The response of Azotobacter chroococcum to oxygen: superoxide-mediated effects

1977 ◽  
Vol 23 (11) ◽  
pp. 1548-1553 ◽  
Author(s):  
Alfred G. Buchanan
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Oxygen Uptake ◽  
Superoxide Anion ◽  
Azotobacter Chroococcum ◽  
Continuous Cultures ◽  
Whole Cells ◽  
Mediated Effects ◽  
Nitrogenase Inhibition

Nitrogenase in Azotobacter chroococcum whole cells was inhibited by enzymically generated superoxide anion (O2−), hydrogen peroxide, and ethyl hydrogen peroxide. The degree of inhibition produced by O2− was related to the quantity of oxygen supplied to the organisms in continuous cultures. O2− also inhibited oxygen uptake by whole cells. These O2−-mediated inhibitions were prevented by bovine superoxide dismutase. The quantities of superoxide dismutase (SOD), and catalase associated with cells grown under varying oxygen concentrations were determined. The role of hydrogen peroxide, and of the hydroxyl radical (∙OH) in nitrogenase inhibition was examined. The response of Azotobacter chroococcum to oxygen was evaluated with respect to the observed effects of O2− on the organism, and some explanation is given to account for nitrogenase sensitivity to oxygen.

Reactive forms of oxygen and chemiluminescence in phagocytizing rabbit alveolar macrophages

1978 ◽  
Vol 235 (3) ◽  
pp. C103-C108 ◽  
Author(s):  
P. R. Miles ◽  
V. Castranova ◽  
P. Lee
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Hydroxyl Radical ◽  
Alveolar Macrophages ◽  
Superoxide Anion ◽  
Extracellular Fluid ◽  
Particle Uptake ◽  
O2 Production

Chemiluminescence (CL), superoxide anion (O2-) production, and particle uptake were measured to determine the role of antibacterial substances in the chemiluminescent response associated with phagocytosis in rabbit alveolar macrophages (AM). Exposure of AM to zymosan particles induced both CL and the production of extracellular O2-. CL is inhibited by superoxide dismutase, an enzyme which catalyzes the conversion of O2- to hydrogen peroxide (H2O2), by catalase, an enzyme which destroys H2O2, and by the hydroxyl radical (.OH) scavengers, benzoate and ethanol. Superoxide dismutase and catalase probably exert their effects in the extracellular fluid. CL can also be produced by the addition of NaO2 or H2O2 to zymosan in a noncellular system. The chemiluminescent response occurs before particle uptake is complete, which also indicates that CL occurs in the extracellular fluid. These results suggest that CL induced by zymosan in AM is due to the extracellular reaction between various reactive forms of oxygen and zymosan.

Research of corrosion fracture of D16t and AMg6 aluminum alloys exposed to microscopic fungi

2021 ◽  
pp. 163-183
Author(s):  
D. V. Belov ◽  
S. N. Belyaev ◽  
M. V. Maksimov ◽  
G. A. Gevorgyan
Keyword(s):  
Hydrogen Peroxide ◽  
Aluminum Alloys ◽  
Superoxide Anion ◽  
Anion Radical ◽  
Corrosion Damage ◽  
Oxygen Species ◽  
Microscopic Fungi ◽  
Reductive Activation ◽  
Activation Of Oxygen

This paper presents an experimental study of biocorrosion of D16T and AMg6 aluminum alloys. The determining role of reactive oxygen species in aluminum biocorrosion by a consortium of molds has been shown. A model is proposed, according to which the initiators of corrosion damage to the metal surface are superoxide anion radical and hydrogen peroxide released during the life of micromycetes. It is assumed that the initiation and development of biocorrosion occurs, among other things, as a result of the process of reductive activation of oxygen and the Fenton decomposition of hydrogen peroxide. A conclusion is made about the mechanism of the occurrence of intergranular and pitting corrosion of aluminum alloys interacting with microscopic fungi.

scholarly journals Does superoxide anion participate in 2-oxoglutarate-dependent hydroxylation?

1982 ◽  
Vol 205 (2) ◽  
pp. 339-344 ◽  
Author(s):  
Elisabeth Holme ◽  
Göran Lindstedt ◽  
Sven Lindstedt ◽  
Ingalill Nordin
Keyword(s):  
Superoxide Dismutase ◽  
Superoxide Anion ◽  
Potent Inhibitor ◽  
Enzymic Activity ◽  
Heat Inactivation ◽  
Low Molecular Weight ◽  
Enzyme Protein ◽  
Erythrocyte Superoxide Dismutase ◽  
Rule Out

The possible role of superoxide anion in 2-oxoglutarate-coupled dioxygenase reactions has been investigated. γ-Butyrobetaine hydroxylase (EC 1.14.11.1) was inhibited by human erythrocyte superoxide dismutase (EC 1.15.1.1), probably due to release of Cu2+ or Zn2+, as the inhibition was more pronounced after heat-inactivation of the dismutase and as Cu2+ was a potent inhibitor. Bovine superoxide dismutase and the Mn2+-containing superoxide dismutase from Escherichia coli were not inhibitory. Superoxide anion generated from xanthine/xanthine oxidase was not stimulatory and could not replace ascorbate. Thymine 7-hydroxylase (EC 1.14.11.6) and thymidine 2′-hydroxylase (EC 1.14.11.3) were not inhibited by erythrocyte superoxide dismutase or stimulated by superoxide anion. γ-Butyrobetaine hydroxylase was inhibited by a number of low-molecular-weight compounds, such as tetranitromethane, Nitro Blue Tetrazolium, adrenaline and Tiron, which may act as scavengers of superoxide anion. Involvement of this radical in other oxygenase reactions has been inferred from the findings that they were inhibitory for the respective enzymes. Several of these compounds also inhibited γ-butyrobetaine hydroxylase. It could be concluded from these experiments, however, that mechanisms other than disposal of superoxide anion might equally well be operative, such as hydrophobic interaction with the enzyme protein and interaction with compounds required for full enzymic activity, e.g. iron and ascorbate. The results appear to rule out a requirement for superoxide anion generated in free solution, and have not yielded evidence for participation of enzyme-bound superoxide anion in 2-oxoglutarate-dependent hydroxylations.

scholarly journals Mitochondrial Superoxide Dismutase and Yap1p Act as a Signaling Module Contributing to Ethanol Tolerance of the Yeast Saccharomyces cerevisiae

2016 ◽  
Vol 83 (3) ◽  
Author(s):  
Anna N. Zyrina ◽  
Ekaterina A. Smirnova ◽  
Olga V. Markova ◽  
Fedor F. Severin ◽  
Dmitry A. Knorre
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Ethanol Tolerance ◽  
Yeast Cells ◽  
Ethanol Stress ◽  
Mitochondrial Enzymes ◽  
Mitochondrial Superoxide ◽  
Mitochondrial Superoxide Dismutase

ABSTRACT There are two superoxide dismutases in the yeast Saccharomyces cerevisiae—cytoplasmic and mitochondrial enzymes. Inactivation of the cytoplasmic enzyme, Sod1p, renders the cells sensitive to a variety of stresses, while inactivation of the mitochondrial isoform, Sod2p, typically has a weaker effect. One exception is ethanol-induced stress. Here we studied the role of Sod2p in ethanol tolerance of yeast. First, we found that repression of SOD2 prevents ethanol-induced relocalization of yeast hydrogen peroxide-sensing transcription factor Yap1p, one of the key stress resistance proteins. In agreement with this, the levels of Trx2p and Gsh1p, proteins encoded by Yap1 target genes, were decreased in the absence of Sod2p. Analysis of the ethanol sensitivities of the cells lacking Sod2p, Yap1p, or both indicated that the two proteins act in the same pathway. Moreover, preconditioning with hydrogen peroxide restored the ethanol resistance of yeast cells with repressed SOD2. Interestingly, we found that mitochondrion-to-nucleus signaling by Rtg proteins antagonizes Yap1p activation. Together, our data suggest that hydrogen peroxide produced by Sod2p activates Yap1p and thus plays a signaling role in ethanol tolerance. IMPORTANCE Baker's yeast harbors multiple systems that ensure tolerance to high concentrations of ethanol. Still, the role of mitochondria under severe ethanol stress in yeast is not completely clear. Our study revealed a signaling function of mitochondria which contributes significantly to the ethanol tolerance of yeast cells. We found that mitochondrial superoxide dismutase Sod2p and cytoplasmic hydrogen peroxide sensor Yap1p act together as a module of the mitochondrion-to-nucleus signaling pathway. We also report cross talk between this pathway and the conventional retrograde signaling cascade activated by dysfunctional mitochondria.

Haematoporphyrin enhances the peroxidase activity of haemoglobin

2000 ◽  
Vol 04 (02) ◽  
pp. 168-174 ◽  
Author(s):  
SUSMITA SIL ◽  
MANOJ KAR ◽  
ABHAY SANKAR CHAKRABORTI
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Conformational Change ◽  
Anticancer Drugs ◽  
Peroxidase Activity ◽  
Superoxide Anion ◽  
Spectrophotometric Study ◽  
Stoichiometric Ratio ◽  
Mediated Oxidation

The effect of haematoporphyrin, a component of some of the widely used anticancer drugs, on the peroxidase activity of haemoglobin has been studied. Haematoporphyrin increases the haemoglobin-catalysed hydrogen peroxide-mediated oxidation of o-dianisidine or NADH. Spectrophotometric study reveals that an interaction occurs between haemoglobin and haematoporphyrin which leads to a conformational change of the protein. The extent of enhanced peroxidase activity as well as conformational change of the protein vary in a positive manner with the stoichiometric ratio of haematoporphyrin/haemoglobin. An increase in the peroxidase activity of haemoglobin was also observed in the presence of superoxide dismutase, which catalysed the removal of superoxide anion generated during autoxidation of haemoglobin. Possible mechanisms underlying the relation between the conformational change of haemoglobin due to its interaction with haematoporphyrin and the enhanced peroxidase activity are discussed.

Superoxide dismutase activity in root-colonizing pseudomonads

1993 ◽  
Vol 39 (4) ◽  
pp. 420-429 ◽  
Author(s):  
J. Katsuwon ◽  
R. Zdor ◽  
A. J. Anderson
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Superoxide Anion ◽  
Plant Root ◽  
Polyacrylamide Gel Electrophoresis ◽  
Root Surface ◽  
Superoxide Anion Production ◽  
E Coli ◽  
Phosphate Availability ◽  
External Sources

Several saprophytic fluorescent pseudomonads that are aggressive root colonizers express similar specific activities of superoxide dismutase during growth in liquid culture. The pseudomonads have the potential to produce hydrogen peroxide sensitive and hydrogen peroxide insensitive isoforms of superoxide dismutase with distinct mobilities in nondenaturing polyacrylamide gel electrophoresis. Synthesis of the hydrogen peroxide insensitive form is enhanced by limited iron availability, by exposure to Mn2+, and to a lesser extent by external sources of superoxide anion. Unlike Pseudomonas aeruginosa, a root-colonizing strain of Pseudomonas putida did not show regulation of isoform pattern by phosphate availability. A plasmid potentially encoding the pseudomonad hydrogen peroxide sensitive form complemented the superoxide dismutase deficiency in a mutant of Escherichia coli lacking expression of both Fe and Mn genes. Contact between the plant root and pseudomonad or E. coli cells that lack or express superoxide dismutase did not influence superoxide anion production from root surface enzymes. The pseudomonad and the superoxide dismutase deficient and producing E. coli strains survived exposure to the root equally well. Only the hydrogen peroxide sensitive isoform of superoxide dismutase was detected in P. putida cells associated with bean root surfaces.Key words: pseudomonads, activated oxygen, root surface colonization.

scholarly journals The Antioxidant Machinery of Young and Senescent Human Umbilical Vein Endothelial Cells and Their Microvesicles

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Guillermo Bodega ◽  
Matilde Alique ◽  
Lourdes Bohórquez ◽  
Sergio Ciordia ◽  
María C. Mena ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Endothelial Cells ◽  
Superoxide Anion ◽  
Umbilical Vein ◽  
Redox Status ◽  
Human Umbilical Vein ◽  
Umbilical Vein Endothelial Cells ◽  
Ros Scavengers ◽  
Antioxidant Machinery

We examine the antioxidant role of young and senescent human umbilical vein endothelial cells (HUVECs) and their microvesicles (MVs). Proteomic and Western blot studies have shown young HUVECs to have a complete and well-developed antioxidant system. Their MVs also contain antioxidant molecules, though of a smaller and more specific range, specialized in the degradation of hydrogen peroxide and the superoxide anion via the thioredoxin-peroxiredoxin system. Senescence was shown to be associated with a large increase in the size of the antioxidant machinery in both HUVECs and their MVs. These responses might help HUVECs and their MVs deal with the more oxidising conditions found in older cells. Functional analysis confirmed the antioxidant machinery of the MVs to be active and to increase in size with senescence. No glutathione or nonpeptide antioxidant (ascorbic acid and vitamin E) activity was detected in the MVs. Endothelial cells and MVs seem to adapt to higher ROS concentrations in senescence by increasing their antioxidant machinery, although this is not enough to recover completely from the senescence-induced ROS increase. Moreover, MVs could be involved in the regulation of the blood plasma redox status by functioning as ROS scavengers.

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