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Shumayrikh NM, Warren JJ, Bennet AJ, Sen D. A heme•DNAzyme activated by hydrogen peroxide catalytically oxidizes thioethers by direct oxygen atom transfer rather than by a Compound I-like intermediate. Nucleic Acids Res 2021; 49:1803-1815. [PMID: 33476369 PMCID: PMC7913675 DOI: 10.1093/nar/gkab007] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 12/31/2020] [Accepted: 01/04/2021] [Indexed: 12/21/2022] Open
Abstract
Hemin [Fe(III)-protoporphyrin IX] is known to bind tightly to single-stranded DNA and RNA molecules that fold into G-quadruplexes (GQ). Such complexes are strongly activated for oxidative catalysis. These heme•DNAzymes and ribozymes have found broad utility in bioanalytical and medicinal chemistry and have also been shown to occur within living cells. However, how a GQ is able to activate hemin is poorly understood. Herein, we report fast kinetic measurements (using stopped-flow UV-vis spectrophotometry) to identify the H2O2-generated activated heme species within a heme•DNAzyme that is active for the oxidation of a thioether substrate, dibenzothiophene (DBT). Singular value decomposition and global fitting analysis was used to analyze the kinetic data, with the results being consistent with the heme•DNAzyme's DBT oxidation being catalyzed by the initial Fe(III)heme-H2O2 complex. Such a complex has been predicted computationally to be a powerful oxidant for thioether substrates. In the heme•DNAzyme, the DNA GQ enhances both the kinetics of formation of the active intermediate as well as the oxidation step of DBT by the active intermediate. We show, using both stopped flow spectrophotometry and EPR measurements, that a classic Compound I is not observable during the catalytic cycle for thioether sulfoxidation.
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Affiliation(s)
- Nisreen M Shumayrikh
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Jeffrey J Warren
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Andrew J Bennet
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Dipankar Sen
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
- Department of Molecular Biology & Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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2
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Tsai AL, Berka V, Martin E, Olson JS. A "sliding scale rule" for selectivity among NO, CO, and O₂ by heme protein sensors. Biochemistry 2011; 51:172-86. [PMID: 22111978 DOI: 10.1021/bi2015629] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Selectivity among NO, CO, and O₂ is crucial for the physiological function of most heme proteins. Although there is a million-fold variation in equilibrium dissociation constants (K(D)), the ratios for NO:CO:O₂ binding stay roughly the same, 1:~10(3):~10(6), when the proximal ligand is a histidine and the distal site is apolar. For these proteins, there is a "sliding scale rule" for plots of log(K(D)) versus ligand type that allows predictions of K(D) values if one or two are missing. The predicted K(D) for binding of O₂to Ns H-NOX coincides with the value determined experimentally at high pressures. Active site hydrogen bond donors break the rule and selectively increase O₂ affinity with little effect on CO and NO binding. Strong field proximal ligands such as thiolate, tyrosinate, and imidazolate exert a "leveling" effect on ligand binding affinity. The reported picomolar K(D) for binding of NO to sGC deviates even more dramatically from the sliding scale rule, showing a NO:CO K(D) ratio of 1:~10(8). This deviation is explained by a complex, multistep process, in which an initial low-affinity hexacoordinate NO complex with a measured K(D) of ≈54 nM, matching that predicted from the sliding scale rule, is formed initially and then is converted to a high-affinity pentacoordinate complex. This multistep six-coordinate to five-coordinate mechanism appears to be common to all NO sensors that exclude O₂ binding to capture a lower level of cellular NO and prevent its consumption by dioxygenation.
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Affiliation(s)
- Ah-Lim Tsai
- Division of Hematology, Internal Medicine, University of Texas Medical School at Houston, Houston, Texas 77030, United States.
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3
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Gil‐Rodríguez P, Ferreira‐Batista C, Vázquez‐Duhalt R, Valderrama B. A Novel Heme Peroxidase fromRaphanus sativusIntrinsically Resistant to Hydrogen Peroxide. Eng Life Sci 2008. [DOI: 10.1002/elsc.200700073] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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4
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Yeh HC, Hsu PY, Tsai AL, Wang LH. Spectroscopic characterization of the oxyferrous complex of prostacyclin synthase in solution and in trapped sol-gel matrix. FEBS J 2008; 275:2305-14. [PMID: 18397321 DOI: 10.1111/j.1742-4658.2008.06385.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Prostacyclin synthase (PGIS) is a member of the cytochrome P450 family in which the oxyferrous complexes are generally labile in the absence of substrate. At 4 degrees C, the on-rate constants and off-rate constants of oxygen binding to PGIS in solution are 5.9 x 10(5) m(-1).s(-1) and 29 s(-1), respectively. The oxyferrous complex decays to a ferric form at a rate of 12 s(-1). We report, for the first time, a stable oxyferrous complex of PGIS in a transparent sol-gel monolith. The encapsulated ferric PGIS retained the same spectroscopic features as in solution. The binding capabilities of the encapsulated PGIS were demonstrated by spectral changes upon the addition of O-based, N-based and C-based ligands. The peroxidase activity of PGIS in sol-gel was three orders of magnitude slower than that in solution owing to the restricted diffusion of the substrate in sol-gel. The oxyferrous complex in sol-gel was observable for 24 h at room temperature and displayed a much red-shifted Soret peak. Stabilization of the ferrous-carbon monoxide complex in sol-gel was observed as an enrichment of the 450-nm species over the 420-nm species. This result suggests that the sol-gel method may be applied to other P450s to generate a stable intermediate in the di-oxygen activation.
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Affiliation(s)
- Hui-Chun Yeh
- Division of Hematology, Department of Internal Medicine, University of Texas Health Science Center, Houston, TX 77030, USA
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5
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Denisov IG, Dawson JH, Hager LP, Sligar SG. The ferric-hydroperoxo complex of chloroperoxidase. Biochem Biophys Res Commun 2007; 363:954-8. [PMID: 17920039 DOI: 10.1016/j.bbrc.2007.09.085] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2007] [Accepted: 09/19/2007] [Indexed: 10/22/2022]
Abstract
The hydroperoxo-ferric complex, or Compound 0 (Cpd 0), is an unstable transient intermediate common for oxygen activating heme enzymes such as the cytochromes P450, nitric oxide synthases, and heme oxygenases, as well as the peroxidases and catalases which utilize hydrogen peroxide as a source of oxygen and reducing equivalents. Detailed understanding of the mechanism of oxygen activation and formation of the higher valent catalytically active intermediates in heme enzyme catalysis requires the structural and spectroscopic characterization of this immediate precursor, Cpd 0. Using the method of cryoradiolytic reduction of the oxy-ferrous heme complex, we have prepared and characterized hydroperoxo-ferric complex in chloroperoxidase (CPO) and compared this to the same intermediate generated in cytochrome P450 CYP101. Optical absorption spectrum of Cpd 0 in CPO has a Soret band at 449 nm and poorly resolved alpha, beta bands at 576 and 546 nm.
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Affiliation(s)
- Ilia G Denisov
- Department of Biochemistry, 116 Morrill Hall, University of Illinois, 505 South Goodwin Avenue, Urbana, IL 61801, USA
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6
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Brzović PS, Dunn MF. Rapid-scanning stopped-flow spectrophotometry. METHODS OF BIOCHEMICAL ANALYSIS 2006; 37:191-273. [PMID: 8309367 DOI: 10.1002/9780470110584.ch5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- P S Brzović
- Department of Biochemistry, University of California, Riverside
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7
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Terner J, Palaniappan V, Gold A, Weiss R, Fitzgerald MM, Sullivan AM, Hosten CM. Resonance Raman spectroscopy of oxoiron(IV) porphyrin π-cation radical and oxoiron(IV) hemes in peroxidase intermediates. J Inorg Biochem 2006; 100:480-501. [PMID: 16513173 DOI: 10.1016/j.jinorgbio.2006.01.008] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Accepted: 01/04/2006] [Indexed: 11/15/2022]
Abstract
The catalytic cycle intermediates of heme peroxidases, known as compounds I and II, have been of long standing interest as models for intermediates of heme proteins, such as the terminal oxidases and cytochrome P450 enzymes, and for non-heme iron enzymes as well. Reports of resonance Raman signals for compound I intermediates of the oxo-iron(IV) porphyrin pi-cation radical type have been sometimes contradictory due to complications arising from photolability, causing compound I signals to appear similar to those of compound II or other forms. However, studies of synthetic systems indicated that protein based compound I intermediates of the oxoiron(IV) porphyrin pi-cation radical type should exhibit vibrational signatures that are different from the non-radical forms. The compound I intermediates of horseradish peroxidase (HRP), and chloroperoxidase (CPO) from Caldariomyces fumago do in fact exhibit unique and characteristic vibrational spectra. The nature of the putative oxoiron(IV) bond in peroxidase intermediates has been under discussion in the recent literature, with suggestions that the Fe(IV)O unit might be better described as Fe(IV)-OH. The generally low Fe(IV)O stretching frequencies observed for proteins have been difficult to mimic in synthetic ferryl porphyrins via electron donation from trans axial ligands alone. Resonance Raman studies of iron-oxygen vibrations within protein species that are sensitive to pH, deuteration, and solvent oxygen exchange, indicate that hydrogen bonding to the oxoiron(IV) group within the protein environment contributes to substantial lowering of Fe(IV)O frequencies relative to those of synthetic model compounds.
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Affiliation(s)
- James Terner
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284-2006, USA.
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8
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Sudhamsu J, Crane BR. Structure and reactivity of a thermostable prokaryotic nitric-oxide synthase that forms a long-lived oxy-heme complex. J Biol Chem 2006; 281:9623-32. [PMID: 16407211 DOI: 10.1074/jbc.m510062200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In an effort to generate more stable reaction intermediates involved in substrate oxidation by nitric-oxide synthases (NOSs), we have cloned, expressed, and characterized a thermostable NOS homolog from the thermophilic bacterium Geobacillus stearothermophilus (gsNOS). As expected, gsNOS forms nitric oxide (NO) from l-arginine via the stable intermediate N-hydroxy l-arginine (NOHA). The addition of oxygen to ferrous gsNOS results in long-lived heme-oxy complexes in the presence (Soret peak 427 nm) and absence (Soret peak 413 nm) of substrates l-arginine and NOHA. The substrate-induced red shift correlates with hydrogen bonding between substrate and heme-bound oxygen resulting in conversion to a ferric heme-superoxy species. In single turnover experiments with NOHA, NO forms only in the presence of H(4)B. The crystal structure of gsNOS at 3.2 AA of resolution reveals great similarity to other known bacterial NOS structures, with the exception of differences in the distal heme pocket, close to the oxygen binding site. In particular, a Lys-356 (Bacillus subtilis NOS) to Arg-365 (gsNOS) substitution alters the conformation of a conserved Asp carboxylate, resulting in movement of an Ile residue toward the heme. Thus, a more constrained heme pocket may slow ligand dissociation and increase the lifetime of heme-bound oxygen to seconds at 4 degrees C. Similarly, the ferric-heme NO complex is also stabilized in gsNOS. The slow kinetics of gsNOS offer promise for studying downstream intermediates involved in substrate oxidation.
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Affiliation(s)
- Jawahar Sudhamsu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
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9
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Park JB, Clark DS. Deactivation mechanisms of chloroperoxidase during biotransformations. Biotechnol Bioeng 2006; 93:1190-5. [PMID: 16425305 DOI: 10.1002/bit.20825] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Inactivation mechanisms of chloroperoxidase (CPO) from Caldariomyces fumago have been investigated with the aim of improving the practical utility of CPO for hydrocarbon oxidation. Deactivation studies in the presence of oxidants (i.e., hydrogen peroxide and t-butyl hydroperoxide) indicated that CPO lost oxidation activity toward hydrocarbon substrates during dismutation of hydrogen peroxide. The loss of enzyme activity was accompanied by the apparent destruction of the heme rather than aggregation or denaturation of the apo-protein. The decrease of enzyme activity was significantly retarded by adding the radical scavenger t-butyl alcohol at pH 4.1, or by optimizing the reaction pH. CPO retained greatest oxidation activity at pH 5-6, which may produce a more favorable ionization state of the key amino acid (Glu-183) and thus reduce radical formation. As a result of higher activity at pH 5-6, the total turnover numbers (TTN, defined as the amount of product produced over the catalytic lifetime of the enzyme) for the oxidation of toluene and o-, m-, p-xylenes in substrate/aqueous emulsion systems ranged from ca. 10% to 110% higher at pH 5.5 (20,000 to 45,000 mol product/mol enzyme) compared to pH 4.1. Furthermore, TTNs of CPO increased with increasing turnover frequencies, indicating that higher activity toward reducing substrates reduces radical formation and stabilizes CPO toward inactivation by H(2)O(2). These findings demonstrate the important relationship between CPO stability and activity, and illustrate that large improvements in CPO activity and stability can be achieved through solvent engineering.
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Affiliation(s)
- Jin-Byung Park
- Department of Chemical Engineering, University of California, Berkeley, 94720, USA
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10
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Jantschko W, Furtmüller PG, Zederbauer M, Jakopitsch C, Obinger C. Kinetics of oxygen binding to ferrous myeloperoxidase. Arch Biochem Biophys 2004; 426:91-7. [PMID: 15130787 DOI: 10.1016/j.abb.2004.03.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2004] [Revised: 03/18/2004] [Indexed: 11/28/2022]
Abstract
Myeloperoxidase (MPO), which is involved in host defence and inflammation, is a unique peroxidase in having a globin-like standard reduction potential of the ferric/ferrous couple. Intravacuolar and exogenous MPO released from stimulated neutrophils has been shown to exist in the oxyferrous form, called compound III. To investigate the reactivity of ferrous MPO with molecular oxygen, a stopped-flow kinetic analysis was performed. In the absence of dioxygen, ferrous MPO decays to ferric MPO (0.04 s(-1) at pH 8 versus 1.4 s(-1) at pH 5). At pH 7.0 and 25 degrees C, compound III formation (i.e., binding of dioxygen to ferrous MPO) occurs with a rate constant of (1.1+/-0.1) x 10(4)M(-1)s(-1). The rate doubles at pH 5.0 and oxygen binding is reversible. At pH 7.0, the dissociation equilibrium constant of the oxyferrous form is (173+/-12)microM. The rate constant of dioxygen dissociation from compound III is much higher than conversion of compound III to ferric MPO (which is not affected by the oxygen concentration). This allows an efficient transition of compound III to redox intermediates which actually participate in the peroxidase or halogenation cycle of MPO.
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Affiliation(s)
- Walter Jantschko
- Metalloprotein Research Group, Division of Biochemistry, Department of Chemistry, BOKU-University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
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11
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Valderrama B, Ayala M, Vazquez-Duhalt R. Suicide inactivation of peroxidases and the challenge of engineering more robust enzymes. CHEMISTRY & BIOLOGY 2002; 9:555-65. [PMID: 12031662 DOI: 10.1016/s1074-5521(02)00149-7] [Citation(s) in RCA: 231] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
As the number of industrial applications for proteins continues to expand, the exploitation of protein engineering becomes critical. It is predicted that protein engineering can generate enzymes with new catalytic properties and create desirable, high-value, products at lower production costs. Peroxidases are ubiquitous enzymes that catalyze a variety of oxygen-transfer reactions and are thus potentially useful for industrial and biomedical applications. However, peroxidases are unstable and are readily inactivated by their substrate, hydrogen peroxide. Researchers rely on the powerful tools of molecular biology to improve the stability of these enzymes, either by protecting residues sensitive to oxidation or by devising more efficient intramolecular pathways for free-radical allocation. Here, we discuss the catalytic cycle of peroxidases and the mechanism of the suicide inactivation process to establish a broad knowledge base for future rational protein engineering.
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Affiliation(s)
- Brenda Valderrama
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, AP 510-3 Cuernavaca, Morelos 62250, México.
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12
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Couture M, Stuehr DJ, Rousseau DL. The ferrous dioxygen complex of the oxygenase domain of neuronal nitric-oxide synthase. J Biol Chem 2000; 275:3201-5. [PMID: 10652305 DOI: 10.1074/jbc.275.5.3201] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mechanisms by which nitric-oxide synthases (NOSs) bind and activate oxygen at their P450-type heme active site in order to synthesize nitric oxide from the substrate L-arginine are mostly unknown. To obtain information concerning the structure and properties of the first oxygenated intermediate of the enzymatic cycle, we have used a rapid continuous flow mixer and resonance Raman spectroscopy to generate and identify the ferrous dioxygen complex of the oxygenase domain of nNOS (Fe(2+)O(2) nNOSoxy). We detect a line at 1135 cm(-1) in the resonance Raman spectrum of the intermediate formed from 0.6 to 3.0 ms after the rapid mixing of the ferrous enzyme with oxygen that is shifted to 1068 cm(-1) with (18)O(2). This line is assigned as the O-O stretching mode (nu(O-O)) of the oxygenated complex of nNOSoxy. Rapid mixing experiments performed with nNOSoxy saturated with L-arginine or N(omega)-hydroxy-L-arginine, in the presence or absence of (6R)-5,6, 7,8-tetrahydro-L-biopterin, reveal that the nu(O-O) line is insensitive to the presence of the substrate and the pterin. The optical spectrum of this ferrous dioxygen species, with a Soret band wavelength maximum at 430 nm, confirms the identification of the previously reported oxygenated complexes generated by stopped flow techniques.
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Affiliation(s)
- M Couture
- Department of Physiology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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14
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Metodiewa D, Dunford HB. One-electron reduction of chloroperoxidase by radiolytically generated electrons. Biochem Biophys Res Commun 1990; 168:1311-7. [PMID: 2346488 DOI: 10.1016/0006-291x(90)91172-o] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Upon irradiation of aqueous ethylene glycol/water solutions of native chloroperoxidase (CPO) with 60Co-gamma rays at 77K one observes the one-electron reduction of the enzyme active site by radiolytically generated thermolyzed electrons. In the present study the first absorption spectrum of a low-spin ferrous form of CPO is reported which has peaks at 438, 532 and 563 nm, similar to those observed previously for cytochrome P-450. All previously described ferrous forms of CPO are high spin. In order to observe the final results of the CPO reaction with electrons, the spectral changes of native enzyme after room temperature-gamma-irradiation have also been investigated. Evidence of changes is also presented probably connected with disruption of the tertiary structure of enzyme, correlated with decrease of enzyme activity.
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Affiliation(s)
- D Metodiewa
- Institute of Applied Radiation Chemistry, Technical University of Lodz, Poland
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15
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Cai DY, Tien M. Characterization of the oxycomplex of lignin peroxidases from Phanerochaete chrysosporium: equilibrium and kinetics studies. Biochemistry 1990; 29:2085-91. [PMID: 2328240 DOI: 10.1021/bi00460a018] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The oxycomplexes (compound III, oxyperoxidase) of two lignin peroxidase isozymes, H1 (pI = 4.7) and H8 (pI = 3.5), were characterized in the present study. After generation of the ferroperoxidase by photochemical reduction with deazoflavin in the presence of EDTA, the oxycomplex is formed by mixing ferroperoxidase with O2. The oxycomplex of isozyme H8 is very stable, with an autoxidation rate at 25 degrees C too slow to measure at pH 3.5 or 7.0. In contrast, the oxycomplex of isozyme H1 has a half-life of 52 min at pH 4.5 and 29 min at pH 7.5 at 25 degrees C. The decay of isozyme H1 oxycomplex follows a single exponential. The half-lives of lignin peroxidase oxycomplexes are much longer than those observed with other peroxidases. The binding of O2 to ferroperoxidase to form the oxycomplex was studied by stopped-flow methods. At 20 degrees C, the second-order rate constants for O2 binding are 2.3 X 10(5) and 8.9 X 10(5) M-1 s-1 for isozyme H1 and 6.2 X 10(4) and 3.5 X 10(5) M-1 s-1 for isozyme H8 at pH 3.6 and pH 6.8, respectively. The dissociation rate constants for the oxycomplex of isozyme H1 (3.8 Z 10(-3) s-1) and isozyme H8 (1.0 X 10(-3) s-1) were measured at pH 3.6 by CO trapping. Thus, the equilibrium constants (K, calculated from kon/koff) for both isozymes H1 (7.0 X 10(7) M-1) and H8 (6.2 X 10(7) M-1) are higher than that of myoglobin (1.9 Z 10(6) M-1).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- D Y Cai
- Department of Molecular and Cell Biology, Pennsylvania State University, University Park 16802
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16
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EXAFS Spectroscopy of heme-containing oxygenases and peroxidases. METAL COMPLEXES WITH TETRAPYRROLE LIGANDS II 1990. [DOI: 10.1007/3-540-52899-7_1] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Metodiewa D, Pickard M, Dunford HB. The reactions of chloroperoxidase in the presence of xanthine/xanthine oxidase. Biochem Biophys Res Commun 1989; 159:1086-92. [PMID: 2930551 DOI: 10.1016/0006-291x(89)92220-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Spectral data are presented which indicate that chloroperoxidase is converted to compound II during the reaction with superoxide/hydrogen peroxide generated in the xanthine/xanthine oxidase system. Upon completion of compound II formation, compound II returns back to the native state of chloroperoxidase without formation of detectable intermediates. It is shown that chloroperoxidase acts as a superoxide scavenger but less effectively than superoxide dismutase. Addition of chloride ion enhances the rate of decay of compound II to native enzyme, showing that chloride ion is oxidized to a chlorine atom in the presence of compound II.
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Affiliation(s)
- D Metodiewa
- Department of Chemistry, University of Alberta, Edmonton, Canada
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18
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Ohlsson PI, Blanck J, Ruckpaul K. Reduction of lactoperoxidase by the dithionite anion monomer. EUROPEAN JOURNAL OF BIOCHEMISTRY 1986; 158:451-4. [PMID: 3732278 DOI: 10.1111/j.1432-1033.1986.tb09774.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The reduction of lactoperoxidase with sodium dithionite has been studied by means of stopped-flow spectrophotometry in an anaerobic system. Under pseudo-first-order conditions the rate constant was found to be linearly dependent on the square root of the dithionite concentration, which confirms the monomeric radical, SO2- as the reducing species. The second-order rate constant is moderately influenced by increased ionic strength but drastically increased at lower pH. The pH dependence supports the previously suggested existence of a carboxyl group, essential to the different enzymatic functions of lactoperoxidase. The second-order rate constant for the reduction of lactoperoxidase at pH 7.0 (kappa 1 = 1.3 X 10(5) M-1 s-1) was about three times higher than the rate constant for the reduction of cyanide-bound lactoperoxidase and two times the rate constant for the reduction of the fluoride-lactoperoxidase complex.
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19
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Cuperus RA, Muijsers AO, Wever R. The superoxide dismutase activity of myeloperoxidase; formation of compound III. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 871:78-84. [PMID: 3008848 DOI: 10.1016/0167-4838(86)90135-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The reaction of superoxide anions with myeloperoxidase (donor: hydrogen-peroxide oxidoreductase, EC 1.11.1.7), which results in the formation of Compound III of myeloperoxidase, was investigated. It is shown that myeloperoxidase has a high affinity for superoxide anions because formation of Compound III was only partially inhibited by high concentrations of superoxide dismutase. Furthermore, when superoxide anions were generated in a mixture of both cytochrome c and myeloperoxidase in the absence of Cl-, only Compound III was formed and reduction of cytochrome c was not observed. In the presence of Cl-, Compound III was also formed and reduction of cytochrome c was inhibited. From the results described in this paper we conclude that Compound III is able to react with superoxide anions, probably resulting in formation of an intermediate (Compound I) which is catalytically active in the oxidation of Cl- to yield hypochlorous acid (HOCl). Because Compound III of myeloperoxidase is formed in phagocytosing neutrophils (Winterbourn, C.C., Garcia, R.C. and Segal, A.W. (1985) Biochem. J. 228, 583-592) we propose that, in vivo, myeloperoxidase also acts as a superoxide dismutase, and via formation of Compound I uses superoxide anions in the formation of HOCl.
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Lambeir AM, Markey CM, Dunford HB, Marnett LJ. Spectral properties of the higher oxidation states of prostaglandin H synthase. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)95676-0] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Sono M, Eble KS, Dawson JH, Hager LP. Preparation and properties of ferrous chloroperoxidase complexes with dioxygen, nitric oxide, and an alkyl isocyanide. Spectroscopic dissimilarities between the oxygenated forms of chloroperoxidase and cytochrome P-450. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(17)36288-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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