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Hausladen A, Qian Z, Zhang R, Premont RT, Stamler JS. Optimized S-nitrosohemoglobin synthesis in red blood cells to preserve hypoxic vasodilation via βCys93. J Pharmacol Exp Ther 2022; 382:1-10. [PMID: 35512801 PMCID: PMC10389762 DOI: 10.1124/jpet.122.001194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 04/25/2022] [Indexed: 11/22/2022] Open
Abstract
Classic physiology links tissue hypoxia to oxygen delivery through control of microvascular blood flow (autoregulation of blood flow). Hemoglobin (Hb) serves both as the source of oxygen and the mediator of microvascular blood flow through its ability to release vasodilatory S-nitrosothiol (SNO) in proportion to degree of hypoxia. β-globin Cys93Ala (βCys93Ala) mutant mice deficient in S-nitrosohemoglobin (SNO-Hb) show profound deficits in microvascular blood flow and tissue oxygenation that recapitulate microcirculatory dysfunction in multiple clinical conditions. However, the means to replete SNO in mouse RBCs in order to restore RBC function is not known. In particular, while methods have been developed to selectively S-nitrosylate βCys93 in human Hb and intact human RBCs, conditions have not been optimized for mouse RBCs that are used experimentally. Here we show that loading SNO onto Hb in mouse RBC lysates can be achieved with high stoichiometry and β-globin selectivity. However, S-nitrosylation of Hb within intact mouse RBCs is ineffective under conditions that work well with human RBCs, and levels of metHb are prohibitively high. We develop an optimized method that loads SNO in mouse RBCs to maintain vasodilation under hypoxia and show that loss of SNO loading in βCys93Ala mutant RBCs results in reduced vasodilation. We also demonstrate that differences in SNO/met/nitrosyl Hb stoichiometry can account for differences in RBC function among studies. RBCs loaded with quasi-physiological amounts of SNO-Hb will produce vasodilation proportionate to hypoxia, whereas RBCs loaded with higher amounts lose allosteric regulation, thus inducing vasodilation at both high and low oxygen level. Significance Statement Red blood cells from mice exhibit poor hemoglobin S-nitrosylation under conditions used for human RBCs, frustrating tests of vasodilatory activity. Using an optimized S-nitrosylation protocol, mouse RBCs exhibit hypoxic vasodilation that is significantly reduced in hemoglobin ββCys93Ala mutant RBCs that cannot carry S-nitrosothiol allosterically, providing genetic validation for the role of bCys93 in oxygen delivery.
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Affiliation(s)
- Alfred Hausladen
- Institute for Transformative Molecular Medicine, Case Western Reserve University, United States
| | - Zhaoxia Qian
- Institute for Transformative Molecular Medicine, Case Western Reserve University, United States
| | - Rongli Zhang
- Institute for Transformative Molecular Medicine, Case Western Reserve University, United States
| | - Richard T Premont
- Institute for Transformative Molecular Medicine, Case Western Reserve University, United States
| | - Jonathan S Stamler
- Institute for Transformative Molecular Medicine, Case Western Reserve University, United States
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Premont RT, Singel DJ, Stamler JS. The enzymatic function of the honorary enzyme: S-nitrosylation of hemoglobin in physiology and medicine. Mol Aspects Med 2022; 84:101056. [PMID: 34852941 PMCID: PMC8821404 DOI: 10.1016/j.mam.2021.101056] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 11/22/2021] [Accepted: 11/24/2021] [Indexed: 11/16/2022]
Abstract
The allosteric transition within tetrameric hemoglobin (Hb) that allows both full binding to four oxygen molecules in the lung and full release of four oxygens in hypoxic tissues would earn Hb the moniker of 'honorary enzyme'. However, the allosteric model for oxygen binding in hemoglobin overlooked the essential role of blood flow in tissue oxygenation that is essential for life (aka autoregulation of blood flow). That is, blood flow, not oxygen content of blood, is the principal determinant of oxygen delivery under most conditions. With the discovery that hemoglobin carries a third biologic gas, nitric oxide (NO) in the form of S-nitrosothiol (SNO) at β-globin Cys93 (βCys93), and that formation and export of SNO to dilate blood vessels are linked to hemoglobin allostery through enzymatic activity, this title is honorary no more. This chapter reviews evidence that hemoglobin formation and release of SNO is a critical mediator of hypoxic autoregulation of blood flow in tissues leading to oxygen delivery, considers the physiological implications of a 3-gas respiratory cycle (O2/NO/CO2) and the pathophysiological consequences of its dysfunction. Opportunities for therapeutic intervention to optimize oxygen delivery at the level of tissue blood flow are highlighted.
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Affiliation(s)
- Richard T Premont
- Institute for Transformative Molecular Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA; Harrington Discovery Institute, University Hospitals Cleveland Medical Center, Cleveland, OH, 44106, USA
| | - David J Singel
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717, USA
| | - Jonathan S Stamler
- Institute for Transformative Molecular Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA; Harrington Discovery Institute, University Hospitals Cleveland Medical Center, Cleveland, OH, 44106, USA.
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3
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Zhang R, Hausladen A, Qian Z, Liao X, Premont RT, Stamler JS. Hypoxic vasodilatory defect and pulmonary hypertension in mice lacking hemoglobin β-cysteine93 S-nitrosylation. JCI Insight 2021; 7:155234. [PMID: 34914637 PMCID: PMC8855790 DOI: 10.1172/jci.insight.155234] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 12/15/2021] [Indexed: 11/25/2022] Open
Abstract
Systemic hypoxia is characterized by peripheral vasodilation and pulmonary vasoconstriction. However, the system-wide mechanism for signaling hypoxia remains unknown. Accumulating evidence suggests that hemoglobin (Hb) in RBCs may serve as an O2 sensor and O2-responsive NO signal transducer to regulate systemic and pulmonary vascular tone, but this remains unexamined at the integrated system level. One residue invariant in mammalian Hbs, β-globin cysteine93 (βCys93), carries NO as vasorelaxant S-nitrosothiol (SNO) to autoregulate blood flow during O2 delivery. βCys93Ala mutant mice thus exhibit systemic hypoxia despite transporting O2 normally. Here, we show that βCys93Ala mutant mice had reduced S-nitrosohemoglobin (SNO-Hb) at baseline and upon targeted SNO repletion and that hypoxic vasodilation by RBCs was impaired in vitro and in vivo, recapitulating hypoxic pathophysiology. Notably, βCys93Ala mutant mice showed marked impairment of hypoxic peripheral vasodilation and developed signs of pulmonary hypertension with age. Mutant mice also died prematurely with cor pulmonale (pulmonary hypertension with right ventricular dysfunction) when living under low O2. Altogether, we identify a major role for RBC SNO in clinically relevant vasodilatory responses attributed previously to endothelial NO. We conclude that SNO-Hb transduces the integrated, system-wide response to hypoxia in the mammalian respiratory cycle, expanding a core physiological principle.
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Affiliation(s)
- Rongli Zhang
- Institute for Transformative Molecular Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, United States of America
| | - Alfred Hausladen
- Institute for Transformative Molecular Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, United States of America
| | - Zhaoxia Qian
- Institute for Transformative Molecular Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, United States of America
| | - Xudong Liao
- Cardiovascular Research Institute, Case Western Reserve University School of Medicine, Cleveland, United States of America
| | - Richard T Premont
- Institute for Transformative Molecular Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, United States of America
| | - Jonathan S Stamler
- Institute for Transformative Molecular Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, United States of America
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4
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Premont RT, Reynolds JD, Zhang R, Stamler JS. Red Blood Cell-Mediated S-Nitrosohemoglobin-Dependent Vasodilation: Lessons Learned from a β-Globin Cys93 Knock-In Mouse. Antioxid Redox Signal 2021; 34:936-961. [PMID: 32597195 PMCID: PMC8035927 DOI: 10.1089/ars.2020.8153] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 06/25/2020] [Indexed: 12/25/2022]
Abstract
Significance: Red blood cell (RBC)-mediated vasodilation plays an important role in oxygen delivery. This occurs through hemoglobin actions, at least in significant part, to convert heme-bound nitric oxide (NO) (in tense [T]/deoxygenated-state hemoglobin) into vasodilator S-nitrosothiol (SNO) (in relaxed [R]/oxygenated-state hemoglobin), convey SNO through the bloodstream, and release it into tissues to increase blood flow. The coupling of hemoglobin R/T state allostery, both to NO conversion into SNO and to SNO release (along with oxygen), under hypoxia supports the model of a three-gas respiratory cycle (O2/NO/CO2). Recent Advances: Oxygenation of tissues is dependent on a single, strictly conserved Cys residue in hemoglobin (βCys93). Hemoglobin couples SNO formation/release at βCys93 to O2 binding/release at hemes ("thermodynamic linkage"). Mice bearing βCys93Ala hemoglobin that is unable to generate SNO-βCys93 establish that SNO-hemoglobin is important for R/T allostery-regulated vasodilation by RBCs that couple blood flow to tissue oxygenation. Critical Issues: The model for RBC-mediated vasodilation originally proposed by Stamler et al. in 1996 has been largely validated: SNO-βCys93 forms in vivo, dilates blood vessels, and is hypoxia-regulated, and RBCs actuate vasodilation proportionate to hypoxia. Numerous compensations in βCys93Ala animals to alleviate tissue hypoxia (discussed herein) are predicted to preserve vasodilatory responses of RBCs but impair linkage to R/T transition in hemoglobin. This is borne out by loss of responsivity of mutant RBCs to oxygen, impaired blood flow responses to hypoxia, and tissue ischemia in βCys93-mutant animals. Future Directions: SNO-hemoglobin mediates hypoxic vasodilation in the respiratory cycle. This fundamental physiology promises new insights in vascular diseases and blood disorders.
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Affiliation(s)
- Richard T. Premont
- Institute for Transformative Molecular Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
- Harrington Discovery Institute, University Hospitals Cleveland Medical Center, Cleveland, Ohio, USA
| | - James D. Reynolds
- Institute for Transformative Molecular Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
- Harrington Discovery Institute, University Hospitals Cleveland Medical Center, Cleveland, Ohio, USA
- Department of Anesthesiology and Perioperative Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Rongli Zhang
- Institute for Transformative Molecular Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
- Department of Medicine, Cardiovascular Research Institute, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Jonathan S. Stamler
- Institute for Transformative Molecular Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
- Harrington Discovery Institute, University Hospitals Cleveland Medical Center, Cleveland, Ohio, USA
- Department of Medicine, Cardiovascular Research Institute, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
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Stamler JS, Reynolds JD, Hess DT. Letter by Stamler et al Regarding Article, "Nitrite and S-Nitrosohemoglobin Exchange Across the Human Cerebral and Femoral Circulation: Relationship to Basal and Exercise Blood Flow Responses to Hypoxia". Circulation 2019; 135:e1135-e1136. [PMID: 28606954 DOI: 10.1161/circulationaha.117.027071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Jonathan S Stamler
- From Institute for Transformative Molecular Medicine, Case Western Reserve University School of Medicine and University Hospitals Cleveland Medical Center, OH (J.S.S., J.D.R., D.T.H.); Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH (J.S.S., D.T.H.); Harrington Discovery Institute, University Hospitals Cleveland Medical Center, OH (J.S.S., J.D.R.); Department of Anesthesiology and Perioperative Medicine, Case Western Reserve University School of Medicine, Cleveland, OH (J.D.R.)
| | - James D Reynolds
- From Institute for Transformative Molecular Medicine, Case Western Reserve University School of Medicine and University Hospitals Cleveland Medical Center, OH (J.S.S., J.D.R., D.T.H.); Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH (J.S.S., D.T.H.); Harrington Discovery Institute, University Hospitals Cleveland Medical Center, OH (J.S.S., J.D.R.); Department of Anesthesiology and Perioperative Medicine, Case Western Reserve University School of Medicine, Cleveland, OH (J.D.R.)
| | - Douglas T Hess
- From Institute for Transformative Molecular Medicine, Case Western Reserve University School of Medicine and University Hospitals Cleveland Medical Center, OH (J.S.S., J.D.R., D.T.H.); Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, OH (J.S.S., D.T.H.); Harrington Discovery Institute, University Hospitals Cleveland Medical Center, OH (J.S.S., J.D.R.); Department of Anesthesiology and Perioperative Medicine, Case Western Reserve University School of Medicine, Cleveland, OH (J.D.R.)
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6
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Rifkind JM, Mohanty JG, Nagababu E, Salgado MT, Cao Z. Potential Modulation of Vascular Function by Nitric Oxide and Reactive Oxygen Species Released From Erythrocytes. Front Physiol 2018; 9:690. [PMID: 29930515 PMCID: PMC5999795 DOI: 10.3389/fphys.2018.00690] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 05/17/2018] [Indexed: 11/15/2022] Open
Abstract
The primary role for erythrocytes is oxygen transport that requires the reversible binding of oxygen to hemoglobin. There are, however, secondary reactions whereby the erythrocyte can generate reactive oxygen species (ROS) and nitric oxide (NO). ROS such as superoxide anion and hydrogen peroxide are generated by the autoxidation of hemoglobin. NO can be generated when nitrite reacts with hemoglobin forming an HbNO+ intermediate. Both of these reactions are dramatically enhanced under hypoxic conditions. Within the erythrocyte, interactions of NO with hemoglobin and enzymatic reactions that neutralize ROS are expected to prevent the release of any generated NO or ROS. We have, however, demonstrated that partially oxygenated hemoglobin has a distinct conformation that enhances hemoglobin-membrane interactions involving Band 3 protein. Autoxidation of the membrane bound partially oxygenated hemoglobin facilitates the release of ROS from the erythrocyte. NO release is made possible when HbNO+, the hemoglobin nitrite-reduced intermediate, which is not neutralized by hemoglobin, is bound to the membrane and releases NO. Some of the released ROS has been shown to be transferred to the vasculature suggesting that some of the released NO may also be transferred to the vasculature. NO is known to have a major effect on the vasculature regulating vascular dilatation. Erythrocyte generated NO may be important when NO production by the vasculature is impaired. Furthermore, the erythrocyte NO released, may play an important role in regulating vascular function under hypoxic conditions when endothelial eNOS is less active. ROS can react with NO and, can thereby modulate the vascular effects of NO. We have also demonstrated an inflammatory response due to erythrocyte ROS. This reflects the ability of ROS to react with various cellular components affecting cellular function.
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Affiliation(s)
- Joseph M Rifkind
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Joy G Mohanty
- National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Enika Nagababu
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Maria T Salgado
- National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Zeling Cao
- National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
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7
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Orf GS, Saer RG, Niedzwiedzki DM, Zhang H, McIntosh CL, Schultz JW, Mirica LM, Blankenship RE. Evidence for a cysteine-mediated mechanism of excitation energy regulation in a photosynthetic antenna complex. Proc Natl Acad Sci U S A 2016; 113:E4486-93. [PMID: 27335466 PMCID: PMC4978306 DOI: 10.1073/pnas.1603330113] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Light-harvesting antenna complexes not only aid in the capture of solar energy for photosynthesis, but regulate the quantity of transferred energy as well. Light-harvesting regulation is important for protecting reaction center complexes from overexcitation, generation of reactive oxygen species, and metabolic overload. Usually, this regulation is controlled by the association of light-harvesting antennas with accessory quenchers such as carotenoids. One antenna complex, the Fenna-Matthews-Olson (FMO) antenna protein from green sulfur bacteria, completely lacks carotenoids and other known accessory quenchers. Nonetheless, the FMO protein is able to quench energy transfer in aerobic conditions effectively, indicating a previously unidentified type of regulatory mechanism. Through de novo sequencing MS, chemical modification, and mutagenesis, we have pinpointed the source of the quenching action to cysteine residues (Cys49 and Cys353) situated near two low-energy bacteriochlorophylls in the FMO protein from Chlorobaculum tepidum Removal of these cysteines (particularly removal of the completely conserved Cys353) through N-ethylmaleimide modification or mutagenesis to alanine abolishes the aerobic quenching effect. Electrochemical analysis and electron paramagnetic resonance spectra suggest that in aerobic conditions the cysteine thiols are converted to thiyl radicals which then are capable of quenching bacteriochlorophyll excited states through electron transfer photochemistry. This simple mechanism has implications for the design of bio-inspired light-harvesting antennas and the redesign of natural photosynthetic systems.
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Affiliation(s)
- Gregory S Orf
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130; Department of Biology, Washington University in St. Louis, St. Louis, MO 63130; Photosynthetic Antenna Research Center, Washington University in St. Louis, St. Louis, MO 63130
| | - Rafael G Saer
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130; Photosynthetic Antenna Research Center, Washington University in St. Louis, St. Louis, MO 63130
| | - Dariusz M Niedzwiedzki
- Photosynthetic Antenna Research Center, Washington University in St. Louis, St. Louis, MO 63130
| | - Hao Zhang
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130; Photosynthetic Antenna Research Center, Washington University in St. Louis, St. Louis, MO 63130
| | - Chelsea L McIntosh
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130
| | - Jason W Schultz
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130
| | - Liviu M Mirica
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130
| | - Robert E Blankenship
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130; Department of Biology, Washington University in St. Louis, St. Louis, MO 63130; Photosynthetic Antenna Research Center, Washington University in St. Louis, St. Louis, MO 63130
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8
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Rhodes CJ. The Role of ESR Spectroscopy in Advancing Catalytic Science: Some Recent Developments. PROGRESS IN REACTION KINETICS AND MECHANISM 2015. [DOI: 10.3184/146867815x14297237081532] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Recent progress is surveyed in regard to the importance of molecular species containing unpaired electrons in catalytic systems, as revealed using ESR spectroscopy. The review begins with studies of enzymes and their role directly in biological systems, and then discusses investigations of various artificially created catalysts with potential human and environmental significance, including zeolites. Among the specific types of catalytic media considered are those for photocatalysis, water splitting, the degradation of environmental pollutants, hydrocarbon conversions, fuel cells, ionic liquids and sensor devices employing graphene. Studies of muonium-labelled radicals in zeolites are also reviewed, as a means for determining the dynamics of transient radicals in these nanoporous materials.
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9
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Salgado MT, Cao Z, Nagababu E, Mohanty JG, Rifkind JM. Red Blood Cell Membrane-Facilitated Release of Nitrite-Derived Nitric Oxide Bioactivity. Biochemistry 2015; 54:6712-23. [DOI: 10.1021/acs.biochem.5b00643] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Maria T. Salgado
- Molecular Dynamics Section,
National Institute on Aging, National Institutes of Health, 251 Bayview
Boulevard, Baltimore, Maryland 21224, United States
| | - Zeling Cao
- Molecular Dynamics Section,
National Institute on Aging, National Institutes of Health, 251 Bayview
Boulevard, Baltimore, Maryland 21224, United States
| | - Enika Nagababu
- Molecular Dynamics Section,
National Institute on Aging, National Institutes of Health, 251 Bayview
Boulevard, Baltimore, Maryland 21224, United States
| | - Joy G. Mohanty
- Molecular Dynamics Section,
National Institute on Aging, National Institutes of Health, 251 Bayview
Boulevard, Baltimore, Maryland 21224, United States
| | - Joseph M. Rifkind
- Molecular Dynamics Section,
National Institute on Aging, National Institutes of Health, 251 Bayview
Boulevard, Baltimore, Maryland 21224, United States
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10
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Silaghi-Dumitrescu R, Svistunenko DA, Cioloboc D, Bischin C, Scurtu F, Cooper CE. Nitrite binding to globins: linkage isomerism, EPR silence and reductive chemistry. Nitric Oxide 2014; 42:32-9. [PMID: 25172022 PMCID: PMC4256065 DOI: 10.1016/j.niox.2014.08.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Revised: 07/29/2014] [Accepted: 08/18/2014] [Indexed: 12/28/2022]
Abstract
A DFT-derived barrier for nitrite linkage isomerism on heme center is reported. EPR spectra of nitrite adducts show evidence for linkage isomerism. The electronic structure of Fe(III)-nitrite heme is conformation-dependent. Certain conformations are inducive to EPR silence. Fe(II)-nitrite is undetectable on stopped-flow time scales.
The nitrite adducts of globins can potentially bind via O- or N- linkage to the heme iron. We have used EPR (electron paramagnetic resonance) and DFT (density functional theory) to explore these binding modes to myoglobin and hemoglobin. We demonstrate that the nitrite adducts of both globins have detectable EPR signals; we provide an explanation for the difficulty in detecting these EPR features, based on uniaxial state considerations. The EPR and DFT data show that both nitrite linkage isomers can be present at the same time and that the two isomers are readily interconvertible in solution. The millisecond-scale process of nitrite reduction by Hb is investigated in search of the elusive Fe(II)-nitrite adduct.
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Affiliation(s)
- Radu Silaghi-Dumitrescu
- "Babeş-Bolyai" University, 1 Mihail Kogalniceanu str., RO-400084 Cluj-Napoca, Romania; Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, UK.
| | - Dimitri A Svistunenko
- Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, UK
| | - Daniela Cioloboc
- "Babeş-Bolyai" University, 1 Mihail Kogalniceanu str., RO-400084 Cluj-Napoca, Romania
| | - Cristina Bischin
- "Babeş-Bolyai" University, 1 Mihail Kogalniceanu str., RO-400084 Cluj-Napoca, Romania
| | - Florina Scurtu
- "Babeş-Bolyai" University, 1 Mihail Kogalniceanu str., RO-400084 Cluj-Napoca, Romania
| | - Chris E Cooper
- Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, UK
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11
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Affiliation(s)
- Luisa B. Maia
- REQUIMTE/CQFB, Departamento
de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - José J. G. Moura
- REQUIMTE/CQFB, Departamento
de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
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12
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Abstract
An overview is provided of the importance of molecular species containing unpaired electrons in catalytic systems, as revealed using ESR spectroscopy. The review aims to demonstrate the considerable extent of scientific progress that has been made in this broad topic during the past few decades. Studies of catalytically active surfaces, including zeolites, are surveyed, and the detection of radical species, formed as intermediates in their reactions, using matrix isolation and spin-trapping techniques. Radical cation formation in zeolites is discussed, and the employment of muon spin rotation and relaxation techniques to study the mobility of labelled radicals in various porous and catalytic media. Among the specific types of catalytic media considered are those for photocatalysis, water splitting, degradation of environmental pollutants, hydrocarbon conversions, fuel cells and sensor devices employing graphene. The review concludes with recent developments in the study of enzymes and their reactions, using ESR-based methods.
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13
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Abstract
From the perspectives of disease transmission and sterility maintenance, the world's blood supplies are generally safe. However, in multiple clinical settings, red blood cell (RBC) transfusions are associated with adverse cardiovascular events and multiorgan injury. Because ∼85 million units of blood are administered worldwide each year, transfusion-related morbidity and mortality is a major public health concern. Blood undergoes multiple biochemical changes during storage, but the relevance of these changes to unfavorable outcomes is unclear. Banked blood shows reduced levels of S-nitrosohemoglobin (SNO-Hb), which in turn impairs the ability of stored RBCs to effect hypoxic vasodilation. We therefore reasoned that transfusion of SNO-Hb-deficient blood may exacerbate, rather than correct, impairments in tissue oxygenation, and that restoration of SNO-Hb levels would improve transfusion efficacy. Notably in mice, administration of banked RBCs decreased skeletal muscle pO2, but infusion of renitrosylated cells maintained tissue oxygenation. In rats, hemorrhage-induced reductions in muscle pO2 were corrected by SNO-Hb-repleted RBCs, but not by control, stored RBCs. In anemic awake sheep, stored renitrosylated, but not control RBCs, produced sustained improvements in O2 delivery; in anesthetized sheep, decrements in hemodynamic status, renal blood flow, and kidney function incurred following transfusion of banked blood were also prevented by renitrosylation. Collectively, our findings lend support to the idea that transfusions may be causally linked to ischemic events and suggest a simple approach to prevention (i.e., SNO-Hb repletion). If these data are replicated in clinical trials, renitrosylation therapy could have significant therapeutic impact on the care of millions of patients.
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14
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Roche CJ, Cassera MB, Dantsker D, Hirsch RE, Friedman JM. Generating S-nitrosothiols from hemoglobin: mechanisms, conformational dependence, and physiological relevance. J Biol Chem 2013; 288:22408-25. [PMID: 23775069 DOI: 10.1074/jbc.m113.482679] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In vitro, ferrous deoxy-hemes in hemoglobin (Hb) react with nitrite to generate nitric oxide (NO) through a nitrite reductase reaction. In vivo studies indicate Hb with nitrite can be a source of NO bioactivity. The nitrite reductase reaction does not appear to account fully for this activity because free NO is short lived especially within the red blood cell. Thus, the exporting of NO bioactivity both out of the RBC and over a large distance requires an additional mechanism. A nitrite anhydrase (NA) reaction in which N2O3, a potent S-nitrosating agent, is produced through the reaction of NO with ferric heme-bound nitrite has been proposed (Basu, S., Grubina, R., Huang, J., Conradie, J., Huang, Z., Jeffers, A., Jiang, A., He, X., Azarov, I., Seibert, R., Mehta, A., Patel, R., King, S. B., Hogg, N., Ghosh, A., Gladwin, M. T., and Kim-Shapiro, D. B. (2007) Nat. Chem. Biol. 3, 785-794) as a possible mechanism. Legitimate concerns, including physiological relevance and the nature of the mechanism, have been raised concerning the NA reaction. This study addresses these concerns demonstrating NO and nitrite with ferric hemes under near physiological conditions yield an intermediate having the properties of the purported NA heme-bound N2O3 intermediate. The results indicate that ferric heme sites, traditionally viewed as a source of potential toxicity, can be functionally significant, especially for partially oxygenated/partially met-R state Hb that arises from the NO dioxygenation reaction. In the presence of low levels of nitrite and either NO or a suitable reductant such as L-cysteine, these ferric heme sites can function as a generator for the formation of S-nitrosothiols such as S-nitrosoglutathione and, as such, should be considered as a source of RBC-derived and exportable bioactive NO.
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Affiliation(s)
- Camille J Roche
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Abstract
SIGNIFICANCE The physiological mechanism(s) for recognition and removal of red blood cells (RBCs) from circulation after 120 days of its lifespan is not fully understood. Many of the processes thought to be associated with the removal of RBCs involve oxidative stress. We have focused on hemoglobin (Hb) redox reactions, which is the major source of RBC oxidative stress. RECENT ADVANCES The importance of Hb redox reactions have been shown to originate in large parts from the continuous slow autoxidation of Hb producing superoxide and its dramatic increase under hypoxic conditions. In addition, oxidative stress has been shown to be associated with redox reactions that originate from Hb reactions with nitrite and nitric oxide (NO) and the resultant formation of highly toxic peroxynitrite when NO reacts with superoxide released during Hb autoxidation. CRITICAL ISSUES The interaction of Hb, particularly under hypoxic conditions with band 3 of the RBC membrane is critical for the generating the RBC membrane changes that trigger the removal of cells from circulation. These changes include exposure of antigenic sites, increased calcium leakage into the RBC, and the resultant leakage of potassium out of the RBC causing cell shrinkage and impaired deformability. FUTURE DIRECTIONS The need to understand the oxidative damage to specific membrane proteins that result from redox reactions occurring when Hb is bound to the membrane. Proteomic studies that can pinpoint the specific proteins damaged under different conditions will help elucidate the cellular aging processes that result in cells being removed from circulation.
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Affiliation(s)
- Joseph M Rifkind
- Molecular Dynamics Section, National Institute on Aging, Baltimore, MD 21224, USA.
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Car-Parinello molecular dynamics simulations of thionitroxide and S-nitrosothiol in the gas phase, methanol, and water—A theoretical study of S-nitrosylation. Sci China Chem 2012. [DOI: 10.1007/s11426-012-4712-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Owusu BY, Stapley R, Patel RP. Nitric oxide formation versus scavenging: the red blood cell balancing act. J Physiol 2012; 590:4993-5000. [PMID: 22687616 DOI: 10.1113/jphysiol.2012.234906] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Nitric oxide (NO) is a key modulator of vascular homeostasis controlling critical functions related to blood flow, respiration, cell death and proliferation, and protecting the vasculature from pro-inflammatory and coagulative stresses. Inhibition of NO formation, and/or diversion of NO away from its physiological signalling targets lead to dysregulated NO bioavailability, a hallmark of numerous vascular and pulmonary diseases. Current concepts suggest that the balance between NO formation and NO scavenging is critical in disease development, with the corollary being that redressing the balance offers a target for therapeutic intervention. Evidence presented over the last two decades has seen red blood cells (RBCs) and haemoglobin specifically emerge as prominent effectors in this paradigm. In this symposium review article, we discuss recent insights into the mechanisms by which RBCs may modulate the balance between NO-formation and inhibition. We discuss how these mechanisms may become dysfunctional to cause disease, highlight key questions that remain, and discuss the potential impact of these insights on therapeutic opportunities.
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Affiliation(s)
- Benjamin Y Owusu
- Department of Pathology, University of Alabama at Birmingham, 901 19th Street South, BMRII 532, Birmingham, AL 35294, USA
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Kristian KE, Bakac A. Reduction of nitrous acid with a macrocyclic rhodium complex that acts as a functional model of nitrite reductase. Inorg Chem 2012; 51:4877-82. [PMID: 22480334 DOI: 10.1021/ic300597n] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nitrous acid reacts with L(2)(H(2)O)Rh(2+) (L(2) = meso-hexamethylcyclam) in acidic aqueous solutions to generate a strongly absorbing intermediate Int-1 (λ(max) 400 nm, ε = 1200 M(-1) cm(-1)). The reaction follows a mixed second order rate law with k = (6.9 ± 0.3) × 10(4) M(-1) s(-1), independent of [H(+)]. The lack of acid dependence shows that Int-1 is a rhodium(II) complex of HNO(2), most reasonably assigned as L(2)(H(2)O)Rh(HNO(2))(2+). This species is analogous to the early iron and copper intermediates in the reduction of nitrite by nitrite reductases and by deoxyhemoglobin. In the presence of excess L(2)(H(2)O)Rh(2+), the lifetime of Int-1 is about 1 min. It decays to a 1:1 mixture of L(2)(H(2)O)RhNO(2+) and L(2)Rh(H(2)O)(2)(3+) with kinetics that are largely independent of the concentration of excess L(2)(H(2)O)Rh(2+) and of [H(+)] at [H(+)] < 0.03 M. At [H(+)] > 0.03 M, an acid-catalyzed pathway becomes effective, suggesting protonation and dehydration of Int-1 to generate L(2)(H(2)O)RhNO(3+) (Int-2) followed by rapid reduction of Int-2 by excess L(2)(H(2)O)Rh(2+). Int-2, which was generated and characterized independently, is an analog of the electrophilic intermediates in the mechanism of biological reduction of nitrite to (•)NO. Excess nitrite greatly reduces the lifetime of Int-1, which under such conditions decomposes on a millisecond time scale by nitrite-catalyzed disproportionation to yield L(2)(H(2)O)RhNO(2+) and L(2)Rh(III). This reaction provides additional support for the designation of Int-1 as a Rh(II) species. The complex reaction mechanism and the detection of Int-1 demonstrate the ability of inorganic complexes to perform the fundamental chemistry believed to take place in the biological reduction of HNO(2) to NO catalyzed by nitrite reductases or deoxyhemoglobin.
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