title: The resistance of electron-transport chain Fe-S clusters to oxidative damage during the reaction of peroxynitrite with mitochondrial complex II and rat-heart pericardium.
abstract: The effects of peroxynitrite and nitric oxide on the iron-sulfur clusters in complex II (succinate dehydrogenase) isolated from bovine heart have been studied primarily by EPR spectroscopy and no measurable damage to the constitutive 2Fe-2S, 3Fe-4S, or 4Fe-4S clusters was observed. The enzyme can be repeatedly oxidized with a slight excess of peroxynitrite and then quantitatively re-reduced with succinate. When added in large excess, peroxynitrite reacted with at least one tyrosine in each subunit of complex II to form 3-nitrotyrosines, but activity was barely compromised. Examination of rat-heart pericardium subjected to conditions leading to peroxynitrite production showed a small inhibition of complex II (16%) and a greater inhibition of aconitase (77%). In addition, experiments performed with excesses of sodium citrate and sodium succinate on rat-heart pericardium indicated that the "g approximately 2.01" EPR signal observed immediately following the beginning of conditions modeling oxidative/nitrosative stress, could be a consequence of both reversible oxidation of the constitutive 3Fe-4S cluster in complex II and degradation of the 4Fe-4S cluster in aconitase. However, the net signal envelope, which becomes apparent in less than 1min following the start of oxidative/nitrosative conditions, is dominated by the component arising from complex II. Taking into account the findings of a previous study concerning complexes I and III (L.L. Pearce, A.J. Kanai, M.W. Epperly, J. Peterson, Nitrosative stress results in irreversible inhibition of purified mitochondrial complexes I and III without modification of cofactors, Nitric Oxide 13 (2005) 254-263) it is now apparent that, with the exception of the cofactor in aconitase, mammalian (mitochondrial) iron-sulfur clusters are surprisingly resistant to degradation stemming from oxidative/nitrosative stress.
authors.affiliation: Department of Environmental and Occupational Health, University of Pittsburgh, 130 DeSoto St., Pittsburgh, PA 15261, USA. lip10@pitt.edu
authors.forename: Linda L
authors.initials: LL
authors.lastname: Pearce
authors.forename: Sandra
authors.initials: S
authors.lastname: Martinez-Bosch
authors.forename: Elisenda Lopez
authors.initials: EL
authors.lastname: Manzano
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Winnica
authors.forename: Michael W
authors.initials: MW
authors.lastname: Epperly
authors.forename: Jim
authors.initials: J
authors.lastname: Peterson
mesh_terms: D000818:Animals; D004578:Electron Spin Resonance Spectroscopy; D042963:Electron Transport Complex II / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010496:Pericardium / Q000378:metabolism*; D030421:Peroxynitrous Acid / Q000378:metabolism*; D051381:Rats; D013385:Succinate Dehydrogenase / Q000378:metabolism*
chemical_list: D007506:Iron-Sulfur Proteins; D024101:Mitochondrial Proteins; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase