toxicol. XXXX, XXX, XXX−XXX
Interpretation of Mass Spectral Data for the Cisplatin 1,2 Intrastrand Guanine−Guanine Adduct
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option is indicated for m/z 708; and a revised caption is suggested. Arbitrarily, we chose the Pt coordination structure that others have presented.2
n important LC−MS method was reported for quantifying the cisplatin 1,2 intrastrand guanine−guanine adduct.1 We are writing to suggest some minor changes to Figure 3 of that paper. These changes have no impact on the results of the study but are anticipated to help avoid any confusion or propagation by other researchers in the field. First of all, the caption assigns peaks at 513 and 497 to ions having lost zero and one amino groups, respectively. Actually, the respective losses should be one and two amino groups. While these transitions are described correctly in the Results section, the discussion there refers to Figure 2 and data acquired by MS2, while the data for Figure 3 were acquired by MS1. Second, the term “d(GpG)” is employed to interpret a couple of the fragments, but it does not. Third, cisplatin moieties usually are depicted with ammonia rather than amide ligands on platinum.2 Fourth, m/z 708 can also be assigned in a second way, and there are peaks at m/z 530.1 and 724.1 that can be assigned. Finally, it is not necessary to depict the precursor ion as a biradical. We have repeated their Figure 3 here as Figure 1, but a different structure is presented for the precursor ion; two additional peaks are assigned (shown with boxes); a second
Poguang Wang*
Department of Pharmaceutical Sciences, Northeastern University, 360 Huntington Avenue, 206 The Fenway, Boston, Massachusetts 02115, United States
Roger W. Giese*
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Department of Pharmaceutical Sciences, Northeastern University, 360 Huntington Avenue, 206 The Fenway, Boston, Massachusetts 02115, United States
AUTHOR INFORMATION
Corresponding Authors
*E-mail:
[email protected]. *E-mail:
[email protected]. ORCID
Roger W. Giese: 0000-0003-0515-0692 Funding
This work was supported by NIEHS grant P42ES017198.
Figure 1. Full scan positive ion MS spectrum m/z 450−850 showing in source fragmentation of CP-d(GpG). Suggested assignments are as follows: m/z 497.2 [M − dR-PO3-dR − 2NH3], 513.1 [M − dR-PO3-dR − NH3]+, 530.1 [M − dR-PO3-dR ]+, 708.1 [M − dR − NH3]+, 724.1 [M − dR]+, 807.1 [M − NH3]+, and 824.0 [M]+, where dR stands for deoxyribose.
Published: October 3, 2018 © XXXX American Chemical Society
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DOI: 10.1021/acs.chemrestox.8b00134 Chem. Res. Toxicol. XXXX, XXX, XXX−XXX
Chemical Research in Toxicology
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Letters to the Editor
REFERENCES
(1) Baskerville-Abraham, I. M., Boysen, G., Troutman, J. M., Mutlu, E., Collins, L., deKrafft, K. E., Lin, W., King, C., Chaney, S. G., and Swenberg, J. A. (2009) Development of an ultra performance LC/MS method to quantify cisplatin 1,2 intrastrand guanine-guanine adducts. Chem. Res. Toxicol. 22, 905−912. (2) Sar, D. G., Montes-Bayon, M., Blanco-Gonzalez, E., and SanzMedel, A. (2010) Quantitative methods for studying DNA interactions with chemotherapeutic cisplatin. TrAC, Trends Anal. Chem. 29, 1390− 1398.
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DOI: 10.1021/acs.chemrestox.8b00134 Chem. Res. Toxicol. XXXX, XXX, XXX−XXX
