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Structure effect of water-soluble iron porphyrins on catalyzing protein tyrosine nitration in the presence of nitrite and hydrogen peroxide. Nitric Oxide 2019; 91:42-51. [PMID: 31351146 DOI: 10.1016/j.niox.2019.07.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 07/17/2019] [Accepted: 07/22/2019] [Indexed: 12/15/2022]
Abstract
Water-soluble iron porphyrins, such as FeTPPS (5,10,15,20-tetrakis (4-sulfonatophenyl) porphyrinato iron (III)), FeTMPyP (5,10,15,20-tetrakis (N-methyl-4'-pyridyl) porphyrinato iron (III) chloride) and FeTBAP (5,10,15,20-tetrakis (4-benzoic acid) porphyrinato iron (III)), are highly active catalysts for peroxynitrite decomposition and thereby have been suggested as therapeutic agent for inflammatory diseases that implicate the involvement of nitrotyrosine formation. Here, we systemically investigated catalytic properties of FeTPPS, FeTMPyP and FeTBAP on protein nitration in the presence of hydrogen peroxide and nitrite. We showed that FeTPPS, FeTBAP and FeTMPyP all exhibited higher peroxidase activity in compared with hemin. As to protein nitration, the catalytic effect of FeTPPS and FeTBAP are effective in the presence of hydrogen peroxide and nitrite, while negligible BSA nitration was observed in the case of FeTMPyP. Moreover, the underlying mechanism of the oxidation of FeTPPS, FeTBAP and FeTMPyP was further studied. Collectively, our results suggest that, compound I and II species are involved in as the key intermediates in FeTMPyP/H2O2 system as similar as those in FeTPPS/H2O2 and FeTBAP/H2O2 system. As compared to weak antioxidants, TPPS and TBAP, however, TMPyP scavenges oxo-Fe (IV) intermediates of FeTMPyP at a faster rate by significant self-degradation; results in the shortest lifetimes of OFeIV-TMPyP and the lowest catalytic activity on oxidizing tyrosine and nitrite; and therefore, attributes to inactivation of FeTMPyP in protein nitration. In addition, association of FeTMPyP to BSA was found weak, while strong binding of FeTPPS and FeTBAP were observed. The weak binding keeps away of target residue of BSA from the center of FeTMPyP where the RNS is generated, which might be attributed as additional factors to the inactivation of FeTMPyP in protein nitration.
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2
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Lin YW. Structure and function of heme proteins regulated by diverse post-translational modifications. Arch Biochem Biophys 2018; 641:1-30. [DOI: 10.1016/j.abb.2018.01.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 01/10/2018] [Accepted: 01/13/2018] [Indexed: 01/08/2023]
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3
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Nilsson ZN, Mandella BL, Sen K, Kekilli D, Hough MA, Moenne-Loccoz P, Strange RW, Andrew CR. Distinguishing Nitro vs Nitrito Coordination in Cytochrome c' Using Vibrational Spectroscopy and Density Functional Theory. Inorg Chem 2017; 56:13205-13213. [PMID: 29053273 PMCID: PMC5677563 DOI: 10.1021/acs.inorgchem.7b01945] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nitrite coordination to heme cofactors is a key step in the anaerobic production of the signaling molecule nitric oxide (NO). An ambidentate ligand, nitrite has the potential to coordinate via the N- (nitro) or O- (nitrito) atoms in a manner that can direct its reactivity. Distinguishing nitro vs nitrito coordination, along with the influence of the surrounding protein, is therefore of particular interest. In this study, we probed Fe(III) heme-nitrite coordination in Alcaligenes xylosoxidans cytochrome c' (AXCP), an NO carrier that excludes anions in its native state but that readily binds nitrite (Kd ∼ 0.5 mM) following a distal Leu16 → Gly mutation to remove distal steric constraints. Room-temperature resonance Raman spectra (407 nm excitation) identify ν(Fe-NO2), δ(ONO), and νs(NO2) nitrite ligand vibrations in solution. Illumination with 351 nm UV light results in photoconversion to {FeNO}6 and {FeNO}7 states, enabling FTIR measurements to distinguish νs(NO2) and νas(NO2) vibrations from differential spectra. Density functional theory calculations highlight the connections between heme environment, nitrite coordination mode, and vibrational properties and confirm that nitrite binds to L16G AXCP exclusively through the N atom. Efforts to obtain the nitrite complex crystal structure were hampered by photochemistry in the X-ray beam. Although low dose crystal structures could be modeled with a mixed nitrite (nitro)/H2O distal population, their photosensitivity and partial occupancy underscores the value of the vibrational approach. Overall, this study sheds light on steric determinants of heme-nitrite binding and provides vibrational benchmarks for future studies of heme protein nitrite reactions.
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Affiliation(s)
- Zach N. Nilsson
- Department of Chemistry and Biochemistry, Eastern Oregon University, La Grande, Oregon 97850, United States
| | - Brian L. Mandella
- Department of Chemistry and Biochemistry, Eastern Oregon University, La Grande, Oregon 97850, United States
| | - Kakali Sen
- School of Biological Sciences, University of Essex, Colchester Essex, CO4 3SQ, United Kingdom
- Scientific Computing Department, STFC Daresbury Laboratory, Warrington, Cheshire WA4 4AD, United Kingdom
| | - Demet Kekilli
- School of Biological Sciences, University of Essex, Colchester Essex, CO4 3SQ, United Kingdom
| | - Michael A Hough
- School of Biological Sciences, University of Essex, Colchester Essex, CO4 3SQ, United Kingdom
| | - Pierre Moenne-Loccoz
- Division of Environmental and Biomolecular Systems, Oregon Health and Science University, Portland, Oregon 97239, United States
| | - Richard W. Strange
- School of Biological Sciences, University of Essex, Colchester Essex, CO4 3SQ, United Kingdom
| | - Colin R. Andrew
- Department of Chemistry and Biochemistry, Eastern Oregon University, La Grande, Oregon 97850, United States
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Samuni A, Maimon E, Goldstein S. Mechanism of HRP-catalyzed nitrite oxidation by H 2O 2 revisited: Effect of nitroxides on enzyme inactivation and its catalytic activity. Free Radic Biol Med 2017; 108:832-839. [PMID: 28495446 DOI: 10.1016/j.freeradbiomed.2017.05.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 05/01/2017] [Accepted: 05/07/2017] [Indexed: 10/19/2022]
Abstract
The peroxidative activity of horseradish peroxidase (HRP) undergoes progressive inactivation while catalyzing the oxidation of nitrite by H2O2. The extent of inactivation increases as the pH increases, [nitrite] decreases or [H2O2] increases, and is accompanied by a loss of the Soret peak of HRP along with yellow-greenish coloration of the solution. HRP-catalyzed nitrite oxidation by H2O2 involves not only the formation of compounds I and II as transient heme species, but also compound III, all of which in turn, oxidize nitrite yielding •NO2. The rate constant of nitrite oxidation by compound III is at least 10-fold higher than that by compound II, which is also reducible by •NO2 where its reduction by nitrite is the rate-determining step of the catalytic cycle. The extent of the loss of the Soret peak of HRP is lower than the loss of its peroxidative activity implying that deterioration of the heme moiety leading to iron release only partially contributes toward heme inactivation. Cyclic stable nitroxide radicals, such as 2,2,6,6-tetramethyl-piperidine-N-oxyl (TPO), 4-OH-TPO and 4-NH2-TPO at µM concentrations detoxify •NO2 thus protecting HRP against inactivation mediated by this radical. Hence, HRP inactivation proceeds via nitration of the porphyrin ring most probably through compound I reaction with •NO2, which partially leads to deterioration of the heme moiety. The nitroxide acts catalytically since its oxidation by •NO2 yields the respective oxoammonium cation, which is readily reduced back to the nitroxide by H2O2, superoxide ion radical, and nitrite. In addition, the nitroxide catalytically inhibits tyrosine nitration mediated by HRP/H2O2/nitrite reactions system as it efficiently competes with tyrosyl radical for •NO2. The inhibition by nitroxides of tyrosine nitration is demonstrated also in the case of microperoxidase (MP-11) and cytochrome c revealing an additional role played by nitroxide antioxidants.
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Affiliation(s)
- Amram Samuni
- Institute of Medical Research Israel-Canada, Medical School, The Hebrew University of Jerusalem, Jerusalem 91120, Israel
| | - Eric Maimon
- Nuclear Research Centre Negev, Be'er Sheva, Israel
| | - Sara Goldstein
- Institute of Chemistry, The Accelerator Laboratory, the Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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Ioannou A, Pinakoulaki E. Probing nitrite coordination in horseradish peroxidase by resonance Raman spectroscopy: Detection of two binding sites. J Inorg Biochem 2017; 169:79-85. [PMID: 28160625 DOI: 10.1016/j.jinorgbio.2017.01.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 01/04/2017] [Accepted: 01/20/2017] [Indexed: 11/15/2022]
Abstract
Nitrite is a powerful oxidant that affects the activity of peroxidases towards various substrates and leads to heme macrocycle modifications in members of the peroxidase family, such as the horseradish peroxidase (HRP). We have applied resonance Raman spectroscopy to investigate the structural properties of the species formed in the reaction of NO2- with the ferric form of HRP. Our data demonstrate that the heme nitrovinyl group is partially formed at near neutral pH, without coordination of NO2- to the heme Fe. Nitrite coordinates to the heme Fe at acidic pH in the nitro binding mode, characterized by the detection of the ν(Fe-NO2) at 563cm-1, δ(FeNO2) at 822cm-1 and νsym(NO2) at 1272cm-1. The sensitivity of the vibrations of the heme Fe-nitro complex to H/D exchange indicates H-bonding interaction of the heme-bound ligand with the distal environment that determines the NO2- binding mode. A model describing the different modes of NO2- binding in HRP is presented.
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Affiliation(s)
- Androulla Ioannou
- Department of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus
| | - Eftychia Pinakoulaki
- Department of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus.
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6
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Ioannou A, Lambrou A, Daskalakis V, Pinakoulaki E. Coupling of helix E-F motion with the O-nitrito and 2-nitrovinyl coordination in myoglobin. Biophys Chem 2017; 221:10-16. [DOI: 10.1016/j.bpc.2016.11.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 11/15/2016] [Accepted: 11/23/2016] [Indexed: 10/20/2022]
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7
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Lin YW. The broad diversity of heme-protein cross-links: An overview. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:844-59. [DOI: 10.1016/j.bbapap.2015.04.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 03/26/2015] [Accepted: 04/17/2015] [Indexed: 12/30/2022]
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Urarte E, Asensio AC, Tellechea E, Pires L, Moran JF. Evaluation of the anti-nitrative effect of plant antioxidants using a cowpea Fe-superoxide dismutase as a target. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2014; 83:356-364. [PMID: 25221924 DOI: 10.1016/j.plaphy.2014.08.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 08/24/2014] [Indexed: 06/03/2023]
Abstract
Nitric oxide cytotoxicity arises from its rapid conversion to peroxynitrite (ONOO(-)) in the presence of superoxide, provoking functional changes in proteins by nitration of tyrosine residues. The physiological significance of this post-translational modification is associated to tissue injury in animals, but has not been yet clarified in plants. The objective of this study was to establish new approaches that could help to understand ONOO(-) reactivity in plants. A recombinant Fe-superoxide dismutase from cowpea (Vigna unguiculata (L.) Walp.), rVuFeSOD, was the target of the ONOO(-)-generator SIN-1, and the anti-nitrative effect of plant antioxidants and haemoglobins was tested in vitro. Nitration on rVuFeSOD was evaluated immunochemically or as the loss of its enzymatic activity. This assay proved to be useful to test a variety of plant compounds for anti-nitrative capacity. Experimental data confirmed that rice (Oryza sativa L.) haemoglobin-1 (rOsHbI) and cowpea leghaemoglobin-2 exerted a protective function against ONOO(-) by diminishing nitration on rVuFeSOD. Both plant haemoglobins were nitrated by SIN-1. The chelator desferrioxamine suppressed nitration in rOsHbI, indicating that Fe plays a key role in the reaction. The removal of the haem moiety in rOsHbI importantly suppressed nitration, evidencing that this reaction may be self-catalyzed. Among small antioxidants, ascorbate remarkably decreased nitration in all tests. The phenolic compounds caffeic acid, gallic acid, pyrogallol, 4-hydroxybenzoic acid and the flavonoid gossypin also diminished tyrosine nitration and protected rVuFeSOD to different extents. It is concluded that small plant antioxidants, especially ascorbate, and haemoglobins may well play key roles in ONOO(-) homeostasis in vivo.
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Affiliation(s)
- Estibaliz Urarte
- Institute of Agrobiotechnology, IdAB-CSIC-Public University of Navarre-Government of Navarre, Avda. Pamplona 123, E-31192, Mutilva, Navarre, Spain
| | - Aaron C Asensio
- CEMITEC, Polígono Mocholí, Plaza Cein 4, E-31110, Noain, Navarre, Spain
| | - Edurne Tellechea
- CEMITEC, Polígono Mocholí, Plaza Cein 4, E-31110, Noain, Navarre, Spain
| | - Laura Pires
- Institute of Agrobiotechnology, IdAB-CSIC-Public University of Navarre-Government of Navarre, Avda. Pamplona 123, E-31192, Mutilva, Navarre, Spain
| | - Jose F Moran
- Institute of Agrobiotechnology, IdAB-CSIC-Public University of Navarre-Government of Navarre, Avda. Pamplona 123, E-31192, Mutilva, Navarre, Spain.
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9
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Horseradish peroxidase inactivation: heme destruction and influence of polyethylene glycol. Sci Rep 2013; 3:3126. [PMID: 24185130 PMCID: PMC3816284 DOI: 10.1038/srep03126] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Accepted: 10/15/2013] [Indexed: 11/26/2022] Open
Abstract
Horseradish peroxidase (HRP) mediates efficient conversion of many phenolic contaminants and thus has potential applications for pollution control. Such potentially important applications suffer however from the fact that the enzyme becomes quickly inactivated during phenol oxidation and polymerization. The work here provides the first experimental data of heme consumption and iron releases to support the hypothesis that HRP is inactivated by heme destruction. Product of heme destruction is identified using liquid chromatography with mass spectrometry. The heme macrocycle destruction involving deprivation of the heme iron and oxidation of the 4-vinyl group in heme occurs as a result of the reaction. We also demonstrated that heme consumption and iron releases resulting from HRP destruction are largely reduced in the presence of polyethylene glycol (PEG), providing the first evidence to indicate that heme destruction is effectively suppressed by co-dissolved PEG. These findings advance a better understanding of the mechanisms of HRP inactivation.
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10
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Leghemoglobin green derivatives with nitrated hemes evidence production of highly reactive nitrogen species during aging of legume nodules. Proc Natl Acad Sci U S A 2012; 109:2660-5. [PMID: 22308405 DOI: 10.1073/pnas.1116559109] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Globins constitute a superfamily of proteins widespread in all kingdoms of life, where they fulfill multiple functions, such as efficient O(2) transport and modulation of nitric oxide bioactivity. In plants, the most abundant Hbs are the symbiotic leghemoglobins (Lbs) that scavenge O(2) and facilitate its diffusion to the N(2)-fixing bacteroids in nodules. The biosynthesis of Lbs during nodule formation has been studied in detail, whereas little is known about the green derivatives of Lbs generated during nodule senescence. Here we characterize modified forms of Lbs, termed Lba(m), Lbc(m), and Lbd(m), of soybean nodules. These green Lbs have identical globins to the parent red Lbs but their hemes are nitrated. By combining UV-visible, MS, NMR, and resonance Raman spectroscopies with reconstitution experiments of the apoprotein with protoheme or mesoheme, we show that the nitro group is on the 4-vinyl. In vitro nitration of Lba with excess nitrite produced several isomers of nitrated heme, one of which is identical to those found in vivo. The use of antioxidants, metal chelators, and heme ligands reveals that nitration is contingent upon the binding of nitrite to heme Fe, and that the reactive nitrogen species involved derives from nitrous acid and is most probably the nitronium cation. The identification of these green Lbs provides conclusive evidence that highly oxidizing and nitrating species are produced in nodules leading to nitrosative stress. These findings are consistent with a previous report showing that the modified Lbs are more abundant in senescing nodules and have aberrant O(2) binding.
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Yi J, Richter-Addo GB. Unveiling the three-dimensional structure of the green pigment of nitrite-cured meat. Chem Commun (Camb) 2012; 48:4172-4. [DOI: 10.1039/c2cc31065a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Peng D, Ogura H, Zhu W, Ma LH, Evans JP, Ortiz de Montellano PR, La Mar GN. Coupling of the distal hydrogen bond network to the exogenous ligand in substrate-bound, resting state human heme oxygenase. Biochemistry 2009; 48:11231-42. [PMID: 19842713 DOI: 10.1021/bi901216s] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mammalian heme oxygenase (HO) possesses catalytically implicated distal ordered water molecules within an extended H-bond network, with one of the ordered water molecules (#1) providing a bridge between the iron-coordinated ligand and the catalytically critical Asp140, that, in turn, serves as an acceptor for the Tyr58 OH H-bond. The degree of H-bonding by the ligated water molecule and the coupling of this water molecule to the H-bond network are of current interest and are herein investigated by (1)H NMR. Two-dimensional NMR allowed sufficient assignments to provide both the H-bond strength and hyperfine shifts, the latter of which were used to quantify the magnetic anisotropy in both the ferric high-spin aquo and low-spin hydroxo complexes. The anisotropy in the aquo complex indicates that the H-bond donation to water #1 is marginally stronger than in a bacterial HO, while the anisotropy for the hydroxo complex reveals a conventional (d(xz), d(yz))(1) ground state indicative of only moderate to weak H-bond acceptance by the ligated hydroxide. Mapping out the changes of the H-bond strengths in the network during the ligated water --> hydroxide conversion by correcting for the effects of magnetic anisotropy reveals a very substantial change in H-bond strength for Tyr58 OH and lesser effects on nearby H-bonds. The effect of pH on the H-bonding network in human HO is much larger and transmitted much further from the iron than in a pathogenic bacterial HO. The implications for the HO mechanism of the H-bond of Tyr58 to Asp140 are discussed.
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Affiliation(s)
- Dungeng Peng
- Department of Chemistry, University of California, Davis, California 95616, USA
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13
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Badyal SK, Eaton G, Mistry S, Pipirou Z, Basran J, Metcalfe CL, Gumiero A, Handa S, Moody PCE, Raven EL. Evidence for heme oxygenase activity in a heme peroxidase. Biochemistry 2009; 48:4738-46. [PMID: 19309109 DOI: 10.1021/bi900118j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The heme peroxidase and heme oxygenase enzymes share a common heme prosthetic group but catalyze fundamentally different reactions, the first being H(2)O(2)-dependent oxidation of substrate using an oxidized Compound I intermediate, and the second O(2)-dependent degradation of heme. It has been proposed that these enzymes utilize a common reaction intermediate, a ferric hydroperoxide species, that sits at a crossroads in the mechanism and beyond which there are two mutually exclusive mechanistic pathways. Here, we present evidence to support this proposal in a heme peroxidase. Hence, we describe kinetic data for a variant of ascorbate peroxidase (W41A) which reacts slowly with tert-butyl hydroperoxide and does not form the usual peroxidase Compound I intermediate; instead, structural data show that a product is formed in which the heme has been cleaved at the alpha-meso position, analogous to the heme oxygenase mechanism. We interpret this to mean that the Compound I (peroxidase) pathway is shut down, so that instead the reaction intermediate diverts through the alternative (heme oxygenase) route. A mechanism for formation of the product is proposed and discussed in the light of what is known about the heme oxygenase reaction mechanism.
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Affiliation(s)
- Sandip K Badyal
- Department of Chemistry, Henry Wellcome Building, University of Leicester, University Road, Leicester LE1 7RH, UK
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Baer BR, DeLisle RK, Allen A. Benzylic Oxidation of Gemfibrozil-1-O-β-Glucuronide by P450 2C8 Leads to Heme Alkylation and Irreversible Inhibition. Chem Res Toxicol 2009; 22:1298-309. [DOI: 10.1021/tx900105n] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Brian R. Baer
- Department of Drug Metabolism, Array Biopharma Inc., 3200 Walnut Street, Boulder, Colorado 80301
| | - Robert Kirk DeLisle
- Department of Drug Metabolism, Array Biopharma Inc., 3200 Walnut Street, Boulder, Colorado 80301
| | - Andrew Allen
- Department of Drug Metabolism, Array Biopharma Inc., 3200 Walnut Street, Boulder, Colorado 80301
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15
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Ogura H, Evans JP, Peng D, Satterlee JD, Ortiz de Montellano PR, La Mar GN. The orbital ground state of the azide-substrate complex of human heme oxygenase is an indicator of distal H-bonding: implications for the enzyme mechanism. Biochemistry 2009; 48:3127-37. [PMID: 19243105 DOI: 10.1021/bi802360g] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The active site electronic structure of the azide complex of substrate-bound human heme oxygenase 1 (hHO) has been investigated by (1)H NMR spectroscopy to shed light on the orbital/spin ground state as an indicator of the unique distal pocket environment of the enzyme. Two-dimensional (1)H NMR assignments of the substrate and substrate-contact residue signals reveal a pattern of substrate methyl contact shifts that places the lone iron pi-spin in the d(xz) orbital, rather than the d(yz) orbital found in the cyanide complex. Comparison of iron spin relaxivity, magnetic anisotropy, and magnetic susceptibilities argues for a low-spin, (d(xy))(2)(d(yz),d(xz))(3), ground state in both azide and cyanide complexes. The switch from singly occupied d(yz) for the cyanide to d(xz) for the azide complex of hHO is shown to be consistent with the orbital hole determined by the azide pi-plane in the latter complex, which is approximately 90 degrees in-plane rotated from that of the imidazole pi-plane. The induction of the altered orbital ground state in the azide relative to the cyanide hHO complex, as well as the mean low-field bias of methyl hyperfine shifts and their paramagnetic relaxivity relative to those in globins, indicates that azide exerts a stronger ligand field in hHO than in the globins, or that the distal H-bonding to azide is weaker in hHO than in globins. The Asp140 --> Ala hHO mutant that abolishes activity retains the unusual WT azide complex spin/orbital ground state. The relevance of our findings for other HO complexes and the HO mechanism is discussed.
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Affiliation(s)
- Hiroshi Ogura
- Department of Chemistry, University of California, Davis, California 95616, USA
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16
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Ortiz de Montellano PR. Mechanism and Role of Covalent Heme Binding in the CYP4 Family of P450 Enzymes and the Mammalian Peroxidases. Drug Metab Rev 2008; 40:405-26. [DOI: 10.1080/03602530802186439] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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17
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Roth JP, Cramer CJ. Direct Examination of H2O2 Activation by a Heme Peroxidase. J Am Chem Soc 2008; 130:7802-3. [DOI: 10.1021/ja802098c] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Justine P. Roth
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore Maryland 21218, and Department of Chemistry and Research Computing Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55410
| | - Christopher J. Cramer
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore Maryland 21218, and Department of Chemistry and Research Computing Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55410
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18
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Sicking W, Korth HG, de Groot H, Sustmann R. On the functional role of a water molecule in clade 3 catalases: a proposal for the mechanism by which NADPH prevents the formation of compound II. J Am Chem Soc 2008; 130:7345-56. [PMID: 18479132 DOI: 10.1021/ja077787e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
X-ray structures of the 13 different monofunctional heme catalases published to date were scrutinized in order to gain insight in the mechanism by which NADPH in Clade 3 catalases may protect the reactive ferryloxo intermediate Compound I (Cpd I; por (*+)Fe (IV)O) against deactivation to the catalytically inactive intermediate Compound II (Cpd II; porFe (IV)O). Striking similarities in the molecular network of the protein subunits encompassing the heme center and the surface-bound NADPH were found for all of the Clade 3 catalases. Unique features in this region are the presence of a water molecule (W1) adjacent to the 4-vinyl group of heme and a serine residue or a second water molecule hydrogen-bonded to both W1 and the carbonyl group of a threonine-proline linkage, with the proline in van der Waals contact with the dihydronicotinamide group of NADPH. A mechanism is proposed in which a hydroxyl anion released from W1 undergoes reversible nucleophilic addition to the terminal carbon of the 4-vinyl group of Cpd I, thereby producing a neutral porphyrin pi-radical ferryloxo (HO-por (*)Fe (IV)O) species of reduced reactivity. This structure is suggested to be the elusive Cpd II' intermediate proposed in previous studies. An accompanying proton-shifting process along the hydrogen-bonded network is believed to facilitate the NADPH-mediated reduction of Cpd I to ferricatalase and to serve as a funnel for electron transfer from NADPH to the heme center to restore the catalase Fe (III) resting state. The proposed reaction paths were fully supported as chemically reasonable and energetically feasible by means of density functional theory calculations at the (U)B3LYP/6-31G* level. A particularly attractive feature of the present mechanism is that the previously discussed formation of protein-derived radicals is avoided.
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Affiliation(s)
- Willi Sicking
- Institut für Organische Chemie, Universität Duisburg-Essen, 45117 Essen, Germany
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Chen H, Moreau Y, Derat E, Shaik S. Quantum Mechanical/Molecular Mechanical Study of Mechanisms of Heme Degradation by the Enzyme Heme Oxygenase: The Strategic Function of the Water Cluster. J Am Chem Soc 2008; 130:1953-65. [DOI: 10.1021/ja076679p] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Hui Chen
- Department of Organic Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel
| | - Yohann Moreau
- Department of Organic Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel
| | - Etienne Derat
- Department of Organic Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel
| | - Sason Shaik
- Department of Organic Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel
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Huang L, Ortiz de Montellano PR. Arthromyces ramosus peroxidase produces two chlorinating species. Biochem Biophys Res Commun 2007; 355:581-6. [PMID: 17303078 PMCID: PMC1852486 DOI: 10.1016/j.bbrc.2007.02.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Accepted: 02/05/2007] [Indexed: 10/23/2022]
Abstract
We previously reported that the hemes of horseradish peroxidase (HRP) and Arthromyces ramosus peroxidase (ARP) undergo vinyl and meso-carbon modifications when the enzymes oxidize chloride ion. Here we demonstrate for ARP that, although both modifications exhibit the same pH profile with an optimum at approximately pH 4.0, monochlorodimedone suppresses the vinyl but not meso-carbon modifications. Furthermore, meso-chlorination occurs when ARP reacts with exogenous HOCl, implicating an Fe(III)-O-Cl intermediate in the reaction. These results establish that (a) the chloro species involved in meso-modification differs from that which reacts with the vinyl groups, (b) equilibration of the vinyl modifying species (HOCl) into the medium occurs more rapidly than vinyl group modification, and (c) the oxidation of chloride by ARP produces two reactive species: HOCl, which adds to the heme vinyl but not meso-positions, and a distinct second species that adds to the meso-carbon.
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Affiliation(s)
| | - Paul R. Ortiz de Montellano
- To whom editorial correspondence should be addressed: Dr. Paul Ortiz de Montellano, University of California, Genentech Hall N572D, 600 16 Street, San Francisco, CA 94158-2517, TEL: (415) 476-2903, FAX: (415) 502-4728, e-mail:
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