1
|
Zablon HA, VonHandorf A, Puga A. Mechanisms of chromate carcinogenesis by chromatin alterations. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2023; 96:1-23. [PMID: 36858770 DOI: 10.1016/bs.apha.2022.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In a dynamic environment, organisms must constantly mount an adaptive response to new environmental conditions in order to survive. Novel patterns of gene expression, driven by attendant changes in chromatin architecture, aid in adaptation and survival. Critical mechanisms in the control of gene transcription govern new spatiotemporal chromatin-chromatin interactions that make regulatory DNA elements accessible to the transcription factors that control the response. Consequently, agents that disrupt chromatin structure are likely to have a direct impact on the transcriptional programs of cells and organisms and to drive alterations in fundamental physiological processes. In this regard, hexavalent chromium (Cr(VI)) is of special interest because it interacts directly with cellular proteins, DNA, and other macromolecules, and is likely to upset cell functions that may cause generalized damage to the organism. Here, we will highlight chromium-mediated mechanisms that disrupt chromatin architecture and discuss how these mechanisms are integral to its carcinogenic properties. Emerging evidence indicates that Cr(VI) targets euchromatin, particularly in genomic locations flanking the binding sites of the essential transcription factors CTCF and AP1, and, in so doing, they disrupt nucleosomal architecture. Ultimately, the ensuing changes, if occurring in critical regulatory domains, may establish a new chromatin state, either toxic or adaptive, that will be governed by the corresponding gene transcription changes in key biological processes associated with that state.
Collapse
Affiliation(s)
- Hesbon A Zablon
- Department of Environmental and Public Health Sciences and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Andrew VonHandorf
- Department of Environmental and Public Health Sciences and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Alvaro Puga
- Department of Environmental and Public Health Sciences and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH, United States.
| |
Collapse
|
2
|
Hexavalent chromium disrupts chromatin architecture. Semin Cancer Biol 2021; 76:54-60. [PMID: 34274487 DOI: 10.1016/j.semcancer.2021.07.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/11/2021] [Accepted: 07/12/2021] [Indexed: 12/21/2022]
Abstract
Accessibility of DNA elements and the orchestration of spatiotemporal chromatin-chromatin interactions are critical mechanisms in the regulation of gene transcription. Thus, in an ever-changing milieu, cells mount an adaptive response to environmental stimuli by modulating gene expression that is orchestrated by coordinated changes in chromatin architecture. Correspondingly, agents that alter chromatin structure directly impact transcriptional programs in cells. Heavy metals, including hexavalent chromium (Cr(VI)), are of special interest because of their ability to interact directly with cellular protein, DNA and other macromolecules, resulting in general damage or altered function. In this review we highlight the chromium-mediated mechanisms that promote disruption of chromatin architecture and how these processes are integral to its carcinogenic properties. Emerging evidence shows that Cr(VI) targets nucleosomal architecture in euchromatin, particularly in genomic locations flanking binding sites of the essential transcription factors CTCF and AP1. Ultimately, these changes contribute to an altered chromatin state in critical gene regulatory regions, which disrupts gene transcription in functionally relevant biological processes.
Collapse
|
3
|
Saiz PG, Iglesias N, González Navarrete B, Rosales M, Quintero YM, Reizabal A, Orive J, Fidalgo Marijuan A, Larrea ES, Lopes AC, Lezama L, García A, Lanceros‐Mendez S, Arriortua MI, Fernández de Luis R. Chromium Speciation in Zirconium‐Based Metal–Organic Frameworks for Environmental Remediation. Chemistry 2020; 26:13861-13872. [DOI: 10.1002/chem.202001435] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Indexed: 01/24/2023]
Affiliation(s)
- Paula G. Saiz
- BCMaterials, Basque Center for Materials Applications and Nanostructures UPV/EHU Science Park 48940 Leioa Spain
- Department of Mineralogy and Petrology Science and Technology Faculty University of the Basque Country (UPV/EHU) Barrio Sarriena s/n Leioa Bizkaia 48940 Spain
| | - Naroa Iglesias
- BCMaterials, Basque Center for Materials Applications and Nanostructures UPV/EHU Science Park 48940 Leioa Spain
| | - Bárbara González Navarrete
- Department Water, Environment and Sustainability Advanced Mining Technology Center (AMTC) Facultad de Ciencias FísicasyMatemáticas Universidad de Chile Av. Tupper 2007 Santiago Chile
| | - Maibelin Rosales
- Department Water, Environment and Sustainability Advanced Mining Technology Center (AMTC) Facultad de Ciencias FísicasyMatemáticas Universidad de Chile Av. Tupper 2007 Santiago Chile
| | - Yurieth Marcela Quintero
- Department Water, Environment and Sustainability Advanced Mining Technology Center (AMTC) Facultad de Ciencias FísicasyMatemáticas Universidad de Chile Av. Tupper 2007 Santiago Chile
| | - Ander Reizabal
- BCMaterials, Basque Center for Materials Applications and Nanostructures UPV/EHU Science Park 48940 Leioa Spain
| | - Joseba Orive
- Dept. of Chemical Engineering Biotechnology and Materials Facultad de Ciencias Físicas y Matemáticas Universidad de Chile Av. Beauchef 851 Santiago Chile
| | - Arkaitz Fidalgo Marijuan
- BCMaterials, Basque Center for Materials Applications and Nanostructures UPV/EHU Science Park 48940 Leioa Spain
- Dept. of Organic Chemistry II Science and Technology Faculty University of the Basque Country (UPV/EHU) Barrio Sarriena s/n Leioa Bizkaia 48940 Spain
| | - Edurne S. Larrea
- Le Studium Research Fellow Loire Valley Institute for Advanced Studies Orléans and Tours France
- CEMHTI—UPR3079 CNRS 1 avenue de la Recherche Scientifique 45100 Orléans France
| | - Ana Catarina Lopes
- BCMaterials, Basque Center for Materials Applications and Nanostructures UPV/EHU Science Park 48940 Leioa Spain
| | - Luis Lezama
- Department of Inorganic Chemistry, Science and Technology Faculty University of the Basque Country (UPV/EHU) Barrio Sarriena s/n Leioa Bizkaia 48940 Spain
| | - Andreina García
- Department Water, Environment and Sustainability Advanced Mining Technology Center (AMTC) Facultad de Ciencias FísicasyMatemáticas Universidad de Chile Av. Tupper 2007 Santiago Chile
| | - Senentxu Lanceros‐Mendez
- BCMaterials, Basque Center for Materials Applications and Nanostructures UPV/EHU Science Park 48940 Leioa Spain
- IKERBASQUE Basque Foundation for Science 48013 Bilbao Spain
| | - María Isabel Arriortua
- BCMaterials, Basque Center for Materials Applications and Nanostructures UPV/EHU Science Park 48940 Leioa Spain
- Department of Mineralogy and Petrology Science and Technology Faculty University of the Basque Country (UPV/EHU) Barrio Sarriena s/n Leioa Bizkaia 48940 Spain
| | - Roberto Fernández de Luis
- BCMaterials, Basque Center for Materials Applications and Nanostructures UPV/EHU Science Park 48940 Leioa Spain
| |
Collapse
|
4
|
Zablon HA, VonHandorf A, Puga A. Chromium exposure disrupts chromatin architecture upsetting the mechanisms that regulate transcription. Exp Biol Med (Maywood) 2019; 244:752-757. [PMID: 30935235 PMCID: PMC6567585 DOI: 10.1177/1535370219839953] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
IMPACT STATEMENT This mini-review highlights current evidence on the mechanisms through which hexavalent chromium (Cr(VI)) disrupts transcriptional regulation, an emerging area of interest and one of the central processes by which chromium induces carcinogenesis. Several studies have shown that Cr(VI) causes widespread DNA damage and disrupts epigenetic signatures, suggesting that chromatin may be a direct Cr(VI) target. The findings discussed here suggest that Cr(VI) disrupts transcriptional regulation by causing genomic architecture changes.
Collapse
Affiliation(s)
- Hesbon A Zablon
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Andrew VonHandorf
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Alvaro Puga
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| |
Collapse
|
5
|
Dougherty RJ, Singh J, Krishnan V. Kinetics and thermodynamics of oxidation mediated reaction in l-cysteine and its methyl and ethyl esters in dimethyl sulfoxide-d6 by NMR spectroscopy. J Mol Struct 2017. [DOI: 10.1016/j.molstruc.2016.11.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
6
|
Spectroscopic characterization of genotoxic chromium(V) peptide complexes: Oxidation of Chromium(III) triglycine, tetraglycine and pentaglycine complexes. J Inorg Biochem 2016; 162:227-237. [DOI: 10.1016/j.jinorgbio.2016.06.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 06/07/2016] [Accepted: 06/14/2016] [Indexed: 11/23/2022]
|
7
|
Levina A, McLeod AI, Pulte A, Aitken JB, Lay PA. Biotransformations of Antidiabetic Vanadium Prodrugs in Mammalian Cells and Cell Culture Media: A XANES Spectroscopic Study. Inorg Chem 2015; 54:6707-18. [PMID: 25906315 PMCID: PMC4511291 DOI: 10.1021/ic5028948] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
![]()
The antidiabetic activities of vanadium(V)
and -(IV) prodrugs are determined by their ability to release active
species upon interactions with components of biological media. The
first X-ray absorption spectroscopic study of the reactivity of typical
vanadium (V) antidiabetics, vanadate ([VVO4]3–, A) and a vanadium(IV) bis(maltolato)
complex (B), with mammalian cell cultures has been performed
using HepG2 (human hepatoma), A549 (human lung carcinoma), and 3T3-L1
(mouse adipocytes and preadipocytes) cell lines, as well as the corresponding
cell culture media. X-ray absorption near-edge structure data were
analyzed using empirical correlations with a library of model vanadium(V),
-(IV), and -(III) complexes. Both A and B ([V] = 1.0 mM) gradually converged into similar mixtures of predominantly
five- and six-coordinate VV species (∼75% total
V) in a cell culture medium within 24 h at 310 K. Speciation of V
in intact HepG2 cells also changed with the incubation time (from
∼20% to ∼70% VIV of total V), but it was
largely independent of the prodrug used (A or B) or of the predominant V oxidation state in the medium. Subcellular
fractionation of A549 cells suggested that VV reduction
to VIV occurred predominantly in the cytoplasm, while accumulation
of VV in the nucleus was likely to have been facilitated
by noncovalent bonding to histone proteins. The nuclear VV is likely to modulate the transcription process and to be ultimately
related to cell death at high concentrations of V, which may be important
in anticancer activities. Mature 3T3-L1 adipocytes (unlike for preadipocytes)
showed a higher propensity to form VIV species, despite
the prevalence of VV in the medium. The distinct V biochemistry
in these cells is consistent with their crucial role in insulin-dependent
glucose and fat metabolism and may also point to an endogenous role
of V in adipocytes. The first detailed
speciation study of typical antidiabetic vanadium(V/IV) complexes
in mammalian cell culture systems showed that the complexes decomposed
rapidly in cell culture media and were further metabolized by the
cells, which included interconversions of VV and VIV species.
Collapse
Affiliation(s)
- Aviva Levina
- School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Andrew I McLeod
- School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Anna Pulte
- School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Jade B Aitken
- School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Peter A Lay
- School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| |
Collapse
|
8
|
Abstract
Chromium is ubiquitous in the environment as Cr(III) and Cr(VI) oxidation states, which interconvert under environmentally and biologically relevant conditions (although Cr(III) usually predominates). While Cr(VI) is an established human carcinogen and a major occupational and environmental hazard, Cr(III) has long been regarded as an essential human micronutrient, although recent literature has cast serious doubts on the validity of this postulate. Despite five decades of research, no functional Cr-containing enzymes or cofactors have been characterized conclusively, and several hypotheses on their possible structures have been refuted. Gastrointestinal absorption pathways for both Cr(III) and Cr(VI) are apparent and whole-blood speciation can involve Cr(VI) uptake and reduction by red blood cells, as well as Cr(III) binding to both proteins and low-molecular-mass ligands in the plasma. DNA-damaging effects of Cr(VI) and anti-diabetic activities of Cr(III) are likely to arise from common mechanistic pathways that involve reactive Cr(VI/V/IV) intermediates and kinetically inert Cr(III)-protein and Cr(III)-DNA adducts. Both Cr(III) and Cr(VI) are toxic to plants and microorganisms, particularly Cr(VI) due to its higher bioavailability and redox chemistry. Some bacteria reduce Cr(VI) to Cr(III) without the formation of toxic Cr(V) intermediates and these bacteria are being considered for use in the bioremediation of Cr(VI)-polluted environments.
Collapse
Affiliation(s)
- Peter A. Lay
- School of Chemistry, The University of Sydney Sydney NSW 2006 Australia
| | - Aviva Levina
- School of Chemistry, The University of Sydney Sydney NSW 2006 Australia
| |
Collapse
|
9
|
Bartholomäus R, Irwin JA, Shi L, Smith SM, Levina A, Lay PA. Isolation, Characterization, and Nuclease Activity of Biologically Relevant Chromium(V) Complexes with Monosaccharides and Model Diols. Likely Intermediates in Chromium-Induced Cancers. Inorg Chem 2013; 52:4282-92. [DOI: 10.1021/ic3022408] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ruben Bartholomäus
- Fachbereich Chemie, Philipps-Universität Marburg,
Hans-Meerwein-Strasse, D-35032 Marburg, Germany
- School of Chemistry, The University of Sydney, New South
Wales 2006, Australia
| | - Jennifer A. Irwin
- School of Chemistry, The University of Sydney, New South
Wales 2006, Australia
| | - Liwei Shi
- School of Chemistry, The University of Sydney, New South
Wales 2006, Australia
| | - Siwaporn Meejoo Smith
- School of Chemistry, The University of Sydney, New South
Wales 2006, Australia
- Department of Chemistry, Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand
| | - Aviva Levina
- School of Chemistry, The University of Sydney, New South
Wales 2006, Australia
| | - Peter A. Lay
- School of Chemistry, The University of Sydney, New South
Wales 2006, Australia
| |
Collapse
|
10
|
Quintal SM, dePaula QA, Farrell NP. Zinc finger proteins as templates for metal ion exchange and ligand reactivity. Chemical and biological consequences. Metallomics 2011; 3:121-39. [PMID: 21253649 DOI: 10.1039/c0mt00070a] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Zinc finger reactions with inorganic ions and coordination compounds are as diverse as the zinc fingers themselves. Use of metal ions such as Co(2+) and Cd(2+) has given structural, thermodynamic and kinetic information on zinc fingers and zinc-finger-DNA/RNA interactions. It is a general truism that alteration of the coordination sphere in the finger environment will disrupt the recognition with DNA/RNA and this has implications for mechanism of toxicity and carcinogenesis of metal ions. Structural zinc fingers are susceptible to electrophilic attack and the recognition that the coordination sphere of inorganic compounds may be modulated for control of electrophilic attack on zinc fingers raises the possibility of systematic studies of zinc fingers as drug targets using inorganic chemistry. Some inorganic compounds such as those of As(III) and Au(I) may exert their biological effects through inactivation of zinc fingers and novel approaches to specifically attack the zinc-bound ligands using Co(III)-Schiff bases and Platinum(II)-Nucleobase compounds have been proposed. The genomic importance of zinc fingers suggests that the "coordination chemistry" of zinc fingers themselves is ripe for exploration to design new targets for medicinal inorganic chemistry.
Collapse
Affiliation(s)
- Susana M Quintal
- Department of Chemistry, Virginia Commonwealth University, 1001 W. Main St., Richmond, VA 23284-2006, USA
| | | | | |
Collapse
|
11
|
Levina A, Zhang L, Lay PA. Formation and reactivity of chromium(V)-thiolato complexes: a model for the intracellular reactions of carcinogenic chromium(VI) with biological thiols. J Am Chem Soc 2010; 132:8720-31. [PMID: 20527748 DOI: 10.1021/ja101675w] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The nature of the long-lived EPR-active Cr(V) species observed in cells and biological fluids exposed to carcinogenic Cr(VI) has been definitively assigned from detailed kinetic and spectroscopic analyses of a model reaction of Cr(VI) with p-bromobenzenethiol (RSH) in the presence or absence of cyclic 1,2-diols (LH(2)) in aprotic or mixed solvents. The first definitive structures for Cr(V) complexes with a monodentate thiolato ligand, [Cr(V)O(SR)(4)](-) (g(iso) = 1.9960, A(iso) = 14.7 x 10(-4) cm(-1)), [Cr(V)OL(SR)(2)](-) (g(iso) = 1.9854, A(iso) = (15.8-16.2) x 10(-4) cm(-1)) and [Cr(V)(O)(2)(SR)(2)](-) (g(iso) = 1.9828, A(iso) = 6.8 x 10(-4) cm(-1)) were assigned by EPR spectroscopy and electrospray mass spectrometry. The unusually low A(iso) ((53)Cr) value for the latter species is consistent with its rare four-coordinate, bis-oxido structure. The [Cr(V)OL(SR)(2)](-) species are responsible for the transient g(iso) approximately 1.986 EPR signals observed in living cells and animals treated with Cr(VI) (where RSH and LH(2) are biological thiols and 1,2-diols, respectively). For the first time, concentrations of Cr(V) intermediates formed during the reduction of Cr(VI) were determined by quantitative EPR spectroscopy, and a detailed reaction mechanism was proposed on the basis of stochastic simulations of the kinetic curves for Cr(V) species. A key feature of the proposed mechanism is the regeneration of Cr(V) species in the presence of Cr(VI) through the formation of organic free radicals, followed by the rapid reactions of the formed radicals with Cr(VI). The concentration of Cr(V) grows rapidly at the beginning of the reaction, reaches a steady-state level, and then drops sharply once Cr(VI) is spent. Similar mechanisms are likely to operate during the reduction of Cr(VI) in biological environment rich in reactive C-H bonds, including the oxidative DNA damage by Cr(V) intermediates.
Collapse
Affiliation(s)
- Aviva Levina
- School of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | | | | |
Collapse
|
12
|
Affiliation(s)
- Wolfgang Maret
- Department of Preventive Medicine & Community Health, The University of Texas Medical Branch, Galveston, Texas 77555-1109, USA.
| | | |
Collapse
|
13
|
Nguyen A, Mulyani I, Levina A, Lay PA. Reactivity of Chromium(III) Nutritional Supplements in Biological Media: An X-Ray Absorption Spectroscopic Study. Inorg Chem 2008; 47:4299-309. [DOI: 10.1021/ic7024389] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Annie Nguyen
- School of Chemistry, The University of Sydney, NSW, 2006, Australia
| | - Irma Mulyani
- School of Chemistry, The University of Sydney, NSW, 2006, Australia
| | - Aviva Levina
- School of Chemistry, The University of Sydney, NSW, 2006, Australia
| | - Peter A. Lay
- School of Chemistry, The University of Sydney, NSW, 2006, Australia
| |
Collapse
|
14
|
Levina A, Lay PA. Chemical properties and toxicity of chromium(III) nutritional supplements. Chem Res Toxicol 2008; 21:563-71. [PMID: 18237145 DOI: 10.1021/tx700385t] [Citation(s) in RCA: 160] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The status of Cr(III) as an essential micronutrient for humans is currently under question. No functional Cr(III)-containing biomolecules have been definitively described as yet, and accumulated experience in the use of Cr(III) nutritional supplements (such as [Cr(pic) 3], where pic = 2-pyridinecarboxylato) has shown no measurable benefits for nondiabetic people. Although the use of large doses of Cr(III) supplements may lead to improvements in glucose metabolism for type 2 diabetics, there is a growing concern over the possible genotoxicity of these compounds, particularly of [Cr(pic) 3]. The current perspective discusses chemical transformations of Cr(III) nutritional supplements in biological media, with implications for both beneficial and toxic actions of Cr(III) complexes, which are likely to arise from the same biochemical mechanisms, dependent on concentrations of the reactive species. These species include: (i) partial hydrolysis products of Cr(III) nutritional supplements, which are capable of binding to biological macromolecules and altering their functions; and (ii) highly reactive Cr(VI/V/IV) species and organic radicals, formed in reactions of Cr(III) with biological oxidants. Low concentrations of these species are likely to cause alterations in cell signaling (including enhancement of insulin signaling) through interactions with the active centers of regulatory enzymes in the cell membrane or in the cytoplasm, while higher concentrations are likely to produce genotoxic DNA lesions in the cell nucleus. These data suggest that the potential for genotoxic side-effects of Cr(III) complexes may outweigh their possible benefits as insulin enhancers, and that recommendations for their use as either nutritional supplements or antidiabetic drugs need to be reconsidered in light of these recent findings.
Collapse
|
15
|
Vasant C, Sankaramanivel S, Jana M, Rajaram R, Ramasami T. Non-enzymatic phosphorylation of bovine serum albumin by Cr(V) complexes: role in Cr(VI)-induced phosphorylation and toxicity. Mol Cell Biochem 2006; 275:153-64. [PMID: 16335795 DOI: 10.1007/s11010-005-1206-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Evidence for the non-enzymatic phosphorylation of bovine serum albumin (BSA) by sodium bis(2-ethyl-2-hydroxybutyrato)oxochromate(V), Na[CrVO(ehba)2], 1, sodium bis(2-hydroxy-2-methylbutyrato)oxochromate(V), Na[CrVO(hmba)2], 2 and potassium dichromate, K2Cr2O7, 3 in the presence of labeled adenosine-5'-triphosphate (ATP) under conditions of physiological pH is presented. Aggregation and extent of phosphorylation of BSA mediated by 1, 2 or 3 seems to increase with the concentration and time of incubation of the reaction mixture containing all the reactants. The [gamma-32P] label in ATP is incorporated into aggregates of BSA in the in vitro reaction of the protein with ATP in the presence of 1, 2 or 3. Phosphorylation of BSA by ATP in the absence of 1, 2 or 3 is negligible. Addition of EDTA reverses aggregation of protein and liberates partially the incorporated phosphate label. The stoichiometry of phosphorylation is found to be the highest and is equal to 12.25 mol PO4(3-)/mol BSA in the presence of 500 microM of 1, which decreases to 10.56 mol PO4(3-)/mol BSA after EDTA treatment. Resistance to the removal of phosphate label by EDTA increases with increase in time of incubation. Dialysis of phosphorylated BSA reverses the incorporated [gamma-(32)P] label only partially, indicating the formation of covalent links of phosphate groups to BSA. Evidence for the site of phosphorylation in the reaction mediated by 1, 2 or 3 being hydroxyl side groups of tyrosine and serine/threonine residues has been gained. Based on the results, a possibility that 1, 2 and 3 mimic the function of tyrosine and serine/threonine kinases has been invoked.
Collapse
Affiliation(s)
- Chellappa Vasant
- Biochemistry Laboratory, Central Leather Research Institute, Chennai 600020, India
| | | | | | | | | |
Collapse
|
16
|
Levina A, Harris HH, Lay PA. Binding of chromium(VI) to histones: implications for chromium(VI)-induced genotoxicity. J Biol Inorg Chem 2005; 11:225-34. [PMID: 16362419 DOI: 10.1007/s00775-005-0068-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Accepted: 11/23/2005] [Indexed: 10/25/2022]
Abstract
The first evidence has been obtained for Cr(VI) (chromate) binding to isolated calf thymus (CT) histones under physiological conditions (pH 7.4, Cl(-) concentration 152 mM, 310 K). No significant Cr(VI) binding under the same conditions was observed for other extracellular and intracellular proteins, including albumin, apo-transferrin and G-actin, as well as for CT DNA. The mode of Cr(VI) binding to histones was studied by vibrational, electronic and X-ray absorption (X-ray absorption near-edge structure and X-ray absorption fine structure) spectroscopies and molecular mechanics calculations. A proposed binding mechanism includes electrostatic interactions of CrO(4) (2-) with protonated Lys and Arg residues of histones, as well as the formation of hydrogen bonds with the protein backbone. Similarly, Cr(VI) can bind to nuclear localization signals (typically, Lys- and Arg-rich fragments) of other nuclear proteins. Selective binding of Cr(VI) to newly synthesized nuclear proteins (including histones) in the cytoplasm is likely to be responsible for the active transport of Cr(VI) into the nuclei of living cells.
Collapse
Affiliation(s)
- Aviva Levina
- Centre for Heavy Metals Research, and Centre for Structural Biology and Structural Chemistry, School of Chemistry, The University of Sydney, 2006 Sydney, NSW, Australia
| | | | | |
Collapse
|
17
|
|
18
|
Gez S, Luxenhofer R, Levina A, Codd R, Lay PA. Chromium(V) complexes of hydroxamic acids: formation, structures, and reactivities. Inorg Chem 2005; 44:2934-43. [PMID: 15819581 DOI: 10.1021/ic048317d] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new family of relatively stable Cr(V) complexes, [Cr(V)O(L)(2)](-) (LH(2) = RC(O)NHOH, R = Me, Ph, 2-HO-Ph, or HONHC(O)(CH(2))(6)), has been obtained by the reactions of hydroxamic acids with Cr(VI) in polar aprotic solvents. Similar reactions in aqueous solutions led to the formation of transient Cr(V) species. All complexes have been characterized by electron paramagnetic resonance spectroscopy and electrospray mass spectrometry. A Cr(V) complex of benzohydroxamic acid (1, R = Ph) was isolated in a pure form (as a K(+) salt) and was characterized by X-ray absorption spectroscopy and analytical techniques. Multiple-scattering analysis of X-ray absorption fine structure spectroscopic data for 1 (solid, 10 K) point to a distorted trigonal-bipyramidal structure with trans-oriented Ph groups and Cr-ligand bond lengths of 1.58 A (Cr-O), 1.88 A (Cr-O(C)), and 1.98 A (Cr-O(N)). Under ambient conditions, 1 is stable for days in aprotic solvents but decomposes within minutes in aqueous solutions (maximal stability at pH approximately 7), which leads predominantly to the formation of Cr(III) complexes. Complex 1 readily undergoes ligand-exchange reactions with biological 1,2-diols, including D-glucose and mucin, in neutral aqueous solutions. It differs from most other types of Cr(V) complexes in its biological activity, since no oxidative cleavage of plasmid DNA in vitro and no significant bacterial mutagenicity (in the TA 102 strain of Salmonella typhimurium) was observed for 1. In natural systems, stabilization of Cr(V) by hydroxamato ligands from bacterial-derived siderophores (followed by ligand-exchange reactions with more abundant carbohydrate ligands) may occur during the biological reduction of Cr(VI) in contaminated soils.
Collapse
Affiliation(s)
- Swetlana Gez
- Centre for Heavy Metals Research, School of Chemistry, University of Sydney, NSW, 2006, Australia
| | | | | | | | | |
Collapse
|
19
|
Levina A, Lay PA. Mechanistic studies of relevance to the biological activities of chromium. Coord Chem Rev 2005. [DOI: 10.1016/j.ccr.2004.02.017] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
20
|
Kinetics and mechanism of a trans-tetraazamacrocyclic chromium(III) complex oxidation by hexacyanoferrate(III) in strongly alkaline media. TRANSIT METAL CHEM 2004. [DOI: 10.1007/s11243-004-1568-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
21
|
Weeks CL, Levina A, Dillon CT, Turner P, Fenton RR, Lay PA. Synthesis and Characterization of a Chromium(V) cis-Dioxo Bis(1,10-phenanthroline) Complex and Crystal and Molecular Structures of Its Chromium(III) Precursor. Inorg Chem 2004; 43:7844-56. [PMID: 15554650 DOI: 10.1021/ic049008q] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The first structurally characterized Cr(V) dioxo complex, cis-[CrV(O)2(phen)2](BF4) (2, phen=1,10-phenanthroline) has been synthesized by the oxidation of a related Cr(III) complex, cis-[Cr(III)(phen)2(OH2)2](NO3)3.2.5H2O (1, characterized by X-ray crystallography), with NaOCl in aqueous solutions in the presence of excess NaBF4, and its purity has been confirmed by electrospray mass spectrometry (ESMS), EPR spectroscopy, and analytical techniques. Previously reported methods for the generation of Cr(V)-phen complexes, such as the oxidation of 1 with PbO2 or PhIO, have been shown by ESMS to lead to mixtures of Cr(III), Cr(V), Cr(VI), and in some cases Cr(IV) species, 3. Species 3 was assigned as [CrIV(O)(OH)(phen)2]+, based on ESMS and X-ray absorption spectroscopy measurements. A distorted octahedral structure for 2 (CrO, 1.63 A; Cr-N, 2.04 and 2.16 A) was established by multiple-scattering (MS) modeling of XAFS spectra (solid, 10 K). The validity of the model was verified by a good agreement between the results of MS XAFS fitting and X-ray crystallography for 1 (distorted octahedron; Cr-O, 1.95 A; Cr-N, 2.06 A). Unlike for the well-studied Cr(V) 2-hydroxycarboxylato complexes, 2 was equally or more stable in aqueous media (hours at pH=1-13 and 25 degrees C) compared with polar aprotic solvents. A stable Cr(III)-Cr(VI) dimer, [Cr(III)(Cr(VI)O4)(phen)2]+ (detected by ESMS), is formed during the decomposition of 2 in nonaqueous media. Comparative studies of the oxidation of 1 by NaOCl or PbO2 have shown that [Cr(V)(O)2(phen)2]+ was the active species responsible for the previously reported oxidative DNA damage, bacterial mutagenicity, and increased incidence of micronuclei in mammalian cells, caused by the oxidation products of 1 with PbO2. Efficient oxidation of 1 to a genotoxic species, [Cr(V)(O)2(phen)2]+, in neutral aqueous media by a biological oxidant, hypochlorite, supports the hypothesis on a significant role of reoxidation of Cr(III) complexes, formed during the intracellular reduction of Cr(VI), in Cr(VI)-induced carcinogenicity. Similar oxidation reactions may contribute to the reported adverse effects of a popular nutritional supplement, Cr(III) picolinate.
Collapse
Affiliation(s)
- Colin L Weeks
- Centre for Heavy Metals Research, School of Chemistry, University of Sydney, NSW 2006, Australia
| | | | | | | | | | | |
Collapse
|
22
|
Kinetics and mechanism of a macrocyclic chromium(III) complex oxidation to chromium(IV) by hexacyanoferrate(III) in strongly alkaline media. TRANSIT METAL CHEM 2004. [DOI: 10.1007/s11243-004-4991-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
23
|
Levina A, Codd R, Foran GJ, Hambley TW, Maschmeyer T, Masters AF, Lay PA. X-ray Absorption Spectroscopic Studies of Chromium(V/IV/III)− 2-Ethyl-2-hydroxybutanoato(2−/1−) Complexes. Inorg Chem 2004; 43:1046-55. [PMID: 14753827 DOI: 10.1021/ic030239r] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Structures of the complexes [Cr(V)O(ehba)(2)](-), [Cr(IV)O(ehbaH)(2)](0), and [Cr(III)(ehbaH)(2)(OH(2))(2)](+) (ehbaH(2) = 2-ethyl-2-hydroxybutanoic acid) in frozen aqueous solutions (10 K, [Cr] = 10 mM, 1.0 M ehbaH(2)/ehbaH, pH 3.5) have been determined by single- and multiple-scattering fitting of X-ray absorption fine structure (XAFS) data. An optimal set of fitting parameters has been determined from the XAFS calculations for a compound with known crystal structure, Na[Cr(V)O(ehba)(2)] (solid, 10 K). The structure of the Cr(V) complex [Cr(V)O(ehba)(2)](-) does not change in solution in the presence of excess ligand. Contrary to the earlier suggestions made from the kinetic data (Ghosh, M. C.; Gould, E. S. J. Chem. Soc., Chem. Commun. 1992, 195-196), the structure of the Cr(IV) complex (generated by the Cr(VI) + As(III) + ehbaH(2) reaction) is close to that of the Cr(V) complex (five-coordinate, distorted trigonal bipyramidal) and different from that of the Cr(III) complex (six-coordinate, octahedral). For both Cr(V) and Cr(IV) complexes, some disorder in the position of the oxo group is observed, which is consistent with but not definitive for the presence of geometric isomers. The structure of the Cr(IV) complex differs from that of Cr(V) by protonation of alcoholato groups of the ligands, which leads to significant elongation of the corresponding Cr-O bonds (2.0 vs 1.8 A). This is reflected in the different chemical properties reported previously for the Cr(IV) and Cr(V) complexes, including their reactivities toward DNA and other biomolecules in relation to Cr-induced carcinogenicity.
Collapse
Affiliation(s)
- Aviva Levina
- Centre for Structural Biology and Structural Chemistry, School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia
| | | | | | | | | | | | | |
Collapse
|
24
|
Micellar effect on the kinetics and mechanism of chromium(VI) oxidation of organic substrates. Coord Chem Rev 2004. [DOI: 10.1016/j.cct.2003.10.012] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
25
|
Venkataramanan NS, Premsingh S, Rajagopal S, Pitchumani K. Electronic and steric effects on the oxygenation of organic sulfides and sulfoxides with oxo(salen)chromium(V) complexes. J Org Chem 2003; 68:7460-70. [PMID: 12968901 DOI: 10.1021/jo034558b] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The kinetics of oxygenation of several para-substituted phenyl methyl sulfides and sulfoxides with a series of 5-substituted and sterically hindered oxo(salen)chromium(V) complexes have been studied by a spectrophotometric technique. Though the reaction of sulfides follows simple second-order kinetics, sulfoxides bind strongly with the metal center of the oxidant and the oxygen atom is transferred from the oxidant-sulfoxide adduct to the substrate. The reduction potentials, E(red), of eight Cr(V) complexes correlate well with the Hammett sigma constants, and the reactivity of the metal complexes is in accordance with the E(red) values. The metal complexes carrying bulky tert-butyl groups entail steric effects. Organic sulfides follow a simple electrophilic oxidation mechanism, and the nonligated sulfoxides undergo electrophilic oxidation to sulfones using the oxidant-sulfoxide adduct as the oxidant. Sulfoxides catalyze the Cr(V)-salen complexes' oxygenation of organic sulfides, and the catalytic activity of sulfoxides is comparable to pyridine N-oxide and triphenylphosphine oxide. The rate constants obtained for the oxidation of sulfides and sulfoxides clearly indicate the operation of a pronounced electronic and steric effect in the oxygenation reaction with oxo(salen)chromium(V) complexes.
Collapse
|
26
|
Krepkiy D, Antholine WE, Petering DH. Properties of the reaction of chromate with metallothionein. Chem Res Toxicol 2003; 16:750-6. [PMID: 12807358 DOI: 10.1021/tx020074j] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The reactivity of chromate or Cr(VI) with rabbit liver metallothionein (MT) was explored in this study. Zn(7)-MT reacts very slowly with Cr(VI) in a process characterized by a second-order rate constant of 3.9 x 10(-)(4) M(-)(1) s(-)(1). During the reaction, Zn(2+) was released from the protein. In contrast, apo-MT reduces chromate quicker and in this reaction is much more effective as a reducing agent, when compared to Cys or GSH. The kinetics are consistent with a reaction pathway involving an initial binding step followed by the reduction of Cr(VI). In the process, MT sulfhydryl groups were oxidized at the same rate that Cr(VI) disappeared. A Cr(V) intermediate was detected by EPR spectroscopy immediately upon mixing apo-MT with Cr(VI). The Cr(V) signal decayed during the reaction but was quite stable and could be observed for hours once the supply of thiols was depleted. The g values for the Cr(V) species were 2.014 and 1.987. The kinetics of the reaction of Cr(VI) and the concentration of the intermediate Cr(V) signal were independent of the oxygen concentration and were unaffected by the presence of superoxide dismutase, catalase, or DMSO. In the presence of oxygen, oxy radicals were generated according to ESR spin-trapping experiments with 5,5'-dimethyl-1-pyrroline-N-oxide. Superoxide dismutase decreased and catalase or DMSO largely inhibited the formation of the spin-trapped adduct. Cr(III), the presumed final species of the Cr(VI) reduction, formed a stable complex with apo-MT in the absence of oxygen with an average stoichiometry of two Cr ions bound per protein molecule. Upon addition of O(2), the complex slowly dissociated.
Collapse
Affiliation(s)
- Dmitriy Krepkiy
- Department of Chemistry, PO Box 413, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, USA
| | | | | |
Collapse
|
27
|
Abstract
Chromium(V) glutathione complexes are among the likely reactive intermediates in Cr(VI)-induced genotoxicity and carcinogenicity. The first definitive structure of one such complex, [Cr(V)O(LH(2))(2)](3)(-) (I; LH(5) = glutathione = GSH), isolated from the reaction of Cr(VI) with excess GSH at pH 7.0 (O'Brien, P.; Pratt, J.; Swanson, F. J.; Thornton, P.; Wang, G. Inorg. Chim. Acta 1990, 169, 265-269), has been determined by a combination of electrospray mass spectrometry (ESMS), X-ray absorption spectroscopy (XAS), EPR spectroscopy, and analytical techniques. In addition, Cr(V) complexes of GSH ethyl ester (gamma-Glu-Cys-GlyOEt) have been isolated and characterized by ESMS, and Cr(III) products of the Cr(VI) + GSH reaction have been isolated and characterized by ESMS and XAS. The thiolato and amido groups of the Cys residue in GSH are responsible for the Cr(V) binding in I. The Cr-ligand bond lengths, determined from multiple-scattering XAFS analysis, are as follows: 1.61 A for the oxo donor; 1.99 A for the amido donors; and 2.31 A for the thiolato donors. A significant electron withdrawal from the thiolato groups to Cr(V) in I was evident from the XANES spectra. Rapid decomposition of I in aqueous solutions (pH = 1-13) occurs predominantly by ligand oxidation with the formation of Cr(III) complexes of GSH and GSSG. Maximal half-lives of the Cr(V) species (40-50 s at [Cr] = 1.0 mM and 25 degrees C) are observed at pH 7.5-8.0. The experimental data are in conflict with a recent communication (Gaggelli, E.; Berti, F.; Gaggelli, N.; Maccotta, A.; Valensin, G. J. Am. Chem. Soc. 2001, 123, 8858-8859) on the formation of a Cr(V) dimer as a major product of the Cr(VI) + GSH reaction, which may have resulted from misinterpretation of the ESMS and NMR spectroscopic data.
Collapse
Affiliation(s)
- Aviva Levina
- Centre for Heavy Metal Research, School of Chemistry, University of Sydney, Sydney 2006 NSW, Australia
| | | | | |
Collapse
|
28
|
Maret W. Optical methods for measuring zinc binding and release, zinc coordination environments in zinc finger proteins, and redox sensitivity and activity of zinc-bound thiols. Methods Enzymol 2002; 348:230-7. [PMID: 11885276 DOI: 10.1016/s0076-6879(02)48641-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Wolfgang Maret
- Center for Biochemical and Biophysical Sciences and Medicine, Harvard Medical School, Cambridge, Massachusetts 02139, USA
| |
Collapse
|
29
|
Dolman RC, Deacon GB, Hambley TW. Studies of the binding of a series of platinum(IV) complexes to plasma proteins. J Inorg Biochem 2002; 88:260-7. [PMID: 11897339 DOI: 10.1016/s0162-0134(01)00360-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The platinum(IV) complexes: [PtCl(4)(en)], cis,trans-[PtCl(2)(OAc)(2)(en)], cis,trans-[PtCl(2)(OH)(2)(en)] and trans-[Pt(OH)(2)(ethmal)(en)], encompassing a range of reduction potentials and their platinum(II) analogue [PtCl(2)(en)], have been assayed for their protein binding ability in the presence of albumin, albumin and L-cysteine and RPMI 1640 tissue culture medium supplemented with foetal calf serum (RPMI/FCS). cis,trans-[PtCl(4)(en)] exhibited significant protein binding in all three experiments, in a similar fashion to the platinum(II) complex, presumably as a consequence of its rapid reduction. The remaining three platinum(IV) complexes displayed little if any protein binding, with the greatest amount of binding observed in the RPMI/FCS experiment. The extent of binding in the RPMI/FCS correlated with the reduction potentials of the complexes, with the most readily reduced species binding to the greatest extent.
Collapse
Affiliation(s)
- Rachael C Dolman
- Centre for Heavy Metals Research, School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
| | | | | |
Collapse
|
30
|
Vasant C, Balamurugan K, Rajaram R, Ramasami T. Apoptosis of lymphocytes in the presence of Cr(V) complexes: role in Cr(VI)-induced toxicity. Biochem Biophys Res Commun 2001; 285:1354-60. [PMID: 11478807 DOI: 10.1006/bbrc.2001.5335] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cr(VI) compounds have been declared as a potent occupational carcinogen by IARC (1990) through epidemiological studies among workers in chrome plating, stainless-steel, and pigment industries. Studies relating to the role of intermediate oxidation states such as Cr(V) and Cr(IV) in Cr(VI)-induced carcinogenicity are gaining importance. In this study, issues relating to toxicity elicited by Cr(V) have been addressed and comparisons made with those relating to Cr(VI) employing human peripheral blood lymphocytes. Lymphocytes have been isolated from heparinized blood by Ficoll-Hypaque density gradient centrifugation and exposed to Cr(V) complexes viz. sodium bis(2-ethyl-2-hydroxybutyrato)oxochromate(V), Na[Cr(V)O(ehba)(2)], 1 and sodium bis(2-hydroxy-2-methylbutyrato)oxochromate(V), Na[Cr(V)O(hmba)(2)], 2 and Cr(VI). The phytohemagglutinin (PHA)-induced proliferation of lymphocytes has been found to be inhibited by the two complexes of Cr(V) and chromate Cr(VI) in a time- and concentration-dependent manner. Viability of cells decreases in the presence of Cr(V). Apoptosis appears to be the mode of cell death in the presence of both Cr(V) and Cr(VI). Pretreatment of cells with antioxidants before exposure to chromium(V) complexes reverse apoptosis partially. Possibility for the formation and implication of reactive oxygen species in Cr(V)-induced apoptosis of human lymphocyte cells has been indicated in this investigation. The intermediates of Cr(V) and radical species in the biotoxic pathways elicited by Cr(VI) seems feasible.
Collapse
Affiliation(s)
- C Vasant
- Central Leather Research Institute, Adyar, Chennai, 600 020, India
| | | | | | | |
Collapse
|
31
|
Wilcox DE, Schenk AD, Feldman BM, Xu Y. Oxidation of zinc-binding cysteine residues in transcription factor proteins. Antioxid Redox Signal 2001; 3:549-64. [PMID: 11554444 DOI: 10.1089/15230860152542925] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recent results on the oxidation of cysteine residues that bind zinc in transcription factors and their analogous peptides and in related proteins and model systems are reviewed. Two classes of oxidants, the transition metals and dioxygen, hydrogen peroxide, and related species, are considered, and the role of metal ions in suppressing or enhancing Cys oxidation is a major focus. Cysteines in the zinc-bound structures of transcription factors are less susceptible to oxidation than in the metal-free form, and this appears to correlate with reduced accessibility of the thiolates to oxidants. Substitution of other metal ions for Zn(II) increases the rate of Cys oxidation, apparently through increased oxidant accessibility. Reactions that result in reversible or irreversible oxidation of these zinc-binding cysteines under biological conditions are identified in the context of deleterious implications for gene expression.
Collapse
Affiliation(s)
- D E Wilcox
- Department of Chemistry, Dartmouth College, Hanover, NH 03755, USA.
| | | | | | | |
Collapse
|
32
|
Levina A, Lay PA, Dixon NE. Disproportionation of a model chromium(V) complex causes extensive chromium(III)-DNA binding in vitro. Chem Res Toxicol 2001; 14:946-50. [PMID: 11511167 DOI: 10.1021/tx010077g] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The first direct evidence for the role of Cr(V) complexes in the formation of potentially mutagenic Cr(III)-DNA adducts has been obtained. A model complex for the stabilized Cr(V) species formed in Cr(VI)-treated cells, [Cr(V)O(ehba)(2)]-[ehba = 2-ethyl-2-hydroxybutanoato(2-)], rapidly disproportionates in HEPES buffers at pH 7.4 [3 Cr(V) --> 2 Cr(VI) + Cr(III)], and the formed Cr(III) species undergo efficient ionic binding to DNA, followed by slower covalent binding. The extent of Cr(III)-DNA binding significantly exceeds that caused by [Cr(III)(OH(2))(6)](3+) or by the Cr(III) products of Cr(VI) reductions under similar conditions. The Cr(III)-DNA binding can be dramatically reduced by the ability of the reaction medium (e.g., phosphate buffer) to form complexes with Cr(III) during and after the disproportionation reaction. A mechanism of Cr(III)-DNA binding caused by Cr(V) disproportionation has been proposed on the basis of stoichiometric and kinetic studies.
Collapse
Affiliation(s)
- A Levina
- Centre for Heavy Metals Research, School of Chemistry, University of Sydney, Sydney 2006 NSW, Australia
| | | | | |
Collapse
|