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Zhao YQ, Duan J, Yu L, Kim I, Wang Y, Ma YC, Zou CG, Zhou Y, Zhang JF, Kim JS. Metabolic iron detection through divalent metal transporter 1 and ferroportin mediated cocktail fluorogenic probes. Chem Commun (Camb) 2021; 57:7902-7905. [PMID: 34286752 DOI: 10.1039/d1cc03150c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A cocktail [1 + 2] dual-fluorescent probe system was developed to realize the real-time visualization of dynamic iron state changes between Fe2+ and Fe3+ at the cellular level and in multicellular organisms, providing insights into the effect of DMT1 and ferroportin on iron regulation.
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Affiliation(s)
- Yu-Qiang Zhao
- College of Chemical Science and Technology, Yunnan University, Kunming 650091, P. R. China.
| | - Jiahong Duan
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, Yunnan 650091, China
| | - Le Yu
- College of Chemical Science and Technology, Yunnan University, Kunming 650091, P. R. China. and Department of Chemistry, Korea University, Seoul 02841, Korea.
| | - Ilwha Kim
- Department of Chemistry, Korea University, Seoul 02841, Korea.
| | - Yumin Wang
- College of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650500, P. R. China.
| | - Yi-Cheng Ma
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, Yunnan 650091, China
| | - Cheng-Gang Zou
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, Yunnan 650091, China
| | - Ying Zhou
- College of Chemical Science and Technology, Yunnan University, Kunming 650091, P. R. China.
| | - Jun Feng Zhang
- College of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650500, P. R. China.
| | - Jong Seung Kim
- Department of Chemistry, Korea University, Seoul 02841, Korea.
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Murgas CJ, Green SP, Forney AK, Korba RM, An SS, Kitten T, Lucas HR. Intracellular Metal Speciation in Streptococcus sanguinis Establishes SsaACB as Critical for Redox Maintenance. ACS Infect Dis 2020; 6:1906-1921. [PMID: 32329608 DOI: 10.1021/acsinfecdis.0c00132] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Streptococcus sanguinis is an oral commensal bacterium, but it can colonize pre-existing heart valve vegetations if introduced into the bloodstream, leading to infective endocarditis. Loss of Mn- or Fe-cofactored virulence determinants are thought to result in weakening of this bacterium. Indeed, intracellular Mn accumulation mediated by the lipoprotein SsaB, a component of the SsaACB transporter complex, has been shown to promote virulence for endocarditis and O2 tolerance. To delineate intracellular metal-ion abundance and redox speciation within S. sanguinis, we developed a protocol exploiting two spectroscopic techniques, Inductively coupled plasma-optical emission spectrometry (ICP-OES) and electron paramagnetic resonance (EPR) spectroscopy, to respectively quantify total intracellular metal concentrations and directly measure redox speciation of Fe and Mn within intact whole-cell samples. Addition of the cell-permeable siderophore deferoxamine shifts the oxidation states of accessible Fe and Mn from reduced-to-oxidized, as verified by magnetic moment calculations, aiding in the characterization of intracellular metal pools and metal sequestration levels for Mn2+ and Fe. We have applied this methodology to S. sanguinis and an SsaACB knockout strain (ΔssaACB), indicating that SsaACB mediates both Mn and Fe uptake, directly influencing the metal-ion pools available for biological inorganic pathways. Mn supplementation of ΔssaACB returns total intracellular Mn to wild-type levels, but it does not restore wild-type redox speciation or distribution of metal cofactor availability for either Mn or Fe. Our results highlight the biochemical basis for S. sanguinis oxidative resistance, revealing a dynamic role for SsaACB in controlling redox homeostasis by managing the intracellular Fe/Mn composition and distribution.
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Affiliation(s)
- Cody J. Murgas
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Shannon P. Green
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia 23298, United States
- Department of Microbiology & Immunology, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Ashley K. Forney
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Rachel M. Korba
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Seon-Sook An
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Todd Kitten
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia 23298, United States
- Department of Microbiology & Immunology, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Heather R. Lucas
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
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Sebastian J, Swaminath S, Nair RR, Jakkala K, Pradhan A, Ajitkumar P. De Novo Emergence of Genetically Resistant Mutants of Mycobacterium tuberculosis from the Persistence Phase Cells Formed against Antituberculosis Drugs In Vitro. Antimicrob Agents Chemother 2017; 61:e01343-16. [PMID: 27895008 PMCID: PMC5278719 DOI: 10.1128/aac.01343-16] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2016] [Accepted: 11/16/2016] [Indexed: 12/19/2022] Open
Abstract
Bacterial persisters are a subpopulation of cells that can tolerate lethal concentrations of antibiotics. However, the possibility of the emergence of genetically resistant mutants from antibiotic persister cell populations, upon continued exposure to lethal concentrations of antibiotics, remained unexplored. In the present study, we found that Mycobacterium tuberculosis cells exposed continuously to lethal concentrations of rifampin (RIF) or moxifloxacin (MXF) for prolonged durations showed killing, RIF/MXF persistence, and regrowth phases. RIF-resistant or MXF-resistant mutants carrying clinically relevant mutations in the rpoB or gyrA gene, respectively, were found to emerge at high frequency from the RIF persistence phase population. A Luria-Delbruck fluctuation experiment using RIF-exposed M. tuberculosis cells showed that the rpoB mutants were not preexistent in the population but were formed de novo from the RIF persistence phase population. The RIF persistence phase M. tuberculosis cells carried elevated levels of hydroxyl radical that inflicted extensive genome-wide mutations, generating RIF-resistant mutants. Consistent with the elevated levels of hydroxyl radical-mediated genome-wide random mutagenesis, MXF-resistant M. tuberculosis gyrA de novo mutants could be selected from the RIF persistence phase cells. Thus, unlike previous studies, which showed emergence of genetically resistant mutants upon exposure of bacteria for short durations to sublethal concentrations of antibiotics, our study demonstrates that continuous prolonged exposure of M. tuberculosis cells to lethal concentrations of an antibiotic generates antibiotic persistence phase cells that form a reservoir for the generation of genetically resistant mutants to the same antibiotic or another antibiotic. These findings may have clinical significance in the emergence of drug-resistant tubercle bacilli.
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Affiliation(s)
- Jees Sebastian
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India
| | - Sharmada Swaminath
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India
| | - Rashmi Ravindran Nair
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India
| | - Kishor Jakkala
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India
| | - Atul Pradhan
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India
| | - Parthasarathi Ajitkumar
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India
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Kumar P, Bulk M, Webb A, van der Weerd L, Oosterkamp TH, Huber M, Bossoni L. A novel approach to quantify different iron forms in ex-vivo human brain tissue. Sci Rep 2016; 6:38916. [PMID: 27941952 PMCID: PMC5150947 DOI: 10.1038/srep38916] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 11/14/2016] [Indexed: 01/28/2023] Open
Abstract
We propose a novel combination of methods to study the physical properties of ferric ions and iron-oxide nanoparticles in post-mortem human brain, based on the combination of Electron Paramagnetic Resonance (EPR) and SQUID magnetometry. By means of EPR, we derive the concentration of the low molecular weight iron pool, as well as the product of its electron spin relaxation times. Additionally, by SQUID magnetometry we identify iron mineralization products ascribable to a magnetite/maghemite phase and a ferrihydrite (ferritin) phase. We further derive the concentration of magnetite/maghemite and of ferritin nanoparticles. To test out the new combined methodology, we studied brain tissue of an Alzheimer’s patient and a healthy control. Finally, we estimate that the size of the magnetite/maghemite nanoparticles, whose magnetic moments are blocked at room temperature, exceeds 40–50 nm, which is not compatible with the ferritin protein, the core of which is typically 6–8 nm. We believe that this methodology could be beneficial in the study of neurodegenerative diseases such as Alzheimer’s Disease which are characterized by abnormal iron accumulation in the brain.
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Affiliation(s)
- Pravin Kumar
- Huygens-Kamerlingh Onnes Laboratory, Leiden University, 2333 CA Leiden, The Netherlands
| | - Marjolein Bulk
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.,Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Andrew Webb
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Louise van der Weerd
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.,Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Tjerk H Oosterkamp
- Huygens-Kamerlingh Onnes Laboratory, Leiden University, 2333 CA Leiden, The Netherlands
| | - Martina Huber
- Huygens-Kamerlingh Onnes Laboratory, Leiden University, 2333 CA Leiden, The Netherlands
| | - Lucia Bossoni
- Huygens-Kamerlingh Onnes Laboratory, Leiden University, 2333 CA Leiden, The Netherlands
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Goel A, Umar S, Nag P, Sharma A, Kumar L, Shamsuzzama S, Hossain Z, Gayen JR, Nazir A. A dual colorimetric-ratiometric fluorescent probe NAP-3 for selective detection and imaging of endogenous labile iron(iii) pools in C. elegans. Chem Commun (Camb) 2015; 51:5001-4. [DOI: 10.1039/c4cc09798j] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The first dual colorimetric and ratiometric fluorescent probe NAP-3 for selective visualization of labile iron(iii) pools in Caenorhabditis elegans is reported.
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Affiliation(s)
- Atul Goel
- Medicinal and Process Chemistry Division
- CSIR-Central Drug Research Institute
- Lucknow 226031
- India
| | - Shahida Umar
- Medicinal and Process Chemistry Division
- CSIR-Central Drug Research Institute
- Lucknow 226031
- India
| | - Pankaj Nag
- Medicinal and Process Chemistry Division
- CSIR-Central Drug Research Institute
- Lucknow 226031
- India
| | - Ashutosh Sharma
- Medicinal and Process Chemistry Division
- CSIR-Central Drug Research Institute
- Lucknow 226031
- India
| | - Lalit Kumar
- Department of Toxicology
- CSIR-Central Drug Research Institute
- Lucknow 226031
- India
| | | | - Zakir Hossain
- Department of Pharmacokinetics and Metabolism
- CSIR-Central Drug Research Institute
- Lucknow 226031
- India
| | - Jiaur R. Gayen
- Department of Pharmacokinetics and Metabolism
- CSIR-Central Drug Research Institute
- Lucknow 226031
- India
| | - Aamir Nazir
- Department of Toxicology
- CSIR-Central Drug Research Institute
- Lucknow 226031
- India
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Chekhun VF, Lukyanova NY, Burlaka CACP, Bezdenezhnykh NA, Shpyleva SI, Tryndyak VP, Beland FA, Pogribny IP. Iron metabolism disturbances in the MCF-7 human breast cancer cells with acquired resistance to doxorubicin and cisplatin. Int J Oncol 2013; 43:1481-6. [PMID: 23969999 DOI: 10.3892/ijo.2013.2063] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 06/24/2013] [Indexed: 01/11/2023] Open
Abstract
The development of resistance of cancer cells to therapeutic agents is the major obstacle in the successful treatment of breast cancer and the main cause of breast cancer recurrence. The results of several studies have demonstrated an important role of altered cellular iron metabolism in the progression of breast cancer and suggested that iron metabolism may be involved in the acquisition of a cancer cell drug-resistant phenotype. In the present study, we show that human MCF-7 breast cancer cells with an acquired resistance to the chemotherapeutic drugs doxorubicin (MCF-7/DOX) and cisplatin (MCF-7/CDDP) exhibited substantial alterations in the intracellular iron content and levels of iron-regulatory proteins involved in the cellular uptake, storage and export of iron, especially in profoundly increased levels of ferritin light chain (FTL) protein. The increased levels of FTL in breast cancer indicate that FTL may be used as a diagnostic and prognostic marker for breast cancer. Additionally, we demonstrate that targeted downregulation of FTL protein by the microRNA miR-133a increases sensitivity of MCF-7/DOX and MCF-7/CDDP cells to doxorubicin and cisplatin. These results suggest that correction of iron metabolism abnormalities may substantially improve the efficiency of breast cancer treatment.
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Affiliation(s)
- Vasyl F Chekhun
- Department of Mechanisms of Anticancer Therapy, R.E. Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology, Kiev, Ukraine
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Rangel NA, Lin L, Rakariyatham K, Bach A, Trinh K, Clement MHS, Srinivasan C. Unincorporated iron pool is linked to oxidative stress and iron levels in Caenorhabditis elegans. Biometals 2012; 25:971-85. [PMID: 22684251 DOI: 10.1007/s10534-012-9563-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 05/22/2012] [Indexed: 11/28/2022]
Abstract
Free radicals or reactive oxygen species (ROS) are relatively short-lived and are difficult to measure directly; so indirect methods have been explored for measuring these transient species. One technique that has been developed using Escherichia coli and Saccharomyces cerevisiae systems, relies on a connection between elevated superoxide levels and the build-up of a high-spin form of iron (Fe(III)) that is detectable by electron paramagnetic resonance (EPR) spectroscopy at g = 4.3. This form of iron is referred to as "free" iron. EPR signals at g = 4.3 are commonly encountered in biological samples owing to mononuclear high-spin (S = 5/2) Fe(III) ions in sites of low symmetry. Unincorporated iron in this study refers to this high-spin Fe(III) that is captured by desferrioxamine which is detected by EPR at g value of 4.3. Previously, we published an adaptation of Fe(III) EPR methodology that was developed for Caenorhabditis elegans, a multi-cellular organism. In the current study, we have systematically characterized various factors that modulate this unincorporated iron pool. Our results demonstrate that the unincorporated iron as monitored by Fe(III) EPR at g = 4.3 increased under conditions that were known to elevate steady-state ROS levels in vivo, including: paraquat treatment, hydrogen peroxide exposure, heat shock treatment, or exposure to higher growth temperature. Besides the exogenous inducers of oxidative stress, physiological aging, which is associated with elevated ROS and ROS-mediated macromolecular damage, also caused a build-up of this iron. In addition, increased iron availability increased the unincorporated iron pool as well as generalized oxidative stress. Overall, unincorporated iron increased under conditions of oxidative stress with no change in total iron levels. However, when total iron levels increased in vivo, an increase in both the pool of unincorporated iron and oxidative stress was observed suggesting that the status of the unincorporated iron pool is linked to oxidative stress and iron levels.
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Affiliation(s)
- Natalie A Rangel
- Department of Chemistry and Biochemistry, California State University Fullerton, Fullerton, CA 92834, USA
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Valentini S, Cabreiro F, Ackerman D, Alam MM, Kunze MB, Kay CW, Gems D. Manipulation of in vivo iron levels can alter resistance to oxidative stress without affecting ageing in the nematode C. elegans. Mech Ageing Dev 2012; 133:282-90. [PMID: 22445852 PMCID: PMC3449239 DOI: 10.1016/j.mad.2012.03.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 02/16/2012] [Accepted: 03/06/2012] [Indexed: 01/27/2023]
Abstract
Iron-catalyzed generation of free radicals leads to molecular damage in vivo, and has been proposed to contribute to organismal ageing. Here we investigate the role of free iron in ageing in the nematode Caenorhabditis elegans. Media supplementation with Fe(III) increased free iron levels in vivo, as detected by continuous-wave electron paramagnetic resonance spectroscopy and elevated expression of the iron-sensitive reporter transgene pftn-1::gfp. Increased free iron levels caused elevated levels of protein oxidation and hypersensitivity to tert-butyl hydroperoxide (t-BOOH) given 9 mM Fe(III) or greater, but 15 mM Fe(III) or greater was required to reduce lifespan. Treatment with either an iron chelator (deferoxamine) or over-expression of ftn-1, encoding the iron sequestering protein ferritin, increased resistance to t-BOOH and, in the latter case, reduced protein oxidation, but did not increase lifespan. Expression of ftn-1 is greatly increased in long-lived daf-2 insulin/IGF-1 receptor mutants. In this context, deletion of ftn-1 decreased t-BOOH resistance, but enhanced both daf-2 mutant longevity and constitutive dauer larva formation, suggesting an effect of ferritin on signaling. These results show that high levels of iron can increase molecular damage and reduce lifespan, but overall suggest that iron levels within the normal physiological range do not promote ageing in C. elegans.
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Affiliation(s)
- Sara Valentini
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Filipe Cabreiro
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Daniel Ackerman
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Muhammed M. Alam
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Micha B.A. Kunze
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Christopher W.M. Kay
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH,UK
| | - David Gems
- Institute of Healthy Ageing, and Research Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
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Botta G, Turn CS, Quintyne NJ, Kirchman PA. Increased iron supplied through Fet3p results in replicative life span extension of Saccharomyces cerevisiae under conditions requiring respiratory metabolism. Exp Gerontol 2011; 46:827-32. [PMID: 21798334 DOI: 10.1016/j.exger.2011.07.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 07/07/2011] [Accepted: 07/11/2011] [Indexed: 01/05/2023]
Abstract
We have previously shown that copper supplementation extends the replicative life span of Saccharomyces cerevisiae when grown under conditions forcing cells to respire. We now show that copper's effect on life span is through Fet3p, a copper containing enzyme responsible for high affinity transport of iron into yeast cells. Life span extensions can also be obtained by supplementing the growth medium with 1mM ferric chloride. Extension by high iron levels is still dependent on the presence of Fet3p. Life span extension by iron or copper requires growth on media containing glycerol as the sole carbon source, which forces yeast to respire. Yeast grown on glucose containing media supplemented with iron show no extension of life span. The iron associated with cells grown in media supplemented with copper or iron is 1.4-1.8 times that of cells grown without copper or iron supplementation. As with copper supplementation, iron supplementation partially rescues the life span of superoxide dismutase mutants. Cells grown with copper supplementation display decreased production of superoxide as measured by dihydroethidium staining.
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Affiliation(s)
- Gabriela Botta
- Department of Biological Sciences, Florida Atlantic University, Boca Raton, FL 33431, United States.
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Bou-Abdallah F, Chasteen ND. Spin concentration measurements of high-spin (g' = 4.3) rhombic iron(III) ions in biological samples: theory and application. J Biol Inorg Chem 2007; 13:15-24. [PMID: 17932693 DOI: 10.1007/s00775-007-0304-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2007] [Accepted: 09/27/2007] [Indexed: 10/22/2022]
Abstract
Electron paramagnetic resonance (EPR) signals at g' = 4.3 are commonly encountered in biological samples owing to mononuclear high-spin (S = 5/2) Fe3+ ions in sites of low symmetry. The present study was undertaken to develop the experimental method and a suitable g' = 4.3 intensity standard and for accurately quantifying the amount of Fe3+ responsible for such signals. By following the work of Aasa and Vänngård (J. Magn. Reson. 19:308-315, 1975), we present equations relating the EPR intensity of S = 5/2 ions to the intensities of S = 1/2 standards more commonly employed in EPR spectrometry. Of the chelates tested, Fe3+-EDTA (1:3 ratio) in 1:3 glycerol/water (v/v), pH 2, was found to be an excellent standard for frozen-solution S = 5/2 samples at 77 K. The spin concentrations of Cu2+-EDTA and aqua VO2+, both S = 1/2 ions, and of Fe3+-transferrin, an S = 5/2 ion, were measured against this standard and found to agree within 2.2% of their known metal ion concentrations. Relative standard deviations of +/-3.6, +/-5.3 and +/-2.9% in spin concentration were obtained for the three samples, respectively. The spin concentration determined for Fe3+-desferrioxamine of known Fe3+ concentration was anomalously low suggesting the presence of EPR-silent multimeric iron species in solution.
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Affiliation(s)
- Fadi Bou-Abdallah
- Department of Chemistry, University of New Hampshire, Durham, NH 03824, USA
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