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Das R, Karri R, Chalana A, Rai RK, Roy G. Uncovering the Role of Methylmercury on DNA Lesions at Cytotoxic Concentrations in Glutathione-Depleted Cells: Insights from Experimental and Computational Studies. Inorg Chem 2024; 63:10455-10465. [PMID: 38743433 DOI: 10.1021/acs.inorgchem.3c04579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Organomercurials (RHg+), especially methylmercury (MeHg+) and ethylmercury (EtHg+), are considered to be more neurotoxic than the inorganic counterpart (Hg2+). They cause massive DNA damage in cells, especially in neurons, where cellular glutathione (GSH) levels are significantly low. However, the mechanism by which RHg+ exerts massive DNA damage at cytotoxic concentrations in brain cells remains obscure. In this study, we investigated the effect of RHg+ on the structural and electronic properties of nucleosides and its effects on DNA damage. The direct interaction of RHg+ with the nucleoside significantly weakens N-glycosidic bonds, decreases the C-H bond energy of sugar moieties, and increases the electrophilicity of the C8-center of purine bases. As a consequence, RHg+-conjugated DNA molecules are extremely labile and highly sensitive to any nucleophiles/radicals present in GSH-depleted cells and, thus, undergo enhanced oxidative and unusual alkylative DNA damage. We also report a functional model of organomercurial lyase, which showed excellent cytoprotective effect against RHg+-induced cytotoxicity; this reverses the activity of glutathione reductase inhibited by MeHgCl and ceases oxidative and alkylating DNA damage. This intriguing finding provides new mechanistic insight into the mode of action of organomercurials in GSH-depleted cells and their adverse effects on individuals with neurodegenerative disorders associated with oxidative stress.
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Affiliation(s)
- Ranajit Das
- Department of Chemistry, School of Natural Sciences, Shiv Nadar Institution of Eminence Deemed to be University, Dadri, UP 201314, India
| | - Ramesh Karri
- Department of Chemistry, School of Natural Sciences, Shiv Nadar Institution of Eminence Deemed to be University, Dadri, UP 201314, India
- Ruhvenile Biomedical OPC Pvt. Ltd., New Delhi 110070, Delhi, India
| | - Ashish Chalana
- Centre for Development of Biomaterials, Department of Chemistry & Biochemistry, Sharda University, Greater Noida, UP 201306, India
| | - Rakesh Kumar Rai
- Department of Chemistry, Indian Institute of Technology Tirupati, Tirupati, AP 517619, India
| | - Gouriprasanna Roy
- Department of Chemistry, Indian Institute of Technology Tirupati, Tirupati, AP 517619, India
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Kumar Rai R, Shankar Pati R, Islam A, Roy G. Detoxification of organomercurials by thiones and selones: A short review. Inorganica Chim Acta 2022. [DOI: 10.1016/j.ica.2022.120980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Nogara PA, Oliveira CS, Schmitz GL, Piquini PC, Farina M, Aschner M, Rocha JBT. Methylmercury's chemistry: From the environment to the mammalian brain. Biochim Biophys Acta Gen Subj 2019; 1863:129284. [PMID: 30659885 DOI: 10.1016/j.bbagen.2019.01.006] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 12/14/2018] [Accepted: 01/09/2019] [Indexed: 02/06/2023]
Abstract
Methylmercury is a neurotoxicant that is found in fish and rice. MeHg's toxicity is mediated by blockage of -SH and -SeH groups of proteins. However, the identification of MeHg's targets is elusive. Here we focus on the chemistry of MeHg in the abiotic and biotic environment. The toxicological chemistry of MeHg is complex in metazoans, but at the atomic level it can be explained by exchange reactions of MeHg bound to -S(e)H with another free -S(e)H group (R1S(e)-HgMe + R2-S(e)H ↔ R1S(e)H + R2-S(e)-HgMe). This reaction was first studied by professor Rabenstein and here it is referred as the "Rabenstein's Reaction". The absorption, distribution, and excretion of MeHg in the environment and in the body of animals will be dictated by Rabenstein's reactions. The affinity of MeHg by thiol and selenol groups and the exchange of MeHg by Rabenstein's Reaction (which is a diffusion controlled reaction) dictates MeHg's neurotoxicity. However, it is important to emphasize that the MeHg exchange reaction velocity with different types of thiol- and selenol-containing proteins will also depend on protein-specific structural and thermodynamical factors. New experimental approaches and detailed studies about the Rabenstein's reaction between MeHg with low molecular mass thiol (LMM-SH) molecules (cysteine, GSH, acetyl-CoA, lipoate, homocysteine) with abundant high molecular mass thiol (HMM-SH) molecules (albumin, hemoglobin) and HMM-SeH (GPxs, Selenoprotein P, TrxR1-3) are needed. The study of MeHg migration from -S(e)-Hg- bonds to free -S(e)H groups (Rabenstein's Reaction) in pure chemical systems and neural cells (with special emphasis to the LMM-SH and HMM-S(e)H molecules cited above) will be critical to developing realistic constants to be used in silico models that will predict the distribution of MeHg in humans.
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Affiliation(s)
- Pablo A Nogara
- Departamento de Bioquímica e Biologia Molecular, CCNE, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Cláudia S Oliveira
- Departamento de Bioquímica e Biologia Molecular, CCNE, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Gabriela L Schmitz
- Departamento de Bioquímica e Biologia Molecular, CCNE, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil
| | - Paulo C Piquini
- Departamento de Física, CCNE, Universidade Federal de Santa Maria (UFSM), Santa Maria, RS, Brazil
| | - Marcelo Farina
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - João B T Rocha
- Departamento de Bioquímica e Biologia Molecular, CCNE, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.
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Dairaku T, Furuita K, Sato H, Šebera J, Nakashima K, Ono A, Sychrovský V, Kojima C, Tanaka Y. HgII/AgI-mediated base pairs and their NMR spectroscopic studies. Inorganica Chim Acta 2016. [DOI: 10.1016/j.ica.2016.03.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Tanaka Y, Ono A. Nitrogen-15 NMR spectroscopy of N-metallated nucleic acids: insights into 15N NMR parameters and N–metal bonds. Dalton Trans 2008:4965-74. [DOI: 10.1039/b803510p] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Onyido I, Norris AR, Buncel E. Biomolecule--mercury interactions: modalities of DNA base--mercury binding mechanisms. Remediation strategies. Chem Rev 2005; 104:5911-29. [PMID: 15584692 DOI: 10.1021/cr030443w] [Citation(s) in RCA: 311] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ikenna Onyido
- Department of Chemistry and Center for Agrochemical Technology, University of Agriculture, Makurdi, Nigeria
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O'Connor CJ, Carlin RL. Electron paramagnetic resonance investigation of crystal field, nuclear quadrupole, and structural properties of two manganese(II) compounds. Inorg Chem 2002. [DOI: 10.1021/ic50144a015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Canty AJ, Fyfe M, Gatehouse BM. Organometallic compounds containing a guanidinium group. Phenylmercury(II) derivatives of creatine and creatinine. Inorg Chem 2002. [DOI: 10.1021/ic50184a015] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Marzilli LG, Trogler WC, Hollis DP, Kistenmacher TJ, Chang CH, Hanson BE. Nucleoside complexing. Longitudinal relaxation studies of metal binding sites in adenosine and cytidine. Inorg Chem 2002. [DOI: 10.1021/ic50152a061] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Mansy S, Tobias RS. Heavy metal-nucleotide reactions. IV. Nature of the reaction between mercury(II) and uridine or thymidine. Vibrational spectroscopic studies on binding to N(3), C(4)=O, and C(5) of the uracil base. Inorg Chem 2002. [DOI: 10.1021/ic50144a014] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Duguid JG, Bloomfield VA, Benevides JM, Thomas GJ. Raman spectroscopy of DNA-metal complexes. II. The thermal denaturation of DNA in the presence of Sr2+, Ba2+, Mg2+, Ca2+, Mn2+, Co2+, Ni2+, and Cd2+. Biophys J 1995; 69:2623-41. [PMID: 8599669 PMCID: PMC1236500 DOI: 10.1016/s0006-3495(95)80133-5] [Citation(s) in RCA: 165] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Differential scanning calorimetry, laser Raman spectroscopy, optical densitometry, and pH potentiometry have been used to investigate DNA melting profiles in the presence of the chloride salts of Ba2+, Sr2+, Mg2+, Ca2+, Mn2+, Co2+, Ni2+, and Cd2+. Metal-DNA interactions have been observed for the molar ratio [M2+]/[PO2-] = 0.6 in aqueous solutions containing 5% by weight of 160 bp mononucleosomal calf thymus DNA. All of the alkaline earth metals, plus Mn2+, elevate the melting temperature of DNA (Tm > 75.5 degrees C), whereas the transition metals Co2+, Ni2+, and Cd2+ lower Tm. Calorimetric (delta Hcal) and van't Hoff (delta HVH) enthalpies of melting range from 6.2-8.7 kcal/mol bp and 75.6-188.6 kcal/mol cooperative unit, respectively, and entropies from 17.5 to 24.7 cal/K mol bp. The average number of base pairs in a cooperative melting unit (<nmelt>) varied from 11.3 to 28.1. No dichotomy was observed between alkaline earth and transition DNA-metal complexes for any of the thermodynamic parameters other than their effects on Tm. These results complement Raman difference spectra, which reveal decreases in backbone order, base unstacking, distortion of glycosyl torsion angles, and rupture of hydrogen bonds, which occur after thermal denaturation. Raman difference spectroscopy shows that transition metals interact with the N7 atom of guanine in duplex DNA. A broader range of interaction sites with single-stranded DNA includes ionic phosphates, the N1 and N7 atoms of purines, and the N3 atom of pyrimidines. For alkaline earth metals, very little interaction was observed with duplex DNA, whereas spectra of single-stranded complexes are very similar to those of melted DNA without metal. However, difference spectra reveal some metal-specific perturbations at 1092 cm-1 (nPO2-), 1258 cm-1 (dC, dA), and 1668 cm-1 (nC==O, dNH2 dT, dG, dC). Increased spectral intensity could also be observed near 1335 cm-1 (dA, dG) for CaDNA. Optical densitometry, employed to detect DNA aggregation, reveals increased turbidity during the melting transition for all divalent DNA-metal complexes, except SrDNA and BaDNA. Turbidity was not observed for DNA in the absence of metal. A correlation was made between DNA melting, aggregation, and the ratio of Raman intensities I1335/I1374. At room temperature, DNA-metal interactions result in a pH drop of 1.2-2.2 units for alkaline earths and more than 2.5 units for transition metals. Sr2+, Ba2+, and Mg2+ cause protonated sites on the DNA to become thermally labile. These results lead to a model that describes DNA aggregation and denaturation during heating in the presence of divalent metal cations; 1) The cations initially interact with the DNA at phosphate and/or base sites, resulting in proton displacement. 2) A combination of metal-base interactions and heating disrupts the base pairing within the DNA duplex. This allows divalent metals and protons to bind to additional sites on the DNA bases during the aggregation/melting process. 3) Strands whose bases have swung open upon disruption are linked to neighboring strands by metal ion bridges. 4) Near the midpoint of the melting transition, thermal energy breaks up the aggregate. We have no evidence to indicate whether metal ion cross-bridges or direct base-base interactions rupture first. 5) Finally, all cross-links break, resulting in single-stranded DNA complexed with metal ions.
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Affiliation(s)
- J G Duguid
- Department of Biochemistry, University of Minnesota, St. Paul 55108, USA
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Tajmir-Riahi HA, Langlais M, Savoie R. A laser Raman spectroscopic study of the interaction of the methylmercury cation with AMP, ADP and ATP. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 956:211-6. [PMID: 3167070 DOI: 10.1016/0167-4838(88)90137-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The interaction of the CH3Hg+ cation with adenosine 5'-monophosphate, adenosine 5'-diphosphate, and adenosine 5'-triphosphate has been studied in aqueous solution at neutral pH by laser Raman spectroscopy. Metal binding is shown to occur preferentially at the N-1 ring position of adenine, with some indication of coordination to the N-7 site and substitution of a proton on the exocyclic NH2 group of the nucleic base. Binding of the cation to phosphate groups also occurs extensively, with both the -PO2-3 and -PO-2 groups. The equilibrium constants for the binding to the phosphate groups and for N-1 coordination are approx. 70 and 600 M-1, respectively.
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Tajmir-Riahi HA, Langlais M, Savoie R. A laser Raman spectroscopic study of the interaction of calf-thymus DNA with Cu(II) and Pb(II) ions: metal ion binding and DNA conformational changes. Nucleic Acids Res 1988; 16:751-62. [PMID: 3340554 PMCID: PMC334689 DOI: 10.1093/nar/16.2.751] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The interaction of calf-thymus DNA with Cu(II) and Pb(II) ions has been investigated in H2O and D2O solutions at physiological pH, using laser Raman spectroscopy. The results confirm the destabilizing effect of Cu2+ ions, which are shown to bind strongly to the guanine and cytidine bases, perturbing the A-T base pairs and disrupting the double-helical structure of DNA, whose conformation is markedly altered by these interactions. Earlier claims that Pb2+ ions destabilize DNA are not supported by the present study. These ions are found to interact only weakly with the nucleic bases, binding to the N7 position of the guanine bases and also interacting with the A-T pairs. Both types of ions are found to interact with the charged phosphate groups of DNA, although these sites are preferred over the nucleic bases by Pb2+ ions.
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Mikulski CM, Minutella R, De Franco N, Borges G, Karayannis NM. Adenosine adducts with first row transition metal perchlorates. Inorganica Chim Acta 1986. [DOI: 10.1016/s0020-1693(00)84309-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Stocco GC, Pellerito L, Girasolo MA, Osborne AG. Organotin(IV) derivatives of the ambidentate ligand 2-thiouracil. Infrared, Mössbauer, 1H and 13C NMR studies. Inorganica Chim Acta 1984. [DOI: 10.1016/s0020-1693(00)82513-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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18
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Tomasselli AG, Noda LH. Baker's yeast adenylate kinase. Evidence of conformational change from intrinsic fluorescence and difference spectra. Determination of the structure of enzyme-bound metal-nucleotide by use of phosphorothioate analogues of ATP. EUROPEAN JOURNAL OF BIOCHEMISTRY 1983; 132:109-15. [PMID: 6301817 DOI: 10.1111/j.1432-1033.1983.tb07333.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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19
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Organomercury(II) derivatives of 2-thiouracil. An infrared and proton magnetic resonance study of structures. Inorganica Chim Acta 1983. [DOI: 10.1016/s0020-1693(00)86489-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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15. Reactions of calf thymus DNA with the electrophiles methylmercury(ii) nitrate, cis-dichlorodiammineplatinum(ii), and trans-dichlorodiammineplatinum(ii) studied using raman difference spectroscopy. Biophys Chem 1982. [DOI: 10.1016/0301-4622(82)80006-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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21
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McConnell B, Hoo DL. 1H-NMR lifetimes of cytosine interactions with the DNA melting probe, methylmercury. Chem Biol Interact 1982; 39:351-62. [PMID: 7074711 DOI: 10.1016/0009-2797(82)90051-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Studies on monomeric cytosine were undertaken to establish a kinetic foundation for the progressive melting of DNA by the mutagen, methylmercury. The reversible displacement of protons by methylmercury at the amino group of cytosine is slow on the 1H-NMR time scale at 100 and 360 MHz. Exchange coupled resonances are produced, not only for all protons of the free- and mercurated amino species, but for the rotational isomers of the latter. These spectra provide for assignment of all exchange-coupled resonances, selection of resonances providing mercuration rates from line shape and measurement of pH-dependent reciprocal lifetimes of the free-amino species (less than or equal to 6 s-1 at pH 3 and 15 s-1 at pH 4). Evidence is presented for the existence of an amino-mercurated species of cytidine thus far not reported (formation constant, 10.
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Lönnberg H, Arpalahti J. Stability constants for some transition metal complexes of adenosine and 9-(β-D-ribofuranosyl)purine in aqueous solution. Inorganica Chim Acta 1981. [DOI: 10.1016/s0020-1693(00)90779-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Metal ion-biomolecule interactions. II. Methylmercuration of the deprotonated amino groups in adenine, guanine, and cytosine derivatives, and its relationship to amino group acidity. J Inorg Biochem 1981. [DOI: 10.1016/s0162-0134(00)80297-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Beauchamp AL. Crystal structure of ?-adeninatobis (methylmercury (II)) perchlorate monohydrate. ACTA ACUST UNITED AC 1980. [DOI: 10.1007/bf01237625] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Lanir A, Yu NT. A Raman spectroscopic study of the interaction of divalent metal ions with adenine moiety of adenosine 5'-triphosphate. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(18)50496-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Sanyal G, Khalifah RG. Kinetics of organomercurial reactions with model thiols: sensitivity to exchange of the mercurial labile ligand. Arch Biochem Biophys 1979; 196:157-64. [PMID: 507800 DOI: 10.1016/0003-9861(79)90562-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Raman spectra of methyl derivatives of 5′-adenosine monophosphate, tubercidin, inosine, uridine and cytidine. Perturbation of nucleoside vibrations by electrophilic attack at different sites. ACTA ACUST UNITED AC 1979. [DOI: 10.1016/0584-8539(79)80187-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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29
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Gruenwedel DW, Brown SE. Sedimentation and viscosity of bacteriophage T7 DNA in presence of CH3HgOH. Biopolymers 1978. [DOI: 10.1002/bip.1978.360170306] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Anderson RR, Maki AH. OPTICAL DETECTION OF MAGNETIC RESONANCE STUDIES OF THE PHOSPHORESCENT STATES OF MONONUCLEOTIDE-METHYLMERCURY(II) COMPLEXES. Photochem Photobiol 1977. [DOI: 10.1111/j.1751-1097.1977.tb09132.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Chrisman RW, Mansy S, Peresie HJ, Ranade A, Berg TA, Tobias RS. Heavy metal-nucleotide interactions. IX. Raman difference spectroscopic studies on the binding of CH3Hg(II) to 1-methylthymine, thymidine-5'-monophosphate, DNA models and native DNA. BIOINORGANIC CHEMISTRY 1977; 7:245-66. [PMID: 18215 DOI: 10.1016/s0006-3061(00)80098-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Raman spectra have been obtained for dTMP and its complex with CH3Hg (II) in aqueous solution as a function of pH. Difference spectroscopy is employed to increase the sensitivity of the Raman technique. The binding reaction is essentially quantitative from pH 3 to 9, and the value of the equilibrium constant for CH3HgOH2+ + dThd in equilibrium CH3Hg(dThdH--1) + H30+ is estimated from intensity measurements to be 0.6 in reasonable agreement with an earlier value based upon uv spectrophotometric data. Binding is to N(3) with substitution of CH3Hg+ for the proton. A similar reaction occurs with 1-MeThy. Raman spectra for aqueous and crystalline 1-MeThy and for the complex CH3Hg(1-MeThyH--1) are reported. The spectrum of crystalline Hg(1-MeThyH--1)2, for which the crystal structure is known, also was obtained for comparison. Raman difference spectroscopy was used to confirm that CH3Hg (II) binds to N(3) of dTMP and N(1) of GMP at r = 0.2 (MeHg+: phosphate) ratios with mixtures of GMP + CMP + AMP + dTMP. In contrast, native calf thymus DNA does not appear to bind CH3Hg(II) at these sites at r = 0.15, although no significant amount of free CH3HgOH is present. With r = 0.3, extensive binding occurs both to the Thy and Gua bases. Raman difference spectroscopy is a valuable technique for studying the binding of ions and molecules to polynucleotides in moderately dilute aqueous solution.
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Fu JC, Gruenwedel DW. Preferential solvation of methylmercurated calf thymus deoxyribonucleic acid. Arch Biochem Biophys 1976; 174:402-13. [PMID: 1241758 DOI: 10.1016/0003-9861(76)90368-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Beck W, Kottmair N. Neue Übergangsmetallkomplexe mit Nuclein-Basen und Nucleosiden. ACTA ACUST UNITED AC 1976. [DOI: 10.1002/cber.19761090318] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Jennette KW, Lippard SJ, Ucko DA. 13C magnetic resonance investigation of mercury (II) binding to nucleosides and thiolated nucleosides in dimethyl sulfoxide. BIOCHIMICA ET BIOPHYSICA ACTA 1975; 402:403-12. [PMID: 1164524 DOI: 10.1016/0005-2787(75)90275-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Natural abundance, proton-decoupled 13C magnetic resonance spectroscopy is shown to be a useful technique for identifying the mercury (II) binding sites on nucleosides and especially thiolated nucleosides. Measurements made on dimethyl sulfoxide-d6 solutions, 0.5 M in nucleoside and 0.15 M in mercury, reveal that both CH3 HgCl and HgCl2 bind principally to the sulfur atoms of s6 Guo and s8 Guo. The 13C NMR spectra of the unthiolated nucleosides in the presence of excess (4:1) mercury reveal that HgCl2 binds to N-3 of cytidine, to more than one site on adenosine and guanosine, but not strongly to uridine. Excess HgCl2 shifts the thiocarbonyl carbon atoms in s6 Guo and s8 Guo approx. 16 ppm upfield compared to the free nucleosides, and there is evidence for additional coordination to N-7 of s6 Guo. Binding to the ribose hydroxyl groups is clearly ruled out. At least in these instances, 13C NMR proves to be useful for assigning the mercury (II) binding sites, complementing the results of proton magnetic resonance studies. Proton NMR data for the binding of CH3 HgCl and HgCl2 to s6 Guo and s8 Guo are also presented.
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Mansy S, Tobias RS. Heavy metal-nucleoside interactions. Binding of methylmercury(II) to inosine and catalysis of the isotopic exchange of the C-8 hydrogen studied by 1-H nuclear magnetic resonance and raman difference spectrophotometry. Biochemistry 1975; 14:2952-61. [PMID: 238579 DOI: 10.1021/bi00684a025] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Raman difference spectrophotometry reveals that CH3HgII binds quantitatively to N(1) of inosine at pH 8, substituting for the proton. When N(1) is saturated, binding occurs at a second site. Measurements of the 1-H nuclear magnetic resonance spectra of both inosine and of CH3Hg-II are in agreement with the N(1) binding and indicate that the second site for mercuriation is N(7). This second binding reaction is observed to increase the rate of exchange of the C(8) hydrogen with solvent, consistent with results observed for alkylation at N(7). Coordination of the electrophilic CH3Hg-II to N(7) increases the acidity of H(8), facilitating OHminus--catalyzed proton abstraction and reprotonation by themedium. For comparison, the reaction of CH3Hg-II with [8-2-H]inosine has been studied. Displacement of the N(1) hydrogen upon mercuriation of inosine causes a significant electron delocalization into the ring, increasing the basicity of N(7), and accounting for the synergic effect in metal binding observed originally by Simpson. In contrast, 1-methylinosine interacts only slightly with CH3Hg-II at pH 8. Coordination appears to be at N(7), since H(8) again is observed to exchange rapidly with solvent protons. In acidic solution, pH less than 2, binding to inosine is almost quantitative and exclusively to N(7). The behavior of CH3Hg-II is compared with that of Pt(II) and with Ni(II), Co(II), AND Zn(II). A brief comparison is made among ultraviolet absorption spectrophotometry, nuclear magnetic resonance (NMR), and Raman difference spectrophotometry for studying reactions of nucleosides and nucleotides.
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Mansy S, Frick JP, Tobias RS. Heavy metal-nucleotide interactions. III. The participation of amino groups in the binding of methylmercury (II) to cytidine and adenosine 5'-phosphate in aqueous solution: studies by Raman difference spectrophotometry. BIOCHIMICA ET BIOPHYSICA ACTA 1975; 378:319-32. [PMID: 234751 DOI: 10.1016/0005-2787(75)90177-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Raman difference spectrophotometry has been used to study the interaction of CH3Hg(II) with cytidine and Ado-5'-P at high pH. In contrast to the binding reactions which occur at lower pH or in non-aqueous solvents such as dimethyl sulfoxide, a proton is transferred from the amino group; and the complexes are CH3HgCydH-1 and CH3HgAdoH-1-5'-P. The spectra are significantly different from those of the cationic complexes. The integrated intensities of ligand modes which shift upon metalation can be used to measure the concentration of unreacted ligand and consequently the extent of the reaction. Equilibrium constants for the reactions CH3HgOH + L yields CH3HgLH-1 + H2O were estimated to be log KCyd equals 0.63 plus or minus 0.05 and log KAdo-5'-P equals 0.85 plus or minus 0.05, in fair agreement with values determined under very different conditions by ultraviolet spectrophotometry. The vibrational spectrum of the ligand in CH3HgCydH-1 is virtually the same as that of UrdH-1- which is isoelectronic. The spectrum of the ligand in CH3HgAdoH-1-5'-P is more similar to the isoelectronic base InoH-1-than to Ado-5'-P, although the resemblance is not so close as in the CydH-1---UrdH-1-case. The structures of these complexes are discussed on the basis of their vibrational spectra and similarities in the spectra of related compounds. It is concluded that the CH3Hg(II) binds to the amino nitrogen at high pH with both cytidine and Ado-5'-P. In neutral solution with excess CH3Hg(II), metalation occurs on the amino groups, on the ring, and also on the ribose.
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Gagnon C, Beauchamp A. Metal binding at N1 and N7 in a Silver Nitrate-9-methyladenine complex. Inorganica Chim Acta 1975. [DOI: 10.1016/s0020-1693(00)85709-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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