Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.3.5.1 (succinate dehydrogenase)
8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Three nuclear mutants of Saccharomyces cerevisiae deficient in succinate dehydrogenase have been isolated. Two of these mutants are allelic. 2. The amount of covalently bound flavin of submitochondrial particles of the two allelic mutants is about 14% and that of the third mutant about 50% of the amount in wild-type particles. The turnover number of succinate dehydrogenase of particles is decreased in all mutants. The turnover number of fumarate reductase is increased in the two allelic mutants, but decreased in the third mutant. 3. EPR spectra, measured at 82 degrees K, show that the amplitude of the g equals 1.93 signal in particles of the two allelic mutants is less than 10% of that in wild-type particles. It is concluded that iron-sulphur centres other than those of succinate dehydrogenase make only a negligible contribution to the line at g equals 1.93 in wild-type particles. 4. EPR measurements below 20 degrees K show that the amplitude of the signal at g equals 2.01 detected in oxidized particles is decreased in particles of the two allelic mutants. 5. A signal with lines at g equals 2.027 and g equals 1.933 is detected at low temperatures in all particle preparations, even in those from a cytoplasmic petite mutant. It is suggested that this signal is derived from a contaminant and not from the inner membrane.
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PMID:EPR studies on the respiratory chain of wild-type Saccharomyces cerevisiae and mutants with a deficiency in succinate dehydrogenase. 16 68

Two distinct ferredosin-type iron-sulfur centers (designated as Centers S-1 and S-2) are present in the soulble succinate dehydrogenase in approximately equivalent concentrations to that of bound flavin. Both Centers S-1 and S-2 exhibit electron paramagnetic resonance absorbance in the reduced state at the same magnetic field (gz = 2.03, gy = 1.93, and gx = 1.91) with similar line shape. Center S-2 is reducible only chemically with dithionite and remains oxidized under physiological conditions. Thus, its functional role is unknown; however, thermodynamic and EPR characterization of this iron-sulfur center has revealed important molecular events related to this dehydrogenase. The midpoint potentials of Centers S-1 and S-2 determined in the soluble succinate dehydrogenase preparations are -5 +/- 15 mV and -400 +/- 15 mV, respectively, while corresponding midpoint potentials determined in particulate preparations, such as succinate-cytochrome c reductase or succinate-ubiquinone reductase, are 0 +/- 15 mV and -260 +/- 15 mV. Reconstitution of soluble succinate dehydrogenase with the cytochrome b-c1 complex is accompanied by a reversion of the Center S-I midpoint from -400 +/- 15 mV to -250 +/- 15 mV with a concomitant restoration of antimycin A-sensitive succinate-cytochrome c reductase activity. There observations indicate that, during the reconstitution process, Center S-I is restored to its original molecular environment. In the reconstitutively active succinate dehydrogenase, the relaxation time of Center S-2 is much shorter than that of S-1, thus Center S-2 spectra are well discernible only below 20 K (at 1 milliwatt of power), while the resonance absorbance of Center S-1 is detectable at higher temperatures and readily saturates below 15 K. Over a wide temperature range the power saturation of Center S-1 resonance absorbance is relieved by Center S-2 in the paramagnetic state, and the Center S-2 central resonance absorbance is broadened by Center S-1 spins, due to a spin-spin interaction between these centers. These observations indicate an adjacent location of these centers in the enzyme molecule. In reconstitutively inactive enzymes, subtle modification of the enzyme structure appears to shift the temperature dependence of Center S-2 relaxation to the higher temperature. Thus the EPR signals of Center S-2 are also detectable at higher temperature. In this system a splitting of the central peak of the Center S-2 spectrum due to spin-spin interaction was observed at extremely low temperatures, while this was not observed in reconstitutively active enzymes or in paritculate preparations. This spin-spin interaction phenomena of inactive enzymes disappeared upon chemical reactivation with concomitant appearance of the reconstitutive activity. These observations provide a close correlation between the molecular integrity of the enzyme and its physiological function.
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PMID:Thermodynamic and EPR characteristics of two ferredoxin-type iron-sulfur centers in the succinate-ubiquinone reductase segment of the respiratory chain. 17 55

In addition to the two species of ferredoxin-type iron-sulfur centers (Centers S-1 and S-2), a third iron-sulfur center (Center S-3), which is paramagnetic in the oxidezed state analogous to the bacterial high potential iron-sulfur protein, has bwen detected in the reconstitutively active soluble succinate dehydrogenase preparation. Midpoint potential (at pH 7.4) of Center S-3 determined in a particulate succinate-cytochrome c reductase is +60 +/- 15 mV. In soluble form, Center S-3 becomes extremely labile towards oxygen or ferricyanide plus phenazine methosulfate similar to reconstitutive activity of the dehydrogenase. Thus, even freshly prepared reconstitutively active enzyme preparations show EPR spectra of Center S-3 which correspond approximately to 0.5 eq per flavin; in particulate preparations this component was found in a 1:1 ratio to flavin. All reconstitutively inactive dehydrogenase preparations that Center S-3 is an innate constituent of succinate dehydrogenase and plays an important role in mediating electrons from the flavoprotein subunit to most probably ubiquinone and then to the cytochrome chain.
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PMID:Thermodynamic and EPR characteristics of a HiPIP-type iron-sulfur center in the succinate dehydrogenase of the respiratory chain. 17 56

The coupling constants J between the iron atoms in ferredoxin type iron-sulfur proteins containing binuclear clusters were evaluated by two parallel methods. The temperature dependence of the EPR linewidths and integrated abosrption intensities are both related to the energy of the first excited state. The values of J obtained were: center S-1 in succinate dehydrogenase, 90 cm-1; Rieske's iron-sulfur center, 65 cm-1; adrenodoxin, 270 cm-1. The behavior of iron-sulfur center N-1a in NADH:UQ reductase was also examined; its similarity to that of center S-1 indicates that center N-1a is also a binuclear iron-sulfur center, with J = 90 cm-1. Greater rhombic distortion present in the EPR spectrum of a binuclear cluster was associated with smaller values of J.
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PMID:Determination of the exchange integral in binuclear iron-sulfur clusters in proteins of varying complexity. 19 6

1. From the 57Fe hyperfine interaction in EPR spectra of reduced submitochondrial particles from the yeast Candida utilis, grown with 57Fe, it is concluded that all Fe-S centers in these particles detectable in spectra at 35-80 K are [2Fe-2S]2-(2-; 3-) centers. These are the centers 1 of NADH and succinate dehydrogenase, the Rieske Fe-S center and possibly center 2 of succinate dehydrogenase. 2. The signals of the reduced particles detectable only at temperatures below 20 K are [4Fe-4S]2-(2-; 3-) clusters. These are the centers 2,3 and 4 of NADH dehydrogenase. 3. EPR spectra of the [2Fe-2S]3- centers of Complex I and II, but not that of Complex III, display a great inequality of the Fe nuclei in the effective hyperfine interaction in the x-y direction.
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PMID:The number of Fe atoms in the iron-sulphur centers of the respiratory chain. 19 54

An EPR investigation of the region of the higher plant respiratory chain involving ubiquinone and Center S-3 of succinate dehydrogenase is reported. At temperatures close to those of liquid helium, first derivative spectra corresponding to Center S-3 (gmax = 2.017) and a signal split around g = 2.00 (major features of peaks and troughs at g values of 2.045, 2.03, 1.985, 1.97 and 1.96) were observed in mung bean (Phaseolus aureus), Arum maculatum spadix, Sauromatum guttatum spadix and tulip bulb (Tulipa gesnerana) mitochondria. The split signal was small or absent in potato tuber and Symplocarpus foetidus spadix mitochondria. The redox behavior of these signals in mung bean mitochondria in a variety of respiratory steady-state conditions suggested that the components giving rise to them were an integral part of the respiratory chain and were located on the substrate side of coupling Site II. The split signal could be removed by addition of hydroxamic acids in all tissues tested, although the Ks of this effect was an order of magnitude higher than the Ki of inhibition of the alternative respiratory pathway in mung bean and Sauromatum guttatum spadix mitochondria. The results are discussed in relation to the current ideas on the ordering of components in the region around the classical Site II of the respiratory chain and in relation to the location of the alternative respiratory oxidase pathway of higher plants.
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PMID:EPR studies of higher plant mitochondria. I Ubisemiquinone and its relation to alternative respiratory oxidations. 20 4

A soluble enzymically active cytochrome b.c1 complex has been purified from baker's yeast mitochondria by a procedure involving solubilization in cholate, differential fractionation with ammonium sulfate, and ultracentrifugation. The resulting particle is free of both cytochrome c oxidase and succinate dehydrogenase activities. The complex contains cytochromes b and c1 in a ratio of 2:1 and quinone and iron-sulfur protein in amounts roughly stoichiometric with cytochrome c1. EPR spectroscopy has shown the iron-sulfur protein to be present mainly as the Rieske protein. EPR spectroscopy also shows a heterogeneity in the cytochrome b population with resonances appearing at g = 3.60 (cytochrome bK) and g = 3.76 (cytochrome bT). A third EPR resonance appearing in the region associated with low spin ferric hemes (g = 3.49) is assigned to cytochrome c1. Anaerobic titration of the complex with dithionite confirmed the heterogeneity in the cytochrome b population and demonstrated that the oxidation-reduction potential of the iron-sulfur protein is approximately 30 mV more positive than cytochrome c1. An intense EPR signal assigned to the coenzyme Q free radical appeared midway in the reductive titration; this signal disappeared toward the end of the titration. A conformational change in the iron-sulfur protein attendant on reduction of a low potential species was noted.
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PMID:The preparation and characterization of highly purified, enzymically active complex III from baker's yeast. 20 48

Oxidation factor, a protein required for electron transfer from succinate to cytochrome c in the mitochondrial respiratory chain, has been purified from isolated succinate . cytochrome c reductase complex. Purification of the protein has been followed by a reconstitution assay in which restoration of ubiquinol . cytochrome c reductase activity is proportional to the amount of oxidation factor added back to depleted reductase complex. The purified protein is a homogeneous polypeptide on acrylamide gel electrophoresis in sodium dodecyl sulfate and migrates with an apparent Mr = 24,500. Purified oxidation factor restores succinate . cytochrome c reductase and ubiquinol . cytochrome c reductase activities to depleted reductase complex. It is not required for succinate dehydrogenase nor for succinate . ubiquinone reductase activities of the reconstituted reductase complex. Oxidation factor co-electrophoreses with the iron-sulfur protein polypeptide of ubiquinol . cytochrome c reductase complex. The purified protein contains 56 nmol of nonheme iron and 36 nmol of acid-labile sulfide/mg of protein and possesses an EPR spectrum with the characteristic "g = 1.90" signal identical to that of the iron-sulfur protein of the cytochrome b . c1 complex. In addition, the optimal conditions for extraction of oxidation factor, including reduction with hydrosulfite and treatment of the b . c1 complex with antimycin, are identical to those which facilitate extraction of the iron-sulfur protein from the b . c1 complex. These results indicate that oxidation factor is a reconstitutively active form of the iron-sulfur protein of the cytochrome b . c1 complex first discovered by Rieske and co-workers (Rieske, J.S., Maclennan, D.H., and Coleman, R. (1964) Biochem. Biophys. Res. Commun. 15, 338-344) and thus demonstrate that this iron-sulfur protein is required for electron transfer from ubiquinol to cytochrome c in the mitochondrial respiratory chain.
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PMID:Purification of a reconstitutively active iron-sulfur protein (oxidation factor) from succinate . cytochrome c reductase complex of bovine heart mitochondria. 22 62

Site-directed mutants of Escherichia coli fumarate reductase in which FrdB Cys204, Cys210, and Cys214 were individually replaced by Ser and in which Val207 was replaced by Cys were constructed and overexpressed in a strain of E. coli lacking a wild-type copy of fumarate reductase and succinate dehydrogenase. The consequences of these mutations on bacterial growth, enzymatic activity, and the EPR properties of the constituent iron-sulfur clusters were investigated. The FrdB Cys204Ser, Cys210Ser, and Cys214Ser mutations result in enzymes with negligible activity that have dissociated from the membrane and consequently are incapable of supporting cell growth under conditions requiring a functional fumarate reductase. EPR studies indicate that these effects are associated with loss of both the [3Fe-4S] and [4Fe-4S] clusters, centers 3 and 2, respectively. In contrast, the FrdB Val207Cys mutation results in a functional membrane-bound enzyme that is able to support growth under anaerobic and aerobic conditions. However, EPR studies indicate that the indigenous [3Fe-4S]+,0 cluster (Em = -70 mV), center 3, has been replaced by a much lower potential [4Fe-4S]2+,+ cluster (Em = -350 mV), indicating that the primary sequence of the polypeptide determines the type of clusters assembled. The results of these studies afford new insights into the role of centers 2 and 3 in mediating electron transfer from menaquinol, the residues that ligate these clusters, and the intercluster magnetic interactions in the wild-type enzyme.
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PMID:[3Fe-4S] to [4Fe-4S] cluster conversion in Escherichia coli fumarate reductase by site-directed mutagenesis. 131 45

Succinate:menaquinone-7 oxidoreductase (complex II) of the Gram-positive bacterium Bacillus subtilis consists of equimolar amounts of three polypeptides; a 65-kDa FAD-containing polypeptide, a 28-kDa iron-sulfur cluster containing polypeptide, and a 23-kDa membrane-spanning cytochrome b558 polypeptide. The enzyme complex was overproduced 2-3-fold in membranes of B. subtilis cells containing the sdhCAB operon on a low copy number plasmid and was purified in the presence of detergent. The cytochrome b558 subunit alone was similarly overexpressed in a complex II deficient mutant and partially purified. Isolated complex II catalyzed the reduction of various quinones and also quinol oxidation. Both activities were efficiently albeit not completely blocked by 2-n-heptyl-4-hydroxyquinoline N-oxide. Chemical analysis demonstrated two protoheme IX per complex II. One heme component was found to have an Em,7.4 of +65 mV and an EPR gmax signal at 3.68, to be fully reducible by succinate, and showed a symmetrical alpha-band absorption peak at 555 nm at 77 K. The other heme component was found to have an Em,7.4 of -95 mV and an EPR gmax signal at 3.42, was not reducible by succinate under steady-state conditions, and showed in the reduced state an apparent split alpha-band absorption peak with maxima at 553 and 558 nm at 77 K. Potentiometric titrations of partially purified cytochrome b558 subunit demonstrated that the isolated cytochrome b558 also contains two hemes. Some of the properties, i.e., the alpha-band light absorption peak at 77 K, the line shapes of the EPR gmax signals, and reactivity with carbon monoxide were observed to be different in B. subtilis cytochrome b558 isolated and in complex II. This suggests that the bound flavoprotein and iron-sulfur protein subunits protect or affect the heme environment in the assembled complex.
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PMID:Two hemes in Bacillus subtilis succinate:menaquinone oxidoreductase (complex II). 132 13


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