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Suh LYK, Babu D, Tonoyan L, Reiz B, Whittal R, Tabatabaei-Dakhili SA, Morgan AG, Velázquez-Martínez CA, Siraki AG. Myeloperoxidase-mediated oxidation of edaravone produces an apparent non-toxic free radical metabolite and modulates hydrogen peroxide-mediated cytotoxicity in HL-60 cells. Free Radic Biol Med 2019; 143:422-432. [PMID: 31445206 DOI: 10.1016/j.freeradbiomed.2019.08.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 08/13/2019] [Accepted: 08/20/2019] [Indexed: 01/15/2023]
Abstract
Edaravone is considered to be a potent antioxidant drug known to scavenge free radical species and prevent free radical-induced lipid peroxidation. In this study, we investigated the effect of edaravone on the myeloperoxidase (MPO) activity, an enzyme responsible for the production of an array of neutrophil-derived oxidants that can cause cellular damage. The addition of edaravone to the reaction of MPO and hydrogen peroxide (H2O2) significantly enhanced the reduction of MPO Compound II back to native MPO. Interestingly, the MPO-mediated production of toxic hypochlorous acid exhibited a concentration-dependent biphasic effect, with the apparent optimal edaravone concentration at 10 μM. Oxidation of edaravone by MPO was examined by various analytical methods. An MPO-catalyzed product(s) of edaravone was identified at 350 nm by kinetic analysis of UV-Vis spectroscopy. Several MPO-catalyzed metabolites of edaravone were proposed from the LC-MS analyses, including oxidized dimers from edaravone radicals. Electron spin resonance (ESR) spin trapping detected a carbon-centred radical metabolite of edaravone. NMR studies revealed that there are two exchangeable hydrogens, one of which is on the α-carbon, justifying the carbon-centred edaravone radical produced from MPO. Despite the formation of an edaravone carbon-radical metabolite, it did not appear to effectively oxidize GSH (in comparison with phenoxyl radicals). Viability (ATP) and cytotoxicity (LDH release) assays showed a concentration-dependent effect of edaravone on HL-60 cells treated with either a bolus concentration of 30 μM H2O2 or a flux of H2O2 generated by 5 mM glucose and 10 mU/mL glucose oxidase. The H2O2-induced toxicity was ameliorated at high edaravone concentrations (100-200 μM). In contrast, low concentrations of edaravone (1-10 μM) exacerbated the H2O2-induced toxicity. However, the effect of edaravone at low concentration (0-10 μM) appeared more prominent with the LDH assay only. The cellular findings correlated with the biochemical studies with respect to hypochlorous acid formation. These findings provide interesting perspectives regarding the duality of edaravone as an antioxidant drug.
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Affiliation(s)
- Lindsey Y K Suh
- Faculty of Pharmacy & Pharmaceutical Sciences, Katz Group-Rexall Centre for Pharmacy and Health Research, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
| | - Dinesh Babu
- Faculty of Pharmacy & Pharmaceutical Sciences, Katz Group-Rexall Centre for Pharmacy and Health Research, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
| | - Lusine Tonoyan
- Faculty of Pharmacy & Pharmaceutical Sciences, Katz Group-Rexall Centre for Pharmacy and Health Research, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
| | - Béla Reiz
- Department of Chemistry, 11227 Saskatchewan Drive, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada
| | - Randy Whittal
- Department of Chemistry, 11227 Saskatchewan Drive, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada
| | - S Amirhossein Tabatabaei-Dakhili
- Faculty of Pharmacy & Pharmaceutical Sciences, Katz Group-Rexall Centre for Pharmacy and Health Research, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
| | - Andrew G Morgan
- Faculty of Pharmacy & Pharmaceutical Sciences, Katz Group-Rexall Centre for Pharmacy and Health Research, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
| | - Carlos A Velázquez-Martínez
- Faculty of Pharmacy & Pharmaceutical Sciences, Katz Group-Rexall Centre for Pharmacy and Health Research, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada.
| | - Arno G Siraki
- Faculty of Pharmacy & Pharmaceutical Sciences, Katz Group-Rexall Centre for Pharmacy and Health Research, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada.
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2
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Methionine in Proteins: It's Not Just for Protein Initiation Anymore. Neurochem Res 2018; 44:247-257. [PMID: 29327308 DOI: 10.1007/s11064-017-2460-0] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 12/19/2017] [Accepted: 12/26/2017] [Indexed: 12/21/2022]
Abstract
Methionine in proteins is often thought to be a generic hydrophobic residue, functionally replaceable with another hydrophobic residue such as valine or leucine. This is not the case, and the reason is that methionine contains sulfur that confers special properties on methionine. The sulfur can be oxidized, converting methionine to methionine sulfoxide, and ubiquitous methionine sulfoxide reductases can reduce the sulfoxide back to methionine. This redox cycle enables methionine residues to provide a catalytically efficient antioxidant defense by reacting with oxidizing species. The cycle also constitutes a reversible post-translational covalent modification analogous to phosphorylation. As with phosphorylation, enzymatically-mediated oxidation and reduction of specific methionine residues functions as a regulatory process in the cell. Methionine residues also form bonds with aromatic residues that contribute significantly to protein stability. Given these important functions, alteration of the methionine-methionine sulfoxide balance in proteins has been correlated with disease processes, including cardiovascular and neurodegenerative diseases. Methionine isn't just for protein initiation.
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Elvitigala DAS, Whang I, Nam BH, Park HC, Lee J. Identification of a myeloperoxidase-like ortholog from rock bream (Oplegnathus fasciatus), deciphering its transcriptional responses to induced pathogen stress. FISH & SHELLFISH IMMUNOLOGY 2015; 45:477-485. [PMID: 25982406 DOI: 10.1016/j.fsi.2015.05.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 05/01/2015] [Accepted: 05/05/2015] [Indexed: 06/04/2023]
Abstract
Myeloperoxidases (MPOs) are heme-linked oxidative stress-generating enzymes found abundantly in azurophilic granules of polymorphonuclear neutrophils. Mature MPOs act as potent antimicrobial agents by producing hypohalous acids using hydrogen peroxide and halide ions as substrates. These acids can readily oxidize reactive groups of biomolecules on invading microbes. In this study, we identified and characterized a homolog of MPO from rock bream (Oplegnathus fasciatus), designated as RbMPO. We analyzed the RbMPO gene for its basal expression level in physiologically important tissues and for transcriptional changes under different pathogenic stress conditions. The complete coding sequence of RbMPO consisted of 2652 nucleotides encoding an 884 amino acid sequence with a predicted molecular mass of 99.7 kDa. Our in silico analysis confirmed the typical MPO domain arrangement in RbMPO, including the propeptide, large chain and heavy chain, along with the heme peroxidase signature. Intriguingly, a C1q domain was also identified in the C-terminal region of the derived amino acid sequence. Most of the known functionally important residues of MPOs are found to be well conserved in RbMPO, showing a close evolutionary relationship with other teleostan MPOs, particularly with that of mandarin fish. RbMPO exhibited a ubiquitous basal expression in physiologically relevant tissues, with particularly high expression levels in blood cells. Basal transcript levels of RbMPO in gill and spleen tissues were found to change upon different pathogen or pathogen-derived mitogen stimulation, with detectable inductive responses. Together, these data suggest the potential involvement of RbMPO in the innate immune response in rock bream.
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Affiliation(s)
- Don Anushka Sandaruwan Elvitigala
- Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea; Fish Vaccine Development Center, Jeju National University, Jeju Special Self-Governing Province 690-756, Republic of Korea
| | - Ilson Whang
- Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea; Fish Vaccine Development Center, Jeju National University, Jeju Special Self-Governing Province 690-756, Republic of Korea
| | - Bo-Hye Nam
- Biotechnology Research Division, National Fisheries Research and Development Institute, 408-1 Sirang-ri, Gijang-up, Gijang-gun, Busan 619-705, Republic of Korea
| | - Hae-Chul Park
- Graduate School of Medicine, Korea University, Ansan, Gyeonggido 425-707, Republic of Korea
| | - Jehee Lee
- Department of Marine Life Sciences, School of Marine Biomedical Sciences, Jeju National University, Jeju Self-Governing Province 690-756, Republic of Korea; Fish Vaccine Development Center, Jeju National University, Jeju Special Self-Governing Province 690-756, Republic of Korea.
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4
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Inactivation of myeloperoxidase by benzoic acid hydrazide. Arch Biochem Biophys 2015; 570:14-22. [PMID: 25688920 DOI: 10.1016/j.abb.2015.01.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 01/20/2015] [Accepted: 01/24/2015] [Indexed: 12/12/2022]
Abstract
Myeloperoxidase (MPO) is expressed by myeloid cells for the purpose of catalyzing the formation of hypochlorous acid, from chloride ions and reaction with a hydrogen peroxide-charged heme covalently bound to the enzyme. Most peroxidase enzymes both plant and mammalian are inhibited by benzoic acid hydrazide (BAH)-containing compounds, but the mechanism underlying MPO inhibition by BAH compounds is largely unknown. Recently, we reported MPO inhibition by BAH and 4-(trifluoromethyl)-BAH was due to hydrolysis of the ester bond between MPO heavy chain glutamate 242 ((HC)Glu(242)) residue and the heme pyrrole A ring, freeing the heme linked light chain MPO subunit from the larger remaining heavy chain portion. Here we probed the structure and function relationship behind this ester bond cleavage using a panel of BAH analogs to gain insight into the constraints imposed by the MPO active site and channel leading to the buried protoporphyrin IX ring. In addition, we show evidence that destruction of the heme ring does not occur by tracking the heme prosthetic group and provide evidence that the mechanism of hydrolysis follows a potential attack of the (HC)Glu(242) carbonyl leading to a rearrangement causing the release of the vinyl-sulfonium linkage between (HC)Met(243) and the pyrrole A ring.
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Huang J, Smith F, Panizzi P. Ordered cleavage of myeloperoxidase ester bonds releases active site heme leading to inactivation of myeloperoxidase by benzoic acid hydrazide analogs. Arch Biochem Biophys 2014; 548:74-85. [PMID: 24632143 DOI: 10.1016/j.abb.2014.02.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 02/17/2014] [Accepted: 02/27/2014] [Indexed: 02/02/2023]
Abstract
Myeloperoxidase (MPO) catalyzes the breakdown of hydrogen peroxide and the formation of the potent oxidant hypochlorous acid. We present the application of the fluorogenic peroxidase substrate 10-acetyl-3,7-dihydroxyphenoxazine (ADHP) in steady-state and transient kinetic studies of MPO function. Using initial kinetic parameters for the MPO system, we characterized under the same conditions a number of gold standards for MPO inhibition, namely 4-amino benzoic acid hydrazide (4-ABAH), isoniazid and NaN3 before expanding our focus to isomers of 4-ABAH and benzoic acid hydrazide analogs. We determined that in the presence of hydrogen peroxide that 4-ABAH and its isomer 2-ABAH are both slow-tight binding inhibitors of MPO requiring at least two steps, whereas NaN3 and isoniazid-based inhibition has a single observable step. We also determined that MPO inhibition by benzoic acid hydrazide and 4-(trifluoromethyl) benzoic acid hydrazide was due to hydrolysis of the ester bond between MPO heavy chain Glu 242 residue and the heme pyrrole A ring, freeing the light chain and heme b fragment from the larger remaining MPO heavy chain. This new mechanism would essentially indicate that the benzoic acid hydrazide analogs impart inhibition through initial ejection of the heme catalytic moiety without prior loss of the active site iron.
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Affiliation(s)
- Jiansheng Huang
- Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, United States
| | - Forrest Smith
- Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, United States
| | - Peter Panizzi
- Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, United States.
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Abstract
Neutrophils (PMN) represent the dominant cell in the acute response to microbial infection and can contribute to some of the tissue damage that accompanies sterile inflammation. Effective antimicrobial activity in neutrophil phagosomes reflects the combined action of soluble agents in plasma with PMN-derived reactive oxygen species and granule proteins, including the azurophilic granule protein myeloperoxidase (MPO). The inhibition or the absence of the MPO-H2O2-halide system results in marked reduction in PMN killing of a variety of microbes, implicating its relative prominence in the hierarchy of PMN antimicrobial systems. Although the most profound clinical defects are manifested in patients lacking the capacity to generate reactive oxygen species, as seen in chronic granulomatous disease, an inherited deficiency of MPO can also increase the frequency or the severity of clinical infections.Like related peroxidases expressed in animals, MPO can catalyze both one- and two-electron oxidations, thereby mediating peroxidation and halogenation, respectively. The presence of each activity can be assessed in inflammatory fluids or by stimulated PMN. Furthermore, histochemical staining provides an assessment of functional MPO in tissue or within PMN, and immunoblotting of isolated PMN for MPO can provide additional insight into the molecular basis of the observed absence of functional enzyme.
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7
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Paumann-Page M, Furtmüller PG, Hofbauer S, Paton LN, Obinger C, Kettle AJ. Inactivation of human myeloperoxidase by hydrogen peroxide. Arch Biochem Biophys 2013; 539:51-62. [PMID: 24035742 PMCID: PMC3808540 DOI: 10.1016/j.abb.2013.09.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 09/02/2013] [Accepted: 09/04/2013] [Indexed: 12/29/2022]
Abstract
Human myeloperoxidase (MPO) uses hydrogen peroxide generated by the oxidative burst of neutrophils to produce an array of antimicrobial oxidants. During this process MPO is irreversibly inactivated. This study focused on the unknown role of hydrogen peroxide in this process. When treated with low concentrations of H2O2 in the absence of reducing substrates, there was a rapid loss of up to 35% of its peroxidase activity. Inactivation is proposed to occur via oxidation reactions of Compound I with the prosthetic group or amino acid residues. At higher concentrations hydrogen peroxide acts as a suicide substrate with a rate constant of inactivation of 3.9 × 10(-3) s(-1). Treatment of MPO with high H2O2 concentrations resulted in complete inactivation, Compound III formation, destruction of the heme groups, release of their iron, and detachment of the small polypeptide chain of MPO. Ten of the protein's methionine residues were oxidized and the thermal stability of the protein decreased. Inactivation by high concentrations of H2O2 is proposed to occur via the generation of reactive oxidants when H2O2 reacts with Compound III. These mechanisms of inactivation may occur inside neutrophil phagosomes when reducing substrates for MPO become limiting and could be exploited when designing pharmacological inhibitors.
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Affiliation(s)
- Martina Paumann-Page
- Centre for Free Radical Research, University of Otago Christchurch, Christchurch, New Zealand
- Department of Chemistry, Division of Biochemistry, BOKU – University of Natural Resources and Life Sciences, Muthgasse 18, Vienna, Austria
| | - Paul G. Furtmüller
- Department of Chemistry, Division of Biochemistry, BOKU – University of Natural Resources and Life Sciences, Muthgasse 18, Vienna, Austria
| | - Stefan Hofbauer
- Department of Chemistry, Division of Biochemistry, BOKU – University of Natural Resources and Life Sciences, Muthgasse 18, Vienna, Austria
| | - Louise N. Paton
- Centre for Free Radical Research, University of Otago Christchurch, Christchurch, New Zealand
| | - Christian Obinger
- Department of Chemistry, Division of Biochemistry, BOKU – University of Natural Resources and Life Sciences, Muthgasse 18, Vienna, Austria
| | - Anthony J. Kettle
- Centre for Free Radical Research, University of Otago Christchurch, Christchurch, New Zealand
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8
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Retinoid agonist Am80-enhanced neutrophil bactericidal activity arising from granulopoiesis in vitro and in a neutropenic mouse model. Blood 2012; 121:996-1007. [PMID: 23243275 DOI: 10.1182/blood-2012-06-436022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Despite advances in the therapeutic use of recombinant granulocyte colony-stimulating factor (G-CSF) to promote granulopoiesis of human hematopoietic stem cells (HSCs), neutropenia remains one of the most serious complications of cancer chemotherapy. We discovered that retinoid agonist Am80 (tamibarotene) is more potent than G-CSF in coordinating neutrophil differentiation and immunity development. Am80-induced neutrophils (AINs) either in vitro or in neutropenic mouse model displayed strong bactericidal activities, similar to those of human peripheral blood neutrophils (PBNs) or mouse peripheral blood neutrophils (MPBNs) but markedly greater than did G-CSF–induced neutrophils (GINs). In contrast to GINs but similar to PBNs, the enhanced bacterial killing by AINs accompanied both better granule maturation and greater coexpression of CD66 antigen with the integrin β2 subunit CD18. Consistently, anti-CD18 antibody neutralized Am80-induced bactericidal activities of AINs. These studies demonstrate that Am80 is more effective than G-CSF in promoting neutrophil differentiation and bactericidal activities, probably through coordinating the functional interaction of CD66 with CD18 to enhance the development of neutrophil immunity during granulopoiesis. Our findings herein suggest a molecular rationale for developing new therapy against neutropenia using Am80 as a cost-effective treatment option.
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9
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Nathani R, Moody P, Smith MEB, Fitzmaurice RJ, Caddick S. Bioconjugation of green fluorescent protein via an unexpectedly stable cyclic sulfonium intermediate. Chembiochem 2012; 13:1283-5. [PMID: 22639110 PMCID: PMC3487180 DOI: 10.1002/cbic.201200231] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Indexed: 11/12/2022]
Abstract
Smooth converter: Bioconjugation of superfolder GFP involving the formation of an unusually stable, and unprecedented, cyclic sulfonium species is described. This sulfonium can undergo smooth reaction with a range of nucleophiles to give sulfur-, selenium- and azide-modified GFP derivatives in high conversions.
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Affiliation(s)
- Ramiz Nathani
- Department of Chemistry, University College LondonLondon, WC1H 0AJ (UK)
| | - Paul Moody
- Department of Chemistry, University College LondonLondon, WC1H 0AJ (UK)
| | - Mark E B Smith
- Department of Chemistry, University College LondonLondon, WC1H 0AJ (UK)
| | | | - Stephen Caddick
- Department of Chemistry, University College LondonLondon, WC1H 0AJ (UK)
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Geoghegan KF, Varghese AH, Feng X, Bessire AJ, Conboy JJ, Ruggeri RB, Ahn K, Spath SN, Filippov SV, Conrad SJ, Carpino PA, Guimarães CRW, Vajdos FF. Deconstruction of Activity-Dependent Covalent Modification of Heme in Human Neutrophil Myeloperoxidase by Multistage Mass Spectrometry (MS4). Biochemistry 2012; 51:2065-77. [DOI: 10.1021/bi201872j] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
| | | | - Xidong Feng
- Pfizer Worldwide Research, Groton, Connecticut
06340, United States
| | | | - James J. Conboy
- Pfizer Worldwide Research, Groton, Connecticut
06340, United States
| | - Roger B. Ruggeri
- Pfizer Worldwide Research, Groton, Connecticut
06340, United States
| | - Kay Ahn
- Pfizer Worldwide Research, Groton, Connecticut
06340, United States
| | | | | | - Steven J. Conrad
- Pfizer Worldwide Research, Groton, Connecticut
06340, United States
| | | | | | - Felix F. Vajdos
- Pfizer Worldwide Research, Groton, Connecticut
06340, United States
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Amanzada A, Malik IA, Nischwitz M, Sultan S, Naz N, Ramadori G. Myeloperoxidase and elastase are only expressed by neutrophils in normal and in inflamed liver. Histochem Cell Biol 2011; 135:305-15. [PMID: 21327394 PMCID: PMC3052504 DOI: 10.1007/s00418-011-0787-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/28/2011] [Indexed: 12/13/2022]
Abstract
Myeloperoxidase (MPO) is involved in acute and chronic inflammatory diseases. The source of MPO in acute liver diseases is still a matter of debate. Therefore, we analysed MPO-gene expression on sections from normal and acutely damaged [carbon tetrachloride-(CCl4) or whole liver γ-Irradiation] rat liver by immunohistochemistry, real time PCR and Western blot analysis of total RNA and protein. Also total RNA and protein from isolated Kupffer cells, hepatic stellate cells, Hepatocytes, endothelial cells and neutrophil granulocytes (NG) was analysed by real time PCR and Western blot, respectively. Sections of acutely injured human liver were prepared for MPO and CD68 immunofluorescence double staining. In normal rat liver MPO was detected immunohistochemically and by immunofluorescence double staining only in single NG. No MPO was detected in isolated parenchymal and non-parenchymal cell populations of the normal rat liver. In acutely damaged rat liver mRNA of MPO increased 2.8-fold at 24 h after administration of CCl4 and 3.3-fold at 3 h after γ-Irradiation and MPO was detected by immunofluorescence double staining only in elastase (NE) positive NGs but not in macrophages (ED1 or CD68 positive cells). Our results demonstrate that, increased expression of MPO in damaged rat and human liver is due to recruited elastase positive NGs.
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Affiliation(s)
- Ahmad Amanzada
- Department of Gastroenterology and Endocrinology, University Clinic of the Georg-August-University, Robert-Koch-Straße 40, 37075, Göttingen, Germany.
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12
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Pressler BM, Robarge ME, Anderson KI. Partial characterization of feline myeloperoxidase and investigation of its potential role as an autoantigen in hyperthyroid cats. Am J Vet Res 2009; 70:869-78. [PMID: 19566472 DOI: 10.2460/ajvr.70.7.869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To partially characterize the cDNA, amino acid sequence, and tertiary structure of feline myeloperoxidase, describe its cellular location in mature granulocytes, and determine whether hyperthyroid cats have anti-myeloperoxidase antibody. SAMPLE POPULATION Bone marrow RNA and whole blood from cats of various sources and feline serum samples submitted for measurement of total thyroxine concentration from September 2006 to July 2007. PROCEDURES Feline myeloperoxidase cDNA was amplified from bone marrow RNA; presumptive splice sites were determined by comparison with human sequences. Intracellular localization of myeloperoxidase in granulocytes was determined by use of immunofluorescence and electron microscopy, and molecular weight and partial tertiary structure were determined by use of immunoblotting of granulocyte lysates. Anti-human myeloperoxidase (hMPO) antibody was detected via ELISA. RESULTS A 2,493-bp sequence encompassing the 2,160-bp cDNA with presumably the same number and size of exons as hMPO was generated. Translation predicted 85% homology with hMPO. Feline myeloperoxidase was localized to neutrophil primary granules, and immunoblotting revealed heavy and light bands with molecular weights similar to those of hMPO. The prevalence of anti-hMPO antibody did not differ between nonhyperthyroid and hyperthyroid cats or among hyperthyroid cats subclassified by treatment modality. CONCLUSIONS AND CLINICAL RELEVANCE Moderate homology existed between feline myeloperoxidase and hMPO cDNA and protein. Although findings suggested a similar tertiary structure and function for the 2 proteins, they also suggested that inability to detect a high prevalence of anti-hMPO antibody in hyperthyroid cats may be attributable to antigenic differences between the human and feline proteins rather than a lack of autoantibody.
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Affiliation(s)
- Barrak M Pressler
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA
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13
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Sheikh IA, Singh AK, Singh N, Sinha M, Singh SB, Bhushan A, Kaur P, Srinivasan A, Sharma S, Singh TP. Structural evidence of substrate specificity in mammalian peroxidases: structure of the thiocyanate complex with lactoperoxidase and its interactions at 2.4 A resolution. J Biol Chem 2009; 284:14849-56. [PMID: 19339248 PMCID: PMC2685666 DOI: 10.1074/jbc.m807644200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 03/18/2009] [Indexed: 11/06/2022] Open
Abstract
The crystal structure of the complex of lactoperoxidase (LPO) with its physiological substrate thiocyanate (SCN(-)) has been determined at 2.4A resolution. It revealed that the SCN(-) ion is bound to LPO in the distal heme cavity. The observed orientation of the SCN(-) ion shows that the sulfur atom is closer to the heme iron than the nitrogen atom. The nitrogen atom of SCN(-) forms a hydrogen bond with a water (Wat) molecule at position 6'. This water molecule is stabilized by two hydrogen bonds with Gln(423) N(epsilon2) and Phe(422) oxygen. In contrast, the placement of the SCN(-) ion in the structure of myeloperoxidase (MPO) occurs with an opposite orientation, in which the nitrogen atom is closer to the heme iron than the sulfur atom. The site corresponding to the positions of Gln(423), Phe(422) oxygen, and Wat(6)' in LPO is occupied primarily by the side chain of Phe(407) in MPO due to an entirely different conformation of the loop corresponding to the segment Arg(418)-Phe(431) of LPO. This arrangement in MPO does not favor a similar orientation of the SCN(-) ion. The orientation of the catalytic product OSCN(-) as reported in the structure of LPO.OSCN(-) is similar to the orientation of SCN(-) in the structure of LPO.SCN(-). Similarly, in the structure of LPO.SCN(-).CN(-), in which CN(-) binds at Wat(1), the position and orientation of the SCN(-) ion are also identical to that observed in the structure of LPO.SCN.
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Affiliation(s)
- Ishfaq Ahmed Sheikh
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110 029, India
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14
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Ex Vivo-Expanded Bone Marrow CD34+Derived Neutrophils Have Limited Bactericidal Ability. Stem Cells 2008; 26:2552-63. [DOI: 10.1634/stemcells.2008-0328] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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15
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Abstract
Polymorphonuclear neutrophils (PMN) represent the dominant cell in the acute response to microbial infection. Effective antimicrobial activity reflects the combined action of soluble agents in plasma with PMN-derived reactive oxygen species and granule proteins, including the azurophilic granule protein myeloperoxidase (MPO). The inhibition or absence of the MPO-H2O2-halide system results in marked reduction in PMN killing of a variety of microbes, implicating its relative prominence in the hierarchy of PMN antimicrobial systems. Although the most profound clinical defects are manifested in patients lacking the capacity to generate reactive oxygen species, as seen in chronic granulomatous disease, an inherited deficiency of MPO can also increase the frequency or severity of clinical infections. As a first step in evaluating the MPO-dependent system, determination of peroxidase activity of isolated leukocytes enriched for PMN coupled with histochemical staining of leukocytes allows assessment of functional MPO within PMN. Immunoblotting of the isolated leukocytes for MPO provides additional information, supplying insight into the molecular basis of the observed absence of functional enzyme.
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Affiliation(s)
- William M Nauseef
- Department of Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa and Veterans Affairs Medical Center, Coralville, Iowa City, IA, USA
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16
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Reid GE, Roberts KD, Simpson RJ, O'Hair RAJ. Selective identification and quantitative analysis of methionine containing peptides by charge derivatization and tandem mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2005; 16:1131-50. [PMID: 15923125 DOI: 10.1016/j.jasms.2005.03.015] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2004] [Revised: 03/14/2005] [Accepted: 03/16/2005] [Indexed: 05/02/2023]
Abstract
To enable the development of a tandem mass spectrometry (MS/MS) based methodology for selective protein identification and differential quantitative analysis, a novel derivatization strategy is proposed, based on the formation of a "fixed-charge" sulfonium ion on the side-chain of a methionine amino acid residue contained within a protein or peptide of interest. The gas-phase fragmentation behavior of these side chain fixed charge sulfonium ion containing peptides is observed to result in exclusive loss of the derivatized side chain and the formation of a single characteristic product ion, independently of charge state or amino acid composition. Thus, fixed charge containing peptide ions may be selectively identified from complex mixtures, for example, by selective neutral loss scan mode MS/MS methods. Further structural interrogation of identified peptide ions may be achieved by subjecting the characteristic MS/MS product ion to multistage MS/MS (MS3) in a quadrupole ion trap mass spectrometer, or by energy resolved "pseudo" MS3 in a triple quadrupole mass spectrometer. The general principles underlying this fixed charge derivatization approach are demonstrated here by MS/MS, MS3 and "pseudo" MS3 analysis of side chain fixed-charge sulfonium ion derivatives of peptides containing methionine formed by reaction with phenacylbromide. Incorporation of "light" and "heavy" isotopically encoded labels into the fixed-charge derivatives facilitates the application of this method to the quantitative analysis of differential protein expression, via measurement of the relative abundances of the neutral loss product ions generated by dissociation of the light and heavy labeled peptide ions. This approach, termed "selective extraction of labeled entities by charge derivatization and tandem mass spectrometry" (SELECT), thereby offers the potential for significantly improved sensitivity and selectivity for the identification and quantitative analysis of peptides or proteins containing selected structural features, without requirement for extensive fractionation or otherwise enrichment from a complex mixture prior to analysis.
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Affiliation(s)
- Gavin E Reid
- Joint Proteomics Laboratory, The Ludwig Institute for Cancer Research and The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.
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17
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Lemansky P, Gerecitano-Schmidek M, Das RC, Schmidt B, Hasilik A. Targeting myeloperoxidase to azurophilic granules in HL-60 cells. J Leukoc Biol 2003; 74:542-50. [PMID: 12960244 DOI: 10.1189/jlb.1202616] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Myeloperoxidase (MPO) is a cationic protein and one of the major constituents of azurophilic granules in neutrophils. Here, we examined whether intracellular transport of MPO and serglycin, a chondroitin sulfate (CS)-bearing proteoglycan, is correlated. First, we examined binding of MPO to CS-Sepharose and measured an ionic interaction, which was disrupted by 200-400 mM NaCl. Next, HL-60 promyelocytes were activated with a phorbol ester, which induced an almost complete rerouting of serglycin from the granular to the secretory pathway, concomitant with a similar effect on MPO transport and secretion. We then used the membrane-permeable cross-linker dithiobis(succininmidylpropionate; DSP) after labeling HL-60 cells with [35S]methionine and [35S]cysteine for 19 h. Immunoprecipitation of MPO revealed its cross-linking to high molecular material having the appearance of a proteoglycan in sodium dodecyl sulfate-polyacrylamide gels. This assumption was confirmed by labeling HL-60 cells with [35S]sulfate for 10 min followed by DSP cross-linking and immunoprecipitation. From three granular enzymes immunoprecipitated, only the cationic MPO was cross-linked to [35S]sulfate-labeled serglycin in appreciable quantities, whereas cathepsin D or beta-N-acetylhexosaminidase was not. Thus, intracellular transport of MPO appears to be linked to that of serglycin. Extracts from high buoyant density organelles from human placenta containing MPO activity were subjected to CS-affinity chromatography. Proteins binding to CS were identified by mass spectrometry as MPO, lactoferrin, cathepsin G, and azurocidin/cationic antimicrobial protein of molecular weight 37 kDa, suggesting that serglycin may be a general transport vehicle for the cationic granular proteins of neutrophils.
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Affiliation(s)
- Peter Lemansky
- Institut für Physiologische Chemie, Philipps-Universität Marburg, Germany.
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18
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Yang Y, Anderson EJ. Antimicrobial activity of a porcine myeloperoxidase against plant pathogenic bacteria and fungi. J Appl Microbiol 2001. [DOI: 10.1046/j.1365-2672.1999.00652.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Y. Yang
- Department of Plant Pathology, University of Arkansas, Fayetteville, USA
| | - E. J. Anderson
- Department of Plant Pathology, University of Arkansas, Fayetteville, USA
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19
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Brown KE, Brunt EM, Heinecke JW. Immunohistochemical detection of myeloperoxidase and its oxidation products in Kupffer cells of human liver. THE AMERICAN JOURNAL OF PATHOLOGY 2001; 159:2081-8. [PMID: 11733358 PMCID: PMC1850615 DOI: 10.1016/s0002-9440(10)63059-3] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Oxidative damage to tissue proteins has been implicated in the pathogenesis of liver disease, but the mechanisms that promote oxidation in vivo are unclear. Hydrogen peroxide is transformed into an array of potentially damaging reactants by the heme protein myeloperoxidase. This proinflammatory enzyme is expressed by circulating neutrophils and monocytes but is generally thought to be absent from tissue macrophages. To determine whether myeloperoxidase is present in Kupffer cells, the fixed-tissue macrophages of liver, Western blot analysis, and immunohistochemistry were performed. Two different antibodies monospecific for myeloperoxidase identified a 60-kd protein, the predicted molecular mass of myeloperoxidase, in human liver extracts. Immunostaining detected the enzyme in sinusoidal lining cells of normal and diseased human livers. Immunofluorescence confocal microscopy demonstrated co-localization of myeloperoxidase and CD68, a monocyte/macrophage marker, in sinusoidal lining cells. Numerous myeloperoxidase-expressing cells were also evident in the fibrous septa of cirrhotic livers. Immunostaining with an antibody to proteins modified by hypochlorous acid, a characteristic product of the enzyme, indicated that myeloperoxidase is enzymatically active in cases of acute liver injury and cirrhosis. These findings identify myeloperoxidase as a component of human Kupffer cells. Oxidative damage resulting from the action of myeloperoxidase may contribute to acute liver injury and hepatic fibrogenesis.
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Affiliation(s)
- K E Brown
- John Cochran Veteran's Administration Medical Center, St. Louis, Missouri, USA.
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20
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Thomsen AR, Sottrup-Jensen L, Gleich GJ, Oxvig C. The status of half-cystine residues and locations of N-glycosylated asparagine residues in human eosinophil peroxidase. Arch Biochem Biophys 2000; 379:147-52. [PMID: 10864452 DOI: 10.1006/abbi.2000.1866] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The determination by protein chemistry methods of the half-cystine status in human eosinophil peroxidase (EPO) is reported. EPO is two-chained and has a total of 14 half-cystine residues. Cys141 and Cys152 form an intrachain bridge in the light chain of EPO. Disulfide bridges connect Cys253 and Cys263, Cys257 and Cys287, Cys359 and Cys370, Cys570 and Cys635, and Cys676 and Cys701, forming five intrachain disulfide bridges in the heavy chain of EPO. Cys291 and Cys455 are found to be unpaired, containing free sulfhydryl groups. The pattern of disulfide bridges is in agreement with that predicted from the X-ray crystallographic structure of canine myeloperoxidase (MPO) (Zeng, J., and Fenna, R. E. (1992) J. Mol. Biol. 226, 185-207) to be general for the class of mammalian peroxidases, including EPO, MPO, lactoperoxidase (LPO), and thyroid peroxidase (TPO). Of four candidate sites in EPO for attachment of glucosamine-based carbohydrate, Asn327 and Asn363 are occupied, whereas Asn700 and Asn708 are unsubstituted. Furthermore, a discrepancy in the literature regarding the sequence of residues 645-659 is resolved.
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Affiliation(s)
- A R Thomsen
- Department of Molecular and Structural Biology, University of Aarhus, Science Park, Gustav Wieds Vej 10 C, Arhus C, DK-8000, Denmark
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21
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Kooter IM, Moguilevsky N, Bollen A, van der Veen LA, Otto C, Dekker HL, Wever R. The sulfonium ion linkage in myeloperoxidase. Direct spectroscopic detection by isotopic labeling and effect of mutation. J Biol Chem 1999; 274:26794-802. [PMID: 10480885 DOI: 10.1074/jbc.274.38.26794] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The heme group of myeloperoxidase is covalently linked via two ester bonds to the protein and a unique sulfonium ion linkage involving Met(243). Mutation of Met(243) into Thr, Gln, and Val, which are the corresponding residues of eosinophil peroxidase, lactoperoxidase, and thyroid peroxidase, respectively, and into Cys was performed. The Soret band in the optical absorbance spectrum in the oxidized mutants is now found at approximately 411 nm. Both the pyridine hemochrome spectra and resonance Raman spectra of the mutants are affected by the mutation. In the Met(243) mutants the affinity for chloride has decreased 100-fold. All mutants have lost their chlorination activity, except for the M243T mutant, which still has 15% activity left. By Fourier transform infared difference spectroscopy it was possible to specifically detect the (13)CD(3)-labeled methionyl sulfonium ion linkage. We conclude that the sulfonium ion linkage serves two roles. First, it serves as an electron-withdrawing substituent via its positive charge, and, second, together with its neighboring residue Glu(242), it appears to be responsible for the lower symmetry of the heme group and distortion from the planar conformation normally seen in heme-containing proteins.
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Affiliation(s)
- I M Kooter
- E.C. Slater Institute, BioCentrum, University of Amsterdam, NL-1018 TV Amsterdam, The Netherlands
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22
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Nomura K, Hoshino K, Suzuki N. The primary and higher order structures of sea urchin ovoperoxidase as determined by cDNA cloning and predicted by homology modeling. Arch Biochem Biophys 1999; 367:173-84. [PMID: 10395733 DOI: 10.1006/abbi.1999.1219] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
At fertilization, sea urchin ovoperoxidase (OPO) is incorporated into a nascent fertilization envelope in association with proteoliaisin and plays an essential role in its hardening. By cDNA cloning based on the previously reported partial amino acid sequences of Hemicentrotus pulcherrimus OPO, the cDNA and deduced amino acid sequences of the enzyme precursor were determined. Its 814-residue sequence consists of 125-residue signal- plus pro-peptides and 689-residue mature enzyme and has 92.2 and 81.4% identity with the OPOs of Strongylocentrotus purpuratus and Lytechinus variegatus, respectively. Compared with human myeloperoxidase, it has 30.3% identity and 9.6% similarity and has an additional C-terminal sequence of about 100 residues, suggesting its possible role as the site for interaction with proteoliaisin, if not for the entire sequence. The linker peptide sequence between L- and H-chains (e.g., ASFVTG and FSFFTG) cleaved off upon activation in mammalian promyeloperoxidases is intrinsically lacking in OPO, uniquely rendering the single 70K polypeptide a basic unit. The positions of distal and proximal histidines, distal arginine, and six disulfide bridges are highly conserved among mammalian and sea urchin peroxidases. The secondary structure was predicted by EMBL-PHD on the Internet for the whole sequence of mature OPO, and both secondary and tertiary structures were predicted by Swiss-Model for the partial sequences residues 18-65 and 123-570 with canine myeloperoxidase as a template. The overall architecture of the OPO molecule is close to that of human myeloperoxidase but its secondary structure has some differences based on the sequence variation, as depicted by RasMol. Another software, Swiss-PdbViewer, produced a slightly but significantly different image of the OPO structure for the same predicted atomic coordinates. A discrepancy was also found between the secondary structures of human myeloperoxidase in the PDB file and in its Swiss-PdbViewer presentation.
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Affiliation(s)
- K Nomura
- Department of Biochemistry, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo, 173-0015, Japan.
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23
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Rae TD, Goff HM. The heme prosthetic group of lactoperoxidase. Structural characteristics of heme l and heme l-peptides. J Biol Chem 1998; 273:27968-77. [PMID: 9774411 DOI: 10.1074/jbc.273.43.27968] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The heme prosthetic group from the bovine milk enzyme lactoperoxidase (LPO), termed heme l, is isolated through an approach that combines proteolytic hydrolysis and reverse-phase high performance liquid chromatographic separation of the resulting digest. Application of different proteases yields either a peptide-bound heme (with trypsin and chymotrypsin) or a peptide-free heme (with proteinase K). Both heme l and heme l-peptide species were investigated by paramagnetic 1H NMR spectroscopy, electrospray mass spectrometry, and peptide sequence analysis. Paramagnetic 1H NMR experiments on the low spin bis(cyano)-Fe(III)heme l complex conclusively define the heme l structure as a 1,5-bis(hydroxymethyl) derivative of heme b. The electrospray mass spectrum of heme l confirms the two-site hydroxyl functionalization on this heme. Paramagnetic 1H NMR spectra of the high spin bis(dimethyl sulfoxide)-Fe(III) complexes of the isolated heme species provide information regarding peptide content. Sequence analyses of peptides released from two heme l-peptide species by base hydrolysis suggest that heme-protein ester linkages in lactoperoxidase occur between the two hydroxyl groups of heme l and the carboxylic side chains of glutamate 275 and aspartate 125. These results confirm the earlier reported structural proposal (Rae, T. D., and Goff, H. M. (1996) J. Am. Chem. Soc. 118, 2103-2104).
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Affiliation(s)
- T D Rae
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, USA
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24
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Andersson E, Hellman L, Gullberg U, Olsson I. The role of the propeptide for processing and sorting of human myeloperoxidase. J Biol Chem 1998; 273:4747-53. [PMID: 9468538 DOI: 10.1074/jbc.273.8.4747] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Myeloperoxidase (MPO), stored in azurophil granules of neutrophils, is critical for an optimal oxygen-dependent microbicidal activity of these cells. Pro-MPO goes through a stepwise proteolytic trimming with elimination of an amino-terminal propeptide to yield one heavy and one light polypeptide chain. The propeptide of MPO may have a role in retention and folding of the nascent protein into its tertiary structure or in targeting of pro-MPO for processing and storage in granules. A propeptide-deleted pro-MPO mutant (MPODeltapro) was constructed to determine if deletion of the propeptide interferes with processing and targeting after transfection to the myeloid 32D cell line. Transfection of full-length cDNA for human MPO results in normal processing and targeting of MPO to cytoplasmic dense organelles. Although the efficiency of incorporation was lower for MPODeltapro, both pro-MPO and MPODeltapro showed heme incorporation indicating that the propeptide is not critical for this process. Deletion of the propeptide results in synthesis of a protein that lacks processing into mature two-chain forms but rather is degraded intracellularly or secreted. The finding of continued degradation of MPODeltapro in the presence of lysosomotrophic agents or brefeldin A rules out that the observed degradation takes place after transfer to granules. Intracellular pro-MPO has high mannose oligosaccharide side chains, whereas stored mature MPO was found to have both high mannose and complex oligosaccharide side chains as judged by only partial sensitivity to endoglycosidase H. The propeptide may normally interfere with the generation of certain complex oligosaccharide chain(s) supported by the finding of high mannose side chains in secreted pro-MPO and lack of them in MPODeltapro that contained complex oligosaccharide side chains only. In conclusion, elimination of the propeptide of pro-MPO blocks the maturation process and abolishes accumulation of the final product in granules suggesting a critical role of the propeptide for late processing of pro-MPO and targeting for storage in granules.
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Affiliation(s)
- E Andersson
- Department of Hematology, Research Department 2, E-blocket, University Hospital, S-221 85 Lund, Sweden
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25
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Myeloperoxidase Fragments Reacting with Serum from a Patient with Myeloperoxidase-Anti-Neutrophil Cytoplasmic Antibody-Positive Glomerulonephritis. J Infect Chemother 1997. [DOI: 10.1007/bf02491508] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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26
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Austin GE, Chan WC, Zhao W, Racine M. Myeloperoxidase gene expression in normal granulopoiesis and acute leukemias. Leuk Lymphoma 1994; 15:209-26. [PMID: 7866270 DOI: 10.3109/10428199409049717] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Myeloperoxidase (MPO) is an abundant heme protein found in granulocytes and monocytes, which plays an important role in host defense against infection. MPO enzyme activity as determined by light microscopic cytochemistry has long been an important marker used in the diagnosis of acute leukemias and other hematopoietic disorders. Recently, MPO expression has been studied at the electron microscopic level, and monoclonal antibodies (mAbs) against MPO protein have been developed. Furthermore, techniques and probes for analysing MPO expression at the RNA level are now available. This has made possible more extensive studies of MPO expression in a wide range of neoplastic and preneoplastic blood disorders. This review will discuss the fundamental biology of MPO as well as recent developments in our understanding of MPO expression in leukemic cells and cell lines of various lineages.
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Affiliation(s)
- G E Austin
- Atlanta Veterans Affairs Medical Center, Decatur, Georgia 30033
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27
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Rochet JC, Bridger WA. Identification of glutamate 344 as the catalytic residue in the active site of pig heart CoA transferase. Protein Sci 1994; 3:975-81. [PMID: 7915164 PMCID: PMC2142888 DOI: 10.1002/pro.5560030613] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The enzyme CoA transferase (succinyl-CoA:3-ketoacid coenzyme A transferase [3-oxoacid CoA transferase], EC 2.8.3.5) is essential for the metabolism of ketone bodies in the mammalian mitochondrion. It is known that its catalytic mechanism involves the transient thioesterification of an active-site glutamate residue by CoA. As a means of identifying this glutamate within the sequence, we have made use of a fortuitous autolytic fragmentation that occurs at the active site when the enzyme-CoA covalent intermediate is heated. The presence of protease inhibitors has no effect on the extent of cleavage detectable by SDS-PAGE, supporting the view that this fragmentation is indeed autolytic. This fragmentation can be carried out on intact CoA transferase, as well as on a proteolytically nicked but active form of the enzyme. Because the resulting C-terminal fragment is blocked at its N-terminus by a pyroglutamate moiety, it is not amenable to direct sequencing by the Edman degradation method. As an alternative, we have studied a peptide (peptide D) generated specifically by autolysis of the nicked enzyme and predicted to have an N-terminus corresponding to the site of proteolysis and a C-terminus determined by the site of autolysis. This peptide was purified by reversed-phase HPLC and subsequently characterized by electrospray mass spectrometry. We have obtained a mass value for peptide D, from which it can be deduced that glutamate 344, known to be conserved in all sequenced CoA transferases, is the catalytically active amino acid. This information should prove useful to future mutagenesis work aimed at better understanding the active-site structure and catalytic mechanism of CoA transferase.
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Affiliation(s)
- J C Rochet
- Department of Biochemistry, University of Alberta, Edmonton, Canada
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28
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Segelmark M, Baslund B, Wieslander J. Some patients with anti-myeloperoxidase autoantibodies have a C-ANCA pattern. Clin Exp Immunol 1994; 96:458-65. [PMID: 7516271 PMCID: PMC1534554 DOI: 10.1111/j.1365-2249.1994.tb06051.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Rapidly progressive glomerulonephritis with or without other signs of systemic vasculitis is often accompanied by antibodies to myeloperoxidase. Such antibodies normally produce a perinuclear pattern on ethanol-fixed neutrophils (perinuclear anti-neutrophil cytoplasm antibodies (P-ANCA)) at indirect immunofluorescence. We report here sera from three patients that are anti-myeloperoxidase-positive in ELISA that instead produce a cytoplasmic pattern (classical anti-neutrophil cytoplasmic antibodies (C-ANCA)), a pattern normally seen in conjunction with antibodies to proteinase 3. These sera did not react with proteinase 3. For two of the sera the specificity of the anti-myeloperoxidase reaction was confirmed with inhibition-ELISA experiments and with immunoblotting. A mouse anti-myeloperoxidase MoAb that produces a cytoplasmic pattern is also described. Competition ELISA experiments show that this antibody and anti-myeloperoxidase sera with cytoplasmic pattern recognize epitopes that are separate from epitopes recognized by another perinuclear pattern producing anti-myeloperoxidase MoAb. 'Cytoplasmic pattern' epitopes as well as 'perinuclear pattern' epitopes can be found on all three major myeloperoxidase isoforms, after separation by ion exchange chromatography. Affinity chromatography, using the cytoplasmic pattern producing anti-myeloperoxidase monoclonal antibody, shows that the epitope recognized by this MoAb is present on all myeloperoxidase molecules. This epitope is not confined to any special subpopulation. These findings indicate that all myeloperoxidase do not relocate after ethanol fixation, and that C-ANCA and P-ANCA epitopes exist simultaneously on the same myeloperoxidase molecule. We propose that the two immunofluorescence patterns arise due to different availabilities of the epitopes in the microenvironment where myeloperoxidase is present.
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Affiliation(s)
- M Segelmark
- Department of Nephrology, University of Lund, Sweden
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29
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Argüello J, Kaplan J. Glutamate 779, an intramembrane carboxyl, is essential for monovalent cation binding by the Na,K-ATPase. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)37459-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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