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Lin J, Zhang J, Ma Z, Wu X, Wang F, Zhao Y, Wu K, Liu Y. Reaction of human telomeric unit TTAGGG and a photoactivatable Pt(IV) anticancer prodrug. Dalton Trans 2023; 52:12057-12066. [PMID: 37581306 DOI: 10.1039/d3dt01643a] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
The interaction of a photoactivatable diazidodihydroxido Pt(IV) prodrug, trans,trans,trans-[Pt(N3)2(OH)2(py)2] (py = pyridine; 1), with a hexamer straight human telomeric DNA unit sequence (5'-T1T2A3G4G5G6-3', I) upon light irradiation was investigated by electrospray ionization mass spectroscopy (ESI-MS). In the primary mass spectrum, two major mono-platinated I adducts with the bound Pt moieties, trans-[PtII(N3)(py)2]+ (1') and trans-[PtII(py)2]2+ (1''), respectively, were detected. It is rare to observe such high abundance and nearly equal intensity platinated DNA adducts formed by these two PtII species because 1' is usually the only major reduced Pt(II) species produced by the photodecomposition of complex 1 in the presence of DNA while 1'' was rarely detected as the major reduced PtII species reported previously. Subsequent tandem mass spectrometric analysis by collision-induced dissociation (CID) showed that in the former adduct {I + 1'}2+, G6 and A3 were the platination sites. While in the latter adduct {I + 1''}2+, a potential intrastrand crosslink was speculated after G4 and G6 sites were identified. Additionally, other minor platinated adducts like di-platinated I adduct by 1' with platination sites at G4 and G6 and mono-platinated I adducts containing base oxidation were also detected by mass spectrometry. Due to the rich guanines and their sensitivity to oxidation, the oxidation induced by 1 most probably occurred at guanine. The oxidation adducts were proposed as 8-hydroxyl guanine, spiroiminodihydantoin (Sp), 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyG), 5-guanidinohydantoin (Gh), and/or dehydroguanidinohydantoin (DGh) referring to previous reports. The obtained results provide useful chemical information about the photoreaction between photoactivatable Pt(IV) anticancer prodrugs and human telomeric DNA. Such special damages of Pt(IV) prodrugs on human telomeric DNA implicate its active role in the mechanism of Pt(IV) prodrugs and further support the unique sequence-dependent photointeraction profile of complex 1 reacting with DNA.
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Affiliation(s)
- Jiafan Lin
- Key Laboratory of Hubei Province for Coal Conversion and New Carbon Materials; School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan 430081, P. R. China.
- Beijing National Laboratory for Molecular Sciences; National Centre for Mass Spectrometry in Beijing; CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China.
| | - Jishuai Zhang
- Key Laboratory of Hubei Province for Coal Conversion and New Carbon Materials; School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan 430081, P. R. China.
- Beijing National Laboratory for Molecular Sciences; National Centre for Mass Spectrometry in Beijing; CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China.
| | - Ziqi Ma
- Key Laboratory of Hubei Province for Coal Conversion and New Carbon Materials; School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan 430081, P. R. China.
| | - Xiaoqin Wu
- Key Laboratory of Hubei Province for Coal Conversion and New Carbon Materials; School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan 430081, P. R. China.
| | - Fuyi Wang
- Beijing National Laboratory for Molecular Sciences; National Centre for Mass Spectrometry in Beijing; CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China.
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Yao Zhao
- Beijing National Laboratory for Molecular Sciences; National Centre for Mass Spectrometry in Beijing; CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China.
| | - Kui Wu
- Key Laboratory of Hubei Province for Coal Conversion and New Carbon Materials; School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan 430081, P. R. China.
| | - Yi Liu
- Key Laboratory of Hubei Province for Coal Conversion and New Carbon Materials; School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan 430081, P. R. China.
- School of Chemical and Environmental Engineering, Wuhan Polytechnic University, Wuhan 430023, P. R. China
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Kenderdine T, Fabris D. The multifaceted roles of mass spectrometric analysis in nucleic acids drug discovery and development. MASS SPECTROMETRY REVIEWS 2023; 42:1332-1357. [PMID: 34939674 PMCID: PMC9218015 DOI: 10.1002/mas.21766] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 09/23/2021] [Accepted: 11/22/2021] [Indexed: 06/07/2023]
Abstract
The deceptively simple concepts of mass determination and fragment analysis are the basis for the application of mass spectrometry (MS) to a boundless range of analytes, including fundamental components and polymeric forms of nucleic acids (NAs). This platform affords the intrinsic ability to observe first-hand the effects of NA-active drugs on the chemical structure, composition, and conformation of their targets, which might affect their ability to interact with cognate NAs, proteins, and other biomolecules present in a natural environment. The possibility of interfacing with high-performance separation techniques represents a multiplying factor that extends these capabilities to cover complex sample mixtures obtained from organisms that were exposed to NA-active drugs. This report provides a brief overview of these capabilities in the context of the analysis of the products of NA-drug activity and NA therapeutics. The selected examples offer proof-of-principle of the applicability of this platform to all phases of the journey undertaken by any successful NA drug from laboratory to bedside, and provide the rationale for its rapid expansion outside traditional laboratory settings in support to ever growing manufacturing operations.
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Affiliation(s)
| | - Dan Fabris
- Department of Chemistry, University of Connecticut
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Santos IC, Brodbelt JS. Recent developments in the characterization of nucleic acids by liquid chromatography, capillary electrophoresis, ion mobility, and mass spectrometry (2010-2020). J Sep Sci 2021; 44:340-372. [PMID: 32974962 PMCID: PMC8378248 DOI: 10.1002/jssc.202000833] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 12/25/2022]
Abstract
The development of new strategies for the analysis of nucleic acids has gained momentum due to the increased interest in using these biomolecules as drugs or drug targets. The application of new mass spectrometry ion activation techniques and the optimization of separation methods including liquid chromatography, capillary electrophoresis, and ion mobility have allowed more detailed characterization of nucleic acids and oligonucleotide therapeutics including confirmation of sequence, localization of modifications and interaction sites, and structural analysis as well as identification of failed sequences and degradation products. This review will cover tandem mass spectrometry methods as well as the recent developments in liquid chromatography, capillary electrophoresis, and ion mobility coupled to mass spectrometry for the analysis of nucleic acids and oligonucleotides.
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Affiliation(s)
- Inês C Santos
- Department of Chemistry, University of Texas at Austin, Austin, Texas, USA
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Han Y, Guo W, Zheng W, Luo Q, Wu K, Zhao Y, Wang F. Mass spectrometric quantification of the binding ratio of metal-based anticancer complexes with protein thiols. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2019; 33:951-958. [PMID: 30812058 DOI: 10.1002/rcm.8423] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 02/19/2019] [Accepted: 02/21/2019] [Indexed: 06/09/2023]
Abstract
RATIONALE The binding ratio of metal complexes with cysteinyl thiols in proteins plays an important role in deciphering the mechanisms of action of therapeutic metal complexes, but its analysis is still a significant challenge. In this work, a quantitative mass spectrometry method is developed to determine the binding ratio of metal-based anticancer complexes with cysteines in human copper chaperone protein Atox1. METHODS A novel strategy based on a thiol-specific stable isotopic labelling reagent was developed to determine the binding ratio of metal-based anticancer complexes, namely cisplatin and organometallic ruthenium complex [(η6 -biphenyl)RuCl(en)]PF6 (en = ethylenediamine), with the cysteinyl residues of Atox1. RESULTS Both cisplatin and the ruthenium complex were reactive not only to Cys15 and/or Cys18, the copper(I) binding site of Atox1, but also to Cys44. The binding ratios of the ruthenium complex with the cysteinyl residues were much higher than those of cisplatin. However, the addition of copper(I) could markedly increase the binding ratios of cysteinyl residues of Atox1 with cisplatin, but not with the ruthenium complex. CONCLUSIONS This strategy can not only precisely determine the binding ratios of metal complexes to protein thiols, but also be helpful in distinguishing thiol-binding sites from other binding sites of metal complexes in proteins. We expect wide application of this method to the research of covalent/coordinative interactions between metal complexes and protein thiols.
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Affiliation(s)
- Yumiao Han
- Beijing National Laboratory for Molecular Sciences; National Centre for Mass Spectrometry in Beijing; CAS Research/Education Centre for Excellence in Molecular Sciences; CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Wei Guo
- Beijing National Laboratory for Molecular Sciences; National Centre for Mass Spectrometry in Beijing; CAS Research/Education Centre for Excellence in Molecular Sciences; CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Wei Zheng
- Beijing National Laboratory for Molecular Sciences; National Centre for Mass Spectrometry in Beijing; CAS Research/Education Centre for Excellence in Molecular Sciences; CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Qun Luo
- Beijing National Laboratory for Molecular Sciences; National Centre for Mass Spectrometry in Beijing; CAS Research/Education Centre for Excellence in Molecular Sciences; CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Kui Wu
- Beijing National Laboratory for Molecular Sciences; National Centre for Mass Spectrometry in Beijing; CAS Research/Education Centre for Excellence in Molecular Sciences; CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Yao Zhao
- Beijing National Laboratory for Molecular Sciences; National Centre for Mass Spectrometry in Beijing; CAS Research/Education Centre for Excellence in Molecular Sciences; CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Fuyi Wang
- Beijing National Laboratory for Molecular Sciences; National Centre for Mass Spectrometry in Beijing; CAS Research/Education Centre for Excellence in Molecular Sciences; CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
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Cheng Y, Zeng W, Cheng Y, Zhang J, Zou T, Wu K, Wang F. Selective binding of an organoruthenium complex to G-rich human telomeric sequence by tandem mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2018; 32:2152-2158. [PMID: 30252980 DOI: 10.1002/rcm.8292] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Revised: 09/20/2018] [Accepted: 09/21/2018] [Indexed: 06/08/2023]
Abstract
RATIONALE Human telomeric DNA is reported to be a potential target for anticancer organometallic ruthenium(II) complexes, however, the interaction sites were not clearly discriminated and identified. METHODS In the current study, tandem mass spectrometry (MS/MS) using collision-induced dissociation (CID) was firstly introduced to identify the interaction sites of an organometallic ruthenium(II) complex [(η6 -biphenyl)Ru(en)Cl][PF6 ] (1; en = ethylenediamine) with 5'-T1 T2 A3 G4 G5 G6 -3' (I), the repeating unit of human telomeric DNA, in both positive- and negative-ion mode at a low reaction molar ratio (1/I = 0.2) which was applied to preserve the site selectivity. RESULTS Mass spectrometric results showed that mono-ruthenated I was the main product under the conditions. In positive-ion mode, MS/MS results indicated that ruthenium complex 1 binds to T2 or G6 in strand I. However, in negative-ion mode, no efficient information was obtained for exact identification of ruthenation sites which may be attributed to losses of fragment ions due to charge neutralization by the coordination of the positively charged ruthenium complex to the short MS/MS fragments. CONCLUSIONS This is the first report of using top-down MS to characterize the interactions of organometallic ruthenium(II) complexes and human telomeric DNA. Thymine can be thermodynamically competitive with guanine for binding to ruthenium complexes even at low reaction molar ratio, which inspired us to explore in greater depth the significance of thymine binding.
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Affiliation(s)
- Yiyu Cheng
- School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan, 430081, PR China
| | - Wenjuan Zeng
- Beijing National Laboratory for Molecular Sciences; National Centre for Mass Spectrometry in Beijing; CAS Key Laboratory of Analytical Chemistry for Living Biosystems, CAS Research/Education Centre for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, PR China
- University of Chinese Academy Sciences, Beijing, 100049, PR China
| | - Yang Cheng
- School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan, 430081, PR China
| | - Jishuai Zhang
- School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan, 430081, PR China
| | - Tao Zou
- School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan, 430081, PR China
| | - Kui Wu
- School of Chemistry and Chemical Engineering, Wuhan University of Science and Technology, Wuhan, 430081, PR China
| | - Fuyi Wang
- Beijing National Laboratory for Molecular Sciences; National Centre for Mass Spectrometry in Beijing; CAS Key Laboratory of Analytical Chemistry for Living Biosystems, CAS Research/Education Centre for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, PR China
- University of Chinese Academy Sciences, Beijing, 100049, PR China
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Mass spectrometry as a powerful tool to study therapeutic metallodrugs speciation mechanisms: Current frontiers and perspectives. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2017.02.012] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Schürch S. Characterization of nucleic acids by tandem mass spectrometry - The second decade (2004-2013): From DNA to RNA and modified sequences. MASS SPECTROMETRY REVIEWS 2016; 35:483-523. [PMID: 25288464 DOI: 10.1002/mas.21442] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 05/04/2014] [Accepted: 05/04/2014] [Indexed: 06/03/2023]
Abstract
Nucleic acids play key roles in the storage and processing of genetic information, as well as in the regulation of cellular processes. Consequently, they represent attractive targets for drugs against gene-related diseases. On the other hand, synthetic oligonucleotide analogues have found application as chemotherapeutic agents targeting cellular DNA and RNA. The development of effective nucleic acid-based chemotherapeutic strategies requires adequate analytical techniques capable of providing detailed information about the nucleotide sequences, the presence of structural modifications, the formation of higher-order structures, as well as the interaction of nucleic acids with other cellular components and chemotherapeutic agents. Due to the impressive technical and methodological developments of the past years, tandem mass spectrometry has evolved to one of the most powerful tools supporting research related to nucleic acids. This review covers the literature of the past decade devoted to the tandem mass spectrometric investigation of nucleic acids, with the main focus on the fundamental mechanistic aspects governing the gas-phase dissociation of DNA, RNA, modified oligonucleotide analogues, and their adducts with metal ions. Additionally, recent findings on the elucidation of nucleic acid higher-order structures by tandem mass spectrometry are reviewed. © 2014 Wiley Periodicals, Inc., Mass Spec Rev 35:483-523, 2016.
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Affiliation(s)
- Stefan Schürch
- Department of Chemistry and Biochemistry, University of Bern, CH-3012, Bern, Switzerland
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Xu Z, Brodbelt JS. Differentiation and distributions of DNA/cisplatin crosslinks by liquid chromatography-electrospray ionization-infrared multiphoton dissociation mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:71-79. [PMID: 24135806 PMCID: PMC3880628 DOI: 10.1007/s13361-013-0755-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2013] [Revised: 09/08/2013] [Accepted: 09/17/2013] [Indexed: 06/02/2023]
Abstract
Liquid chromatography-electrospray ionization-infrared multiphoton dissociation (IRMPD) mass spectrometry was developed to investigate the distributions of intrastrand crosslinks formed between cisplatin and two oligodeoxynucleotides (ODNs), d(A1T2G3G4G5T6A7C8C9C10A11T12) (G3-D) and its analog d(A1T2G3G4G5T6T7C8C9C10A11T12) (G3-H), which have been reported to adopt different secondary structures in solution. Based on the formation of site-specific fragment ions upon IRMPD, two isobaric crosslink products were differentiated for each ODN. The preferential formation of G3G4 and G4G5 crosslinks was determined as a function of reaction conditions, including incubation temperature and presence of metal ions. G3-D consistently exhibited a greater preference for formation of the G4G5 crosslink compared with the G3-H ODN. The ratio of G3G4:G4G5 crosslinks increased for both G3-D and G3-H at higher incubation temperatures or when metal salts were added. Comparison of the IRMPD fragmentation patterns of the unmodified ODNs and the intramolecular platinated crosslinks indicated that backbone cleavage was significantly suppressed near the crosslink.
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Silvestri C, Brodbelt JS. Tandem mass spectrometry for characterization of covalent adducts of DNA with anticancer therapeutics. MASS SPECTROMETRY REVIEWS 2013; 32:247-66. [PMID: 23150278 PMCID: PMC3578003 DOI: 10.1002/mas.21363] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 08/17/2012] [Accepted: 08/18/2012] [Indexed: 05/17/2023]
Abstract
The chemotherapeutic activities of many anticancer and antibacterial drugs arise from their interactions with nucleic acid substrates. Some of these ligands interact with DNA in a way that causes conformational changes or damage to the nucleic acid targets, ultimately altering recognition by key DNA-specific enzymes, interfering with DNA transcription or prohibiting replication, and terminating cell growth and proliferation. The design and synthesis of ligands that bind to nucleic acids remains a dynamic field in medicinal chemistry and pharmaceutical research. The quest for more selective and efficacious DNA-interactive anticancer chemotherapeutics has likewise catalyzed the need for sensitive analytical methods that can provide structural information about the nature of the resulting DNA adducts and provide insight into the mechanistic pathways of the DNA/drug interactions and the impact on the cellular processes in biological systems. This review focuses on the array of tandem mass spectrometric strategies developed and applied for characterization of covalent adducts formed between DNA and anticancer ligands.
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Affiliation(s)
- Catherine Silvestri
- Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712, USA
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Ryvolova M, Smerkova K, Chomoucka J, Hubalek J, Adam V, Kizek R. Glutathione modified CdTe quantum dots as a label for studying DNA interactions with platinum based cytostatics. Electrophoresis 2013; 34:801-8. [DOI: 10.1002/elps.201200664] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 01/16/2013] [Accepted: 01/30/2013] [Indexed: 11/06/2022]
Affiliation(s)
| | - Kristyna Smerkova
- Department of Chemistry and Biochemistry; Faculty of Agronomy, Mendel University in Brno; Brno; Czech Republic
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Wu K, Hu W, Luo Q, Li X, Xiong S, Sadler PJ, Wang F. Competitive binding sites of a ruthenium arene anticancer complex on oligonucleotides studied by mass spectrometry: ladder-sequencing versus top-down. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2013; 24:410-420. [PMID: 23404464 DOI: 10.1007/s13361-012-0539-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Revised: 10/30/2012] [Accepted: 11/15/2012] [Indexed: 06/01/2023]
Abstract
We report identification of the binding sites for an organometallic ruthenium anticancer complex [(η (6)-biphenyl)Ru(en)Cl][PF6] (1; en = ethylenediamine) on the 15-mer single-stranded oligodeoxynucleotides (ODNs), 5'-CTCTCTX7G8Y9CTTCTC-3' [X = Y = T (I); X = C and Y = A (II); X = A and Y = T (III); X = T and Y = A (IV)] by electrospray ionization mass spectrometry (ESI-MS) in conjunction with enzymatic digestion or tandem mass spectrometry (top-down MS). ESI-MS combined with enzymatic digestion (termed MS-based ladder-sequencing), is effective for identification of the thermodynamically-favored G-binding sites, but not applicable to determine the thermodynamically unstable T-binding sites because the T-bound adducts dissociate during enzymatic digestion. In contrast, top-down MS is efficient for localization of the T binding sites, but not suitable for mapping ruthenated G bases, due to the facile fragmentation of G bases from ODN backbones prior to the dissociation of the phosphodiester bonds. The combination of the two MS approaches reveals that G8 in each ODN is the preferred binding site for 1, and that the T binding sites of 1 are either T7 or T11 on I and IV, and either T6 or T11 on II and III, respectively. These findings not only demonstrate for the first time that T-bases in single-stranded oligonucleotides are kinetically competitive with guanine for such organoruthenium complexes, but also illustrate the relative merits of the combination of ladder-sequencing and top-down MS approaches to elucidate the interactions of metal anticancer complexes with DNA.
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Affiliation(s)
- Kui Wu
- Beijing National Laboratory for Molecular Sciences, Beijing Centre for Mass Spectrometry, Institute of Chemistry, Chinese Academy of Sciences, Beijing, People's Republic of China
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