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W.j. Ingledew - One of the best experts on this subject based on the ideXlab platform.
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Enzymes of Aerobic respirAtion on iron
1993Co-Authors: R.c. Blake, E.a. Shute, M.m. Greenwood, G.h. Spencer, W.j. IngledewAbstract:AbstrAct BActeriA cApAble of Aerobic respirAtion on ferrous ions Are spreAd throughout eubActeriAl And ArchAebActeriAl phylA. CompArAtive spectroscopic AnAlyses reveAled thAt phylogeneticAlly distinct orgAnisms expressed copious quAntities of spectrAlly distinct redox-Active biomolecules during Autotrophic growth on soluble iron. ThiobAeillus ferrooxidAns, Leptospirillum ferrooxidAns, SulfobAcillus thermosulfidooxidAns , And MetAllosphAerA sedulA possessed iron respirAtory chAins dominAted by A blue copper protein, A novel red Cytochrome, A novel yellow protein, And A novel yellow Cytochrome, respectively. Further investigAtion of eAch type of respirAtory chAin will be necessAry to deduce the AdvAntAges And disAdvAntAges of eAch.
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determinAtion of the ligAnds of the low spin heme of the Cytochrome o ubiquinol oxidAse complex using site directed mutAgenesis
1992Co-Authors: Laura Lemieux, W.j. Ingledew, Melissa W Calhoun, Jeffrey W Thomas, Robert B GennisAbstract:The Cytochrome o complex of EscherichiA coli is A ubiquinol oxidAse which is the predominAnt respirAtory terminAl oxidAse when the bActeriA Are grown under high oxygen tension. The Amino Acid sequences of three of the subunits of this quinol oxidAse reveAl A substAntiAl relAtionship to the AA3-type Cytochrome c oxidAses. The two Cytochrome components (b563.5 And o) And the single copper (CuB) present in the E. coli quinol oxidAse AppeAr to be equivAlent to Cytochrome A, Cytochrome A3, And CuB of the AA3-type Cytochrome c oxidAses, respectively. These three prosthetic groups Are All locAted within subunit I of the oxidAse. Sequence Alignments indicAte only six totAlly conserved histidine residues Among All known sequences of subunit I of the Cytochrome c oxidAses of vArious species plus the E. coli quinol oxidAse. Site-directed mutAgenesis hAs been used to chAnge eAch of these totAlly conserved histidines with the presumption thAt two of these six must ligAte to the low spin Cytochrome center of the E. coli oxidAse. The presence of the low spin Cytochrome b563.5 component of the oxidAse cAn be evAluAted both by visible AbsorbAnce properties And by its EPR spectrum. The results unAmbiguously indicAte thAt His-106 And His-421 Are the ligAnds of the six-coordinAte low spin Cytochrome b563.5. Although the dAtA Are not definitive in mAking AdditionAl metAl ligAtion Assignments of the remAining four totAlly conserved histidines, A reAsonAble model is suggested for the structure of the cAtAlytic core of the Cytochrome o complex And, by extrApolAtion, of Cytochrome c oxidAse.
Hideyoshi Yokosawa - One of the best experts on this subject based on the ideXlab platform.
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zymosAn induces production of superoxide Anions by hemocytes of the solitAry AscidiAn hAlocynthiA roretzi
2002Co-Authors: Kaoru Azumi, Futoshi Kuribayashi, Shiro Kanegasaki, Hideyoshi YokosawaAbstract:ReActive oxygen intermediAtes (ROIs), including superoxide Anions And hydrogen peroxide, Are generAted by phAgocytes in invertebrAtes, As well As in vertebrAtes. To understAnd the moleculAr mechAnisms underlying the generAtion of ROIs by hemocytes of the solitAry AscidiAn HAlocynthiA roretzi, we estAblished A method of meAsuring ROIs using luminol-dependent chemiluminescence (LDCL). LDCL AnAlyses reveAled thAt both zymosAn And phorbol myristAte AcetAte (PMA), but not lipopolysAcchAride, b1,3-glucAn, or formylpeptide, induced the generAtion of ROIs by H. roretzi hemocytes. The zymosAn-induced LDCL wAs mArkedly inhibited by the Addition of superoxide dismutAse (SOD) or H. roretzi plAsmA. A cAlcium-chelAting reAgent, BAPTA-AM, completely inhibited the zymosAn-induced LDCL. On the other hAnd, the PMA-induced LDCL wAs only slightly inhibited by the Addition of SOD or BAPTA-AM. Spectroscopic AnAlysis At A low temperAture reveAled thAt H. roretzi hemocytes hAd Absorption spectrA specific for type b Cytochrome, A component of the NADPH oxidAse complex in mAmmAliAn phAgocytes. These results strongly suggest thAt H. roretzi hemocytes generAte superoxide Anions upon phAgocytosis And thAt intrAcellulAr cAlcium ions And possibly An NADPH oxidAse complex Are involved in their generAtion by H. roretzi hemocytes. 2002 Elsevier Science Inc. All rights reserved.
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zymosAn induces production of superoxide Anions by hemocytes of the solitAry AscidiAn hAlocynthiA roretzi
2002Co-Authors: Kaoru Azumi, Futoshi Kuribayashi, Shiro Kanegasaki, Hideyoshi YokosawaAbstract:ReActive oxygen intermediAtes (ROIs), including superoxide Anions And hydrogen peroxide, Are generAted by phAgocytes in invertebrAtes, As well As in vertebrAtes. To understAnd the moleculAr mechAnisms underlying the generAtion of ROIs by hemocytes of the solitAry AscidiAn HAlocynthiA roretzi, we estAblished A method of meAsuring ROIs using luminol-dependent chemiluminescence (LDCL). LDCL AnAlyses reveAled thAt both zymosAn And phorbol myristAte AcetAte (PMA), but not lipopolysAcchAride, b1,3-glucAn, or formylpeptide, induced the generAtion of ROIs by H. roretzi hemocytes. The zymosAn-induced LDCL wAs mArkedly inhibited by the Addition of superoxide dismutAse (SOD) or H. roretzi plAsmA. A cAlcium-chelAting reAgent, BAPTA-AM, completely inhibited the zymosAn-induced LDCL. On the other hAnd, the PMA-induced LDCL wAs only slightly inhibited by the Addition of SOD or BAPTA-AM. Spectroscopic AnAlysis At A low temperAture reveAled thAt H. roretzi hemocytes hAd Absorption spectrA specific for type b Cytochrome, A component of the NADPH oxidAse complex in mAmmAliAn phAgocytes. These results strongly suggest thAt H. roretzi hemocytes generAte superoxide Anions upon phAgocytosis And thAt intrAcellulAr cAlcium ions And possibly An NADPH oxidAse complex Are involved in their generAtion by H. roretzi hemocytes. 2002 Elsevier Science Inc. All rights reserved.
Rafael Radi - One of the best experts on this subject based on the ideXlab platform.
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differentiAl inhibitory Action of nitric oxide And peroxynitrite on mitochondriAl electron trAnsport
1996Co-Authors: Adriana Cassina, Rafael RadiAbstract:AbstrAct VArious Authors hAve suggested thAt nitric oxide ( • NO) exerts cytotoxic effects through the inhibition of cellulAr respirAtion. Indeed, in intAct cells • NO inhibits glutAmAte–mAlAte (complex I) As well As succinAte (complex II)-supported mitochondriAl electron trAnsport, without Affecting TMPD/AscorbAte (complex IV)-dependent respirAtion. However, experiments in our lAb using isolAted rAt heArt mitochondriA indicAted thAt Authentic • NO inhibited electron trAnsport mostly by reversible binding to the terminAl oxidAse, Cytochrome A 3 , hAving A less significAnt effect on complex II- And no effect on complex I-electron trAnsport components. The inhibitory Action of • NO wAs more profound At lower oxygen tensions And resulted in A differentiAl spectrA similAr to thAt observed in dithionite-treAted mitochondriA. On the other hAnd, continuous fluxes of • NO plus superoxide (O •− 2 ), which leAd to formAtion of micromolAr steAdy-stAte levels of peroxynitrite Anion (ONOO − ), cAused A strong inhibition of complex I- And complex II-dependent mitochondriAl oxygen consumption And significAntly inhibited the Activities of succinAte dehydrogenAse And ATPAse, without Affecting complex IV-dependent respirAtion And Cytochrome c oxidAse Activity. In conclusion, even though nitric oxide cAn directly cAuse A trAnsient inhibition of electron trAnsport, the inhibition pAttern of mitochondriAl respirAtion observed in the presence of peroxynitrite is the one thAt closely resembles thAt found secondAry to • NO interActions with intAct cells And strongly points to peroxynitrite As the ultimAte reActive intermediAte Accounting for nitric oxide-dependent inActivAtion of electron trAnsport components And ATPAse in living cells And tissues.
Charles L Hoppel - One of the best experts on this subject based on the ideXlab platform.
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decreAsed Activities of ubiquinol ferriCytochrome c oxidoreductAse complex iii And ferroCytochrome c oxygen oxidoreductAse complex iv in liver mitochondriA from rAts with hydroxycobAlAmin c lActAm induced methylmAlonic AciduriA
1991Co-Authors: Stephan Krahenbuhl, Mei Chang, Eric P Brass, Charles L HoppelAbstract:AbstrAct RAts treAted with hydroxycobAlAmin[c-lActAm] (HCCL), A cobAlAmin AnAlogue thAt induces methylmAlonic AciduriA, hAve increAsed hepAtic mitochondriAl content And increAsed oxidAtive metAbolism of pyruvAte And pAlmitAte per hepAtocyte. The present studies were undertAken to chArActerize oxidAtive metAbolism in isolAted liver mitochondriA from rAts treAted with HCCL. After 5-6 weeks, stAte 3 oxidAtion rAtes for diverse substrAtes Are reduced in mitochondriA from HCCL-treAted rAts. SimilAr reductions of mitochondriAl oxidAtion rAtes Are obtAined with dinitrophenol-uncoupled mitochondriA excluding defective phosphorylAtion As A cAuse for the observed decreAse in mitochondriAl oxidAtion. The Activities of mitochondriAl oxidAses Are reduced in HCCL-treAted rAts And demonstrAte A defect in complex IV. InvestigAtion of the complexes of the respirAtory chAin reveAls A 32% decreAse of ubiquinol:ferriCytochrome c oxidoreductAse (complex III) Activity And A 72% decreAse of ferroCytochrome c:oxygen oxidoreductAse (complex IV) Activity in mitochondriA from 5-6-week HCCL-treAted rAts As compAred with controls. Liver mitochondriA from HCCL-treAted rAts Also demonstrAte decreAsed Cytochrome content per mg of mitochondriAl protein (25% decreAse of Cytochrome b And 52% decreAse of Cytochrome A + A3 As compAred with control rAts). The HCCL-treAted rAt represents An AnimAl model for the study of the consequences of respirAtory chAin defects in liver mitochondriA.
Chris E Cooper - One of the best experts on this subject based on the ideXlab platform.
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interAction of peroxynitrite with mitochondriAl Cytochrome oxidAse cAtAlytic production of nitric oxide And irreversible inhibition of enzyme Activity
1998Co-Authors: Martyn A Sharpe, Chris E CooperAbstract:Purified mitochondriAl Cytochrome c oxidAse cAtAlyzes the conversion of peroxynitrite to nitric oxide (NO). This reAction is cyAnide-sensitive, indicAting thAt the binucleAr heme A3/CuB center is the cAtAlytic site. NO production cAuses A reversible inhibition of turnover, chArActerized by formAtion of the Cytochrome A3 nitrosyl complex. In Addition, peroxynitrite cAuses irreversible inhibition of Cytochrome oxidAse, chArActerized by A decreAsed VmAx And A rAised Km for oxygen. Under these conditions, the redox stAte of Cytochrome A is elevAted, indicAting inhibition of electron trAnsfer And/or oxygen reduction reActions subsequent to this center. The lipid bilAyer is no bArrier to these peroxynitrite effects, As NO production And irreversible enzyme inhibition were Also observed in Cytochrome oxidAse proteoliposomes. Addition of 50 microM peroxynitrite to 10 microM fully oxidized enzyme induced spectrAl chAnges chArActeristic of the formAtion of ferryl Cytochrome A3, pArtiAl reduction of Cytochrome A, And irreversible dAmAge to the CuA site. Higher concentrAtions of peroxynitrite (250 microM) cAuse heme degrAdAtion. In the fully reduced enzyme, peroxynitrite cAuses A red shift in the opticAl spectrum of both Cytochromes A And A3, resulting in A symmetricAl peAk in the visible region. Therefore, peroxynitrite cAn both modify And degrAde the metAl centers of Cytochrome oxidAse.
