Modulation of Mitochondrial Function by Hydrogen Peroxide

Abstract

During normal cellular metabolism, mitochondrial electron transport results in the formation of superoxide anion (O⨪2) and subsequently hydrogen peroxide (H2O2). Because H2O2 increases in concentration under certain physiologic and pathophysiologic conditions and can oxidatively modify cellular components, it is critical to understand the response of mitochondria to H2O2. In the present study, treatment of isolated rat heart mitochondria with H2O2 resulted in a decline and subsequent recovery of state 3 NADH-linked respiration. Alterations in NADH levels induced by H2O2 closely paralleled changes in the rate of state 3 respiration. Assessment of electron transport chain complexes and Krebs cycle enzymes revealed that α-ketoglutarate dehydrogenase (KGDH), succinate dehydrogenase (SDH), and aconitase were susceptible to H2O2 inactivation. Of particular importance, KGDH and SDH activity returned to control levels, concurrent with the recovery of state 3 respiration. Inactivation is not because of direct interaction of H2O2 with KGDH and SDH. In addition, removal of H2O2alone is not sufficient for reactivation. Enzyme activity does not recover unless mitochondria remain intact. The sensitivity of KGDH and SDH to H2O2-mediated inactivation and the reversible nature of inactivation suggest a potential role for H2O2 in the regulation of KGDH and SDH. During normal cellular metabolism, mitochondrial electron transport results in the formation of superoxide anion (O⨪2) and subsequently hydrogen peroxide (H2O2). Because H2O2 increases in concentration under certain physiologic and pathophysiologic conditions and can oxidatively modify cellular components, it is critical to understand the response of mitochondria to H2O2. In the present study, treatment of isolated rat heart mitochondria with H2O2 resulted in a decline and subsequent recovery of state 3 NADH-linked respiration. Alterations in NADH levels induced by H2O2 closely paralleled changes in the rate of state 3 respiration. Assessment of electron transport chain complexes and Krebs cycle enzymes revealed that α-ketoglutarate dehydrogenase (KGDH), succinate dehydrogenase (SDH), and aconitase were susceptible to H2O2 inactivation. Of particular importance, KGDH and SDH activity returned to control levels, concurrent with the recovery of state 3 respiration. Inactivation is not because of direct interaction of H2O2 with KGDH and SDH. In addition, removal of H2O2alone is not sufficient for reactivation. Enzyme activity does not recover unless mitochondria remain intact. The sensitivity of KGDH and SDH to H2O2-mediated inactivation and the reversible nature of inactivation suggest a potential role for H2O2 in the regulation of KGDH and SDH. 4-morpholinepropanesulfonic acid α-ketoglutarate dehydrogenase succinate dehydrogenase The four-electron reduction of O2 to two molecules of H2O represents the final step in mitochondrial electron transport. Chance and Williams (1Chance B. Williams G.R. Advan. Enzymol. Relat. Subj. Biochem. 1956; 17: 65-134PubMed Google Scholar) first reported, however, that as much as 1–2% of oxygen consumed during mitochondrial respiration undergoes incomplete reduction to superoxide anion (O⨪2). Produced at the NADH-coenzyme Q reductase (Complex I) and cytochromec oxidase (Complex III) sites of the electron transport chain, superoxide is rapidly converted to hydrogen peroxide (H2O2) by superoxide dismutase (1Chance B. Williams G.R. Advan. Enzymol. Relat. Subj. Biochem. 1956; 17: 65-134PubMed Google Scholar, 2Cadenas E. Boveris A. Ragan C.I. Stoppani A.O. Arch. Biochem. Biophys. 1977; 180: 248-257Crossref PubMed Scopus (687) Google Scholar, 3Cadenas E. Boveris A. Biochem. J. 1980; 188: 31-37Crossref PubMed Scopus (235) Google Scholar, 4Turrens J.F. Boveris A. Biochem. J. 1980; 191: 421-427Crossref PubMed Scopus (1350) Google Scholar, 5Nohl H. Hegner D. Eur. J. Biochem. 1978; 82: 563-567Crossref PubMed Scopus (468) Google Scholar, 6Nohl H. Breuninger V. Hegner D. Eur. J. Biochem. 1978; 90: 385-390Crossref PubMed Scopus (144) Google Scholar, 7Cadenas E. Davies K.J. Free Radic. Biol. Med. 2000; 29: 222-230Crossref PubMed Scopus (2329) Google Scholar, 8Boveris A. Chance B. Biochem. J. 1973; 134: 707-716Crossref PubMed Scopus (2076) Google Scholar, 9Loschen G. Azzi A. Flohe L. FEBS Lett. 1973; 33: 84-87Crossref PubMed Scopus (157) Google Scholar, 10Boveris A. Cadenas E. FEBS Lett. 1975; 54: 311-314Crossref PubMed Scopus (329) Google Scholar). Interaction of H2O2 with metal ions, such as Fe2+, can result in the formation of metal-centered oxygen radicals and hydroxyl radical (OH⋅). These species are highly reactive and can oxidatively damage protein, lipids, and DNA (11Beckman J. Biol. PubMed Scopus Google Scholar, J. Biol. PubMed Scopus Google Scholar, H. H. Free Radic. Biol. Med. PubMed Scopus Google Scholar, PubMed Scopus Google Scholar). the and removal of oxygen mitochondria a of enzymes and does mitochondrial radical of radicals the of and to is by oxygen radicals a role in the regulation of oxygen radicals in concentration and reversible with that the rate of mitochondrial radical increases as a result of electron transport (1Chance B. Williams G.R. Advan. Enzymol. Relat. Subj. Biochem. 1956; 17: 65-134PubMed Google Scholar, 2Cadenas E. Boveris A. Ragan C.I. Stoppani A.O. Arch. Biochem. Biophys. 1977; 180: 248-257Crossref PubMed Scopus (687) Google Scholar, 3Cadenas E. Boveris A. Biochem. J. 1980; 188: 31-37Crossref PubMed Scopus (235) Google Scholar, 4Turrens J.F. Boveris A. Biochem. J. 1980; 191: 421-427Crossref PubMed Scopus (1350) Google Scholar, 5Nohl H. Hegner D. Eur. J. Biochem. 1978; 82: 563-567Crossref PubMed Scopus (468) Google Scholar, 6Nohl H. Breuninger V. Hegner D. Eur. J. Biochem. 1978; 90: 385-390Crossref PubMed Scopus (144) Google Scholar, 7Cadenas E. Davies K.J. Free Radic. Biol. Med. 2000; 29: 222-230Crossref PubMed Scopus (2329) Google Scholar, 8Boveris A. Chance B. Biochem. J. 1973; 134: 707-716Crossref PubMed Scopus (2076) Google Scholar, 9Loschen G. Azzi A. Flohe L. FEBS Lett. 1973; 33: 84-87Crossref PubMed Scopus (157) Google Scholar, 10Boveris A. Cadenas E. FEBS Lett. 1975; 54: 311-314Crossref PubMed Scopus (329) Google Scholar). for under certain conditions of that result in of complexes G. G. J. Biol. PubMed Google Scholar, J. 82: PubMed Scopus Google Scholar, A. PubMed Scopus Google Scholar, A. PubMed Scopus Google Scholar, H. H. A. A. PubMed Scopus Google Scholar, H. A. G. J. PubMed Scopus Google Scholar). The of H2O2 and radicals is the activity and concentration of a of and are of the concentration of oxygen radicals and H2O2 in response to in species to with and modify activity J. Biol. PubMed Scopus Google Scholar). in the of radical it is that to can the activity of certain for in that are reversible and response is oxygen radicals are to molecules of to the potential role of in the regulation of mitochondrial mitochondria were isolated rat heart and with of H2O2 that result in reversible in the rate of state 3 respiration. The of of electron transport chain, and Krebs cycle enzymes were as a of and of are that that levels are and of respiration is Krebs cycle enzymes in of levels and the of certain of enzymes to control H2O2-mediated inactivation of enzymes that mitochondria remain intact. These results are in of the potential role of in the regulation of mitochondrial and suggest to radicals and H2O2 the of the damage is however, that by of the to J. Biol. PubMed Scopus Google Scholar) and in concentration in response to species certain of molecules G. J. Biol. PubMed Google Scholar, J. Biol. PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, J. Biol. PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, H. H. J. 17: PubMed Scopus Google Scholar, H. H. H. Biol. 2000; PubMed Scopus Google Scholar) Arch. Biochem. Biophys. 2000; PubMed Scopus Google Scholar, FEBS Lett. 2000; PubMed Scopus Google Scholar, A. Free Radic. Biol. Med. PubMed Scopus Google Scholar, H. H. PubMed Scopus Google Scholar, Med. PubMed Scopus Google Scholar). that of respiration and are in a reversible of mitochondria with H2O2. 3 the of NADH for electron transport. These results are in with for rat mitochondria with J. Biochem. PubMed Scopus Google Scholar). of electron transport chain complexes and Krebs cycle enzymes revealed inactivation of and the levels of NADH for of mitochondrial respiration not by of for removal of H2O2 by of NADH In to the of SDH and KGDH in with of respiration. results that H2O2 SDH and KGDH by the of the These results suggest that in the rate of H2O2 to mitochondrial a by Inactivation of KGDH and SDH for electron transport and of and H2O2. reversible of KGDH and SDH a in oxygen radical in H2O2 to electron transport and for and electron transport mitochondrial of (1Chance B. Williams G.R. Advan. Enzymol. Relat. Subj. Biochem. 1956; 17: 65-134PubMed Google Scholar, 2Cadenas E. Boveris A. Ragan C.I. Stoppani A.O. Arch. Biochem. Biophys. 1977; 180: 248-257Crossref PubMed Scopus (687) Google Scholar, 3Cadenas E. Boveris A. Biochem. J. 1980; 188: 31-37Crossref PubMed Scopus (235) Google Scholar, 4Turrens J.F. Boveris A. Biochem. J. 1980; 191: 421-427Crossref PubMed Scopus (1350) Google Scholar, 5Nohl H. Hegner D. Eur. J. Biochem. 1978; 82: 563-567Crossref PubMed Scopus (468) Google Scholar, 6Nohl H. Breuninger V. Hegner D. Eur. J. Biochem. 1978; 90: 385-390Crossref PubMed Scopus (144) Google Scholar, 7Cadenas E. Davies K.J. Free Radic. Biol. Med. 2000; 29: 222-230Crossref PubMed Scopus (2329) Google Scholar, 8Boveris A. Chance B. Biochem. J. 1973; 134: 707-716Crossref PubMed Scopus (2076) Google Scholar, 9Loschen G. Azzi A. Flohe L. FEBS Lett. 1973; 33: 84-87Crossref PubMed Scopus (157) Google Scholar, 10Boveris A. Cadenas E. FEBS Lett. 1975; 54: 311-314Crossref PubMed Scopus (329) Google Scholar). in the of KGDH and SDH under conditions the for NADH and is as the for of H2O2 to in of SDH and KGDH and the of of electron transport. potential for H2O2 the mitochondria are not inactivation of KGDH and SDH oxygen radical under conditions of and during normal In study, of H2O2 during conditions of inactivation of KGDH and SDH at the concentration of H2O2 the response of mitochondria to H2O2 under is that H2O2 and certain oxygen radicals cellular that H2O2 is of by H2O2 and oxygen radicals reversible of and in the molecules and G. J. Biol. PubMed Google Scholar, J. Biol. PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, J. Biol. PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, H. H. J. 17: PubMed Scopus Google Scholar, H. H. H. Biol. 2000; PubMed Scopus Google Scholar) Arch. Biochem. Biophys. 2000; PubMed Scopus Google Scholar, FEBS Lett. 2000; PubMed Scopus Google Scholar, A. Free Radic. Biol. Med. PubMed Scopus Google Scholar, H. H. PubMed Scopus Google Scholar, Med. PubMed Scopus Google Scholar). the role of H2O2 in mitochondria it is to the SDH and KGDH are and Inactivation of SDH and KGDH is not because of direct interaction with H2O2. In addition, removal of H2O2 is not sufficient for reactivation. These results that SDH and KGDH are to the of the are by activity are the potential role of the and the of SDH and KGDH to reversible is under the conditions of the to SDH and KGDH were of the concentration of H2O2 with the sensitivity of enzymes to a of reversible results of in to KGDH and H2O2 is to with in inactivation. The of aconitase to radical inactivation is in with A. J. Biol. PubMed Google Scholar, D. J. PubMed Google Scholar, J. Biochem. J. PubMed Scopus Google Scholar, J.F. J. Biol. PubMed Google Scholar, J. Biol. PubMed Google Scholar, J. Biol. PubMed Scopus Google Scholar, H. PubMed Scopus Google Scholar, A. PubMed Scopus Google Scholar, H. J. Biol. PubMed Google Scholar, H. J. Biol. PubMed Google Scholar, J. J. Biol. PubMed Google Scholar). it that mitochondrial aconitase is with superoxide (O⨪2) the is to in the of and H2O2 J. B. J. Biol. 2000; PubMed Scopus Google Scholar). the revealed that removal of and the of to D. J. PubMed Google Scholar, J. Biol. PubMed Scopus Google H. PubMed Scopus Google Scholar, H. J. Biol. PubMed Google Scholar, H. J. Biol. PubMed Google Scholar, J. J. Biol. PubMed Google Scholar, J. B. J. Biol. 2000; PubMed Scopus Google Scholar). under the conditions of mitochondria were isolated in a that of aconitase the of D. J. PubMed Google J. Biol. PubMed Google Scholar). results that the of H2O2 inactivation results in recovery of aconitase as J. B. J. Biol. 2000; PubMed Scopus Google under in conditions the activity of aconitase is by mitochondrial These results the to the potential for of inactivation. Because of incomplete removal of the removal of for the reversible nature of inactivation In the present study, aconitase activity the rate of state 3 respiration is with α-ketoglutarate as a aconitase activity is not for the of that the of aconitase inactivation and to state 3 that result in the of the Krebs the by mitochondria to a of mitochondrial in the of mitochondria to changes in and in a with In study, that mitochondrial respiration and the of mitochondrial enzymes are by the of H2O2 in a reversible suggest a role for radicals in regulation of mitochondrial direct of that to In addition, to the of and H2O2 a of of the and radical as as of mitochondrial respiration and KGDH activity in H. Biophys. PubMed Scopus Google J. PubMed Scopus Google Scholar, PubMed Scopus Google and G. G. J. Biol. PubMed Google Scholar, J. 82: PubMed Scopus Google Scholar, A. PubMed Scopus Google Scholar, A. PubMed Scopus Google Scholar, H. H. A. A. PubMed Scopus Google Scholar, H. A. G. J. PubMed Scopus Google Scholar). of the radical and mitochondrial to by radicals to the of The four-electron reduction of O2 to two molecules of H2O represents the final step in mitochondrial electron transport. Chance and Williams (1Chance B. Williams G.R. Advan. Enzymol. Relat. Subj. Biochem. 1956; 17: 65-134PubMed Google Scholar) first reported, however, that as much as 1–2% of oxygen consumed during mitochondrial respiration undergoes incomplete reduction to superoxide anion (O⨪2). Produced at the NADH-coenzyme Q reductase (Complex I) and cytochromec oxidase (Complex III) sites of the electron transport chain, superoxide is rapidly converted to hydrogen peroxide (H2O2) by superoxide dismutase (1Chance B. Williams G.R. Advan. Enzymol. Relat. Subj. Biochem. 1956; 17: 65-134PubMed Google Scholar, 2Cadenas E. Boveris A. Ragan C.I. Stoppani A.O. Arch. Biochem. Biophys. 1977; 180: 248-257Crossref PubMed Scopus (687) Google Scholar, 3Cadenas E. Boveris A. Biochem. J. 1980; 188: 31-37Crossref PubMed Scopus (235) Google Scholar, 4Turrens J.F. Boveris A. Biochem. J. 1980; 191: 421-427Crossref PubMed Scopus (1350) Google Scholar, 5Nohl H. Hegner D. Eur. J. Biochem. 1978; 82: 563-567Crossref PubMed Scopus (468) Google Scholar, 6Nohl H. Breuninger V. Hegner D. Eur. J. Biochem. 1978; 90: 385-390Crossref PubMed Scopus (144) Google Scholar, 7Cadenas E. Davies K.J. Free Radic. Biol. Med. 2000; 29: 222-230Crossref PubMed Scopus (2329) Google Scholar, 8Boveris A. Chance B. Biochem. J. 1973; 134: 707-716Crossref PubMed Scopus (2076) Google Scholar, 9Loschen G. Azzi A. Flohe L. FEBS Lett. 1973; 33: 84-87Crossref PubMed Scopus (157) Google Scholar, 10Boveris A. Cadenas E. FEBS Lett. 1975; 54: 311-314Crossref PubMed Scopus (329) Google Scholar). Interaction of H2O2 with metal ions, such as Fe2+, can result in the formation of metal-centered oxygen radicals and hydroxyl radical (OH⋅). These species are highly reactive and can oxidatively damage protein, lipids, and DNA (11Beckman J. Biol. PubMed Scopus Google Scholar, J. Biol. PubMed Scopus Google Scholar, H. H. Free Radic. Biol. Med. PubMed Scopus Google Scholar, PubMed Scopus Google Scholar). the and removal of oxygen mitochondria a of enzymes and does mitochondrial radical of radicals the of and to is by oxygen radicals a role in the regulation of oxygen radicals in concentration and reversible with that the rate of mitochondrial radical increases as a result of electron transport (1Chance B. Williams G.R. Advan. Enzymol. Relat. Subj. Biochem. 1956; 17: 65-134PubMed Google Scholar, 2Cadenas E. Boveris A. Ragan C.I. Stoppani A.O. Arch. Biochem. Biophys. 1977; 180: 248-257Crossref PubMed Scopus (687) Google Scholar, 3Cadenas E. Boveris A. Biochem. J. 1980; 188: 31-37Crossref PubMed Scopus (235) Google Scholar, 4Turrens J.F. Boveris A. Biochem. J. 1980; 191: 421-427Crossref PubMed Scopus (1350) Google Scholar, 5Nohl H. Hegner D. Eur. J. Biochem. 1978; 82: 563-567Crossref PubMed Scopus (468) Google Scholar, 6Nohl H. Breuninger V. Hegner D. Eur. J. Biochem. 1978; 90: 385-390Crossref PubMed Scopus (144) Google Scholar, 7Cadenas E. Davies K.J. Free Radic. Biol. Med. 2000; 29: 222-230Crossref PubMed Scopus (2329) Google Scholar, 8Boveris A. Chance B. Biochem. J. 1973; 134: 707-716Crossref PubMed Scopus (2076) Google Scholar, 9Loschen G. Azzi A. Flohe L. FEBS Lett. 1973; 33: 84-87Crossref PubMed Scopus (157) Google Scholar, 10Boveris A. Cadenas E. FEBS Lett. 1975; 54: 311-314Crossref PubMed Scopus (329) Google Scholar). for under certain conditions of that result in of complexes G. G. J. Biol. PubMed Google Scholar, J. 82: PubMed Scopus Google Scholar, A. PubMed Scopus Google Scholar, A. PubMed Scopus Google Scholar, H. H. A. A. PubMed Scopus Google Scholar, H. A. G. J. PubMed Scopus Google Scholar). The of H2O2 and radicals is the activity and concentration of a of and are of the concentration of oxygen radicals and H2O2 in response to in species to with and modify activity J. Biol. PubMed Scopus Google Scholar). in the of radical it is that to can the activity of certain for in that are reversible and response is oxygen radicals are to molecules The of to the potential role of in the regulation of mitochondrial mitochondria were isolated rat heart and with of H2O2 that result in reversible in the rate of state 3 respiration. The of of electron transport chain, and Krebs cycle enzymes were as a of and of are that that levels are and of respiration is Krebs cycle enzymes in of levels and the of certain of enzymes to control H2O2-mediated inactivation of enzymes that mitochondria remain intact. These results are in of the potential role of in the regulation of mitochondrial and suggest to radicals and H2O2 the of the damage is however, that by of the to J. Biol. PubMed Scopus Google Scholar) and in concentration in response to species certain of molecules G. J. Biol. PubMed Google Scholar, J. Biol. PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, J. Biol. PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, H. H. J. 17: PubMed Scopus Google Scholar, H. H. H. Biol. 2000; PubMed Scopus Google Scholar) Arch. Biochem. Biophys. 2000; PubMed Scopus Google Scholar, FEBS Lett. 2000; PubMed Scopus Google Scholar, A. Free Radic. Biol. Med. PubMed Scopus Google Scholar, H. H. PubMed Scopus Google Scholar, Med. PubMed Scopus Google Scholar). that of respiration and are in a reversible of mitochondria with H2O2. 3 the of NADH for electron transport. These results are in with for rat mitochondria with J. Biochem. PubMed Scopus Google Scholar). of electron transport chain complexes and Krebs cycle enzymes revealed inactivation of and the levels of NADH for of mitochondrial respiration not by of for removal of H2O2 by of NADH In to the of SDH and KGDH in with of respiration. results that H2O2 SDH and KGDH by the of the These results suggest that in the rate of H2O2 to mitochondrial a by Inactivation of KGDH and SDH for electron transport and of and H2O2. reversible of KGDH and SDH a in oxygen radical in H2O2 to electron transport and for and electron transport mitochondrial of (1Chance B. Williams G.R. Advan. Enzymol. Relat. Subj. Biochem. 1956; 17: 65-134PubMed Google Scholar, 2Cadenas E. Boveris A. Ragan C.I. Stoppani A.O. Arch. Biochem. Biophys. 1977; 180: 248-257Crossref PubMed Scopus (687) Google Scholar, 3Cadenas E. Boveris A. Biochem. J. 1980; 188: 31-37Crossref PubMed Scopus (235) Google Scholar, 4Turrens J.F. Boveris A. Biochem. J. 1980; 191: 421-427Crossref PubMed Scopus (1350) Google Scholar, 5Nohl H. Hegner D. Eur. J. Biochem. 1978; 82: 563-567Crossref PubMed Scopus (468) Google Scholar, 6Nohl H. Breuninger V. Hegner D. Eur. J. Biochem. 1978; 90: 385-390Crossref PubMed Scopus (144) Google Scholar, 7Cadenas E. Davies K.J. Free Radic. Biol. Med. 2000; 29: 222-230Crossref PubMed Scopus (2329) Google Scholar, 8Boveris A. Chance B. Biochem. J. 1973; 134: 707-716Crossref PubMed Scopus (2076) Google Scholar, 9Loschen G. Azzi A. Flohe L. FEBS Lett. 1973; 33: 84-87Crossref PubMed Scopus (157) Google Scholar, 10Boveris A. Cadenas E. FEBS Lett. 1975; 54: 311-314Crossref PubMed Scopus (329) Google Scholar). in the of KGDH and SDH under conditions the for NADH and is as the for of H2O2 to in of SDH and KGDH and the of of electron transport. potential for H2O2 the mitochondria are not inactivation of KGDH and SDH oxygen radical under conditions of and during normal In study, of H2O2 during conditions of inactivation of KGDH and SDH at the concentration of H2O2 the response of mitochondria to H2O2 under is that H2O2 and certain oxygen radicals cellular that H2O2 is of by H2O2 and oxygen radicals reversible of and in the molecules and G. J. Biol. PubMed Google Scholar, J. Biol. PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, J. Biol. PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, H. H. J. 17: PubMed Scopus Google Scholar, H. H. H. Biol. 2000; PubMed Scopus Google Scholar) Arch. Biochem. Biophys. 2000; PubMed Scopus Google Scholar, FEBS Lett. 2000; PubMed Scopus Google Scholar, A. Free Radic. Biol. Med. PubMed Scopus Google Scholar, H. H. PubMed Scopus Google Scholar, Med. PubMed Scopus Google Scholar). the role of H2O2 in mitochondria it is to the SDH and KGDH are and Inactivation of SDH and KGDH is not because of direct interaction with H2O2. In addition, removal of H2O2 is not sufficient for reactivation. These results that SDH and KGDH are to the of the are by activity are the potential role of the and the of SDH and KGDH to reversible is under the conditions of the to SDH and KGDH were of the concentration of H2O2 with the sensitivity of enzymes to a of reversible results of in to KGDH and H2O2 is to with in inactivation. The of aconitase to radical inactivation is in with A. J. Biol. PubMed Google Scholar, D. J. PubMed Google Scholar, J. Biochem. J. PubMed Scopus Google Scholar, J.F. J. Biol. PubMed Google Scholar, J. Biol. PubMed Google Scholar, J. Biol. PubMed Scopus Google Scholar, H. PubMed Scopus Google Scholar, A. PubMed Scopus Google Scholar, H. J. Biol. PubMed Google Scholar, H. J. Biol. PubMed Google Scholar, J. J. Biol. PubMed Google Scholar). it that mitochondrial aconitase is with superoxide (O⨪2) the is to in the of and H2O2 J. B. J. Biol. 2000; PubMed Scopus Google Scholar). the revealed that removal of and the of to D. J. PubMed Google Scholar, J. Biol. PubMed Scopus Google H. PubMed Scopus Google Scholar, H. J. Biol. PubMed Google Scholar, H. J. Biol. PubMed Google Scholar, J. J. Biol. PubMed Google Scholar, J. B. J. Biol. 2000; PubMed Scopus Google Scholar). under the conditions of mitochondria were isolated in a that of aconitase the of D. J. PubMed Google J. Biol. PubMed Google Scholar). results that the of H2O2 inactivation results in recovery of aconitase as J. B. J. Biol. 2000; PubMed Scopus Google under in conditions the activity of aconitase is by mitochondrial These results the to the potential for of inactivation. Because of incomplete removal of the removal of for the reversible nature of inactivation In the present study, aconitase activity the rate of state 3 respiration is with α-ketoglutarate as a aconitase activity is not for the of that the of aconitase inactivation and to state 3 that result in the of the Krebs the by mitochondria to a of mitochondrial in the of mitochondria to changes in and in a with In study, that mitochondrial respiration and the of mitochondrial enzymes are by the of H2O2 in a reversible suggest a role for radicals in regulation of mitochondrial direct of that to In addition, to the of and H2O2 a of of the and radical as as of mitochondrial respiration and KGDH activity in H. Biophys. PubMed Scopus Google J. PubMed Scopus Google Scholar, PubMed Scopus Google and G. G. J. Biol. PubMed Google Scholar, J. 82: PubMed Scopus Google Scholar, A. PubMed Scopus Google Scholar, A. PubMed Scopus Google Scholar, H. H. A. A. PubMed Scopus Google Scholar, H. A. G. J. PubMed Scopus Google Scholar). of the radical and mitochondrial to by radicals to the of radicals and H2O2 the of the damage is however, that by of the to J. Biol. PubMed Scopus Google Scholar) and in concentration in response to species certain of molecules G. J. Biol. PubMed Google Scholar, J. Biol. PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, J. Biol. PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, H. H. J. 17: PubMed Scopus Google Scholar, H. H. H. Biol. 2000; PubMed Scopus Google Scholar) Arch. Biochem. Biophys. 2000; PubMed Scopus Google Scholar, FEBS Lett. 2000; PubMed Scopus Google Scholar, A. Free Radic. Biol. Med. PubMed Scopus Google Scholar, H. H. PubMed Scopus Google Scholar, Med. PubMed Scopus Google Scholar). that of respiration and are in a reversible of mitochondria with H2O2. 3 the of NADH for electron transport. These results are in with for rat mitochondria with J. Biochem. PubMed Scopus Google Scholar). of electron transport chain complexes and Krebs cycle enzymes revealed inactivation of and the levels of NADH for of mitochondrial respiration not by of for removal of H2O2 by of NADH In to the of SDH and KGDH in with of respiration. results that H2O2 SDH and KGDH by the of the These results suggest that in the rate of H2O2 to mitochondrial a by Inactivation of KGDH and SDH for electron transport and of and H2O2. reversible of KGDH and SDH a in oxygen radical in H2O2 to electron transport and for and electron transport mitochondrial of (1Chance B. Williams G.R. Advan. Enzymol. Relat. Subj. Biochem. 1956; 17: 65-134PubMed Google Scholar, 2Cadenas E. Boveris A. Ragan C.I. Stoppani A.O. Arch. Biochem. Biophys. 1977; 180: 248-257Crossref PubMed Scopus (687) Google Scholar, 3Cadenas E. Boveris A. Biochem. J. 1980; 188: 31-37Crossref PubMed Scopus (235) Google Scholar, 4Turrens J.F. Boveris A. Biochem. J. 1980; 191: 421-427Crossref PubMed Scopus (1350) Google Scholar, 5Nohl H. Hegner D. Eur. J. Biochem. 1978; 82: 563-567Crossref PubMed Scopus (468) Google Scholar, 6Nohl H. Breuninger V. Hegner D. Eur. J. Biochem. 1978; 90: 385-390Crossref PubMed Scopus (144) Google Scholar, 7Cadenas E. Davies K.J. Free Radic. Biol. Med. 2000; 29: 222-230Crossref PubMed Scopus (2329) Google Scholar, 8Boveris A. Chance B. Biochem. J. 1973; 134: 707-716Crossref PubMed Scopus (2076) Google Scholar, 9Loschen G. Azzi A. Flohe L. FEBS Lett. 1973; 33: 84-87Crossref PubMed Scopus (157) Google Scholar, 10Boveris A. Cadenas E. FEBS Lett. 1975; 54: 311-314Crossref PubMed Scopus (329) Google Scholar). in the of KGDH and SDH under conditions the for NADH and is as the for of H2O2 to in of SDH and KGDH and the of of electron transport. potential for H2O2 the mitochondria are not inactivation of KGDH and SDH oxygen radical under conditions of and during normal In study, of H2O2 during conditions of inactivation of KGDH and SDH at the concentration of H2O2 the response of mitochondria to H2O2 under is that H2O2 and certain oxygen radicals cellular that H2O2 is of by H2O2 and oxygen radicals reversible of and in the molecules and G. J. Biol. PubMed Google Scholar, J. Biol. PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, J. Biol. PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, H. H. J. 17: PubMed Scopus Google Scholar, H. H. H. Biol. 2000; PubMed Scopus Google Scholar) Arch. Biochem. Biophys. 2000; PubMed Scopus Google Scholar, FEBS Lett. 2000; PubMed Scopus Google Scholar, A. Free Radic. Biol. Med. PubMed Scopus Google Scholar, H. H. PubMed Scopus Google Scholar, Med. PubMed Scopus Google Scholar). the role of H2O2 in mitochondria it is to the SDH and KGDH are and Inactivation of SDH and KGDH is not because of direct interaction with H2O2. In addition, removal of H2O2 is not sufficient for reactivation. These results that SDH and KGDH are to the of the are by activity are the potential role of the and the of SDH and KGDH to reversible is under the conditions of the to SDH and KGDH were of the concentration of H2O2 with the sensitivity of enzymes to a of reversible inactivation. The results of in to KGDH and H2O2 is to with in inactivation. The of aconitase to radical inactivation is in with A. J. Biol. PubMed Google Scholar, D. J. PubMed Google Scholar, J. Biochem. J. PubMed Scopus Google Scholar, J.F. J. Biol. PubMed Google Scholar, J. Biol. PubMed Google Scholar, J. Biol. PubMed Scopus Google Scholar, H. PubMed Scopus Google Scholar, A. 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Because of incomplete removal of the removal of for the reversible nature of inactivation In the present study, aconitase activity the rate of state 3 respiration is with α-ketoglutarate as a aconitase activity is not for the of that the of aconitase inactivation and to state 3 that result in the of the Krebs In the by mitochondria to a of mitochondrial in the of mitochondria to changes in and in a with In study, that mitochondrial respiration and the of mitochondrial enzymes are by the of H2O2 in a reversible suggest a role for radicals in regulation of mitochondrial direct of that to In addition, to the of and H2O2 a of of the and radical as as of mitochondrial respiration and KGDH activity in H. Biophys. PubMed Scopus Google J. PubMed Scopus Google Scholar, PubMed Scopus Google and G. G. J. Biol. PubMed Google Scholar, J. 82: PubMed Scopus Google Scholar, A. PubMed Scopus Google Scholar, A. PubMed Scopus Google Scholar, H. H. A. A. PubMed Scopus Google Scholar, H. A. G. J. PubMed Scopus Google Scholar). of the radical and mitochondrial to by radicals to the of