Inhibitors of superoxide dismutases: A cautionary tale

Hassan, Hosni M.; Dougherty, Harry W.; Fridovich, Irwin

doi:10.1016/0003-9861(80)90290-8

Cited by 30 publications

(7 citation statements)

References 12 publications

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“…However, superoxide dismutase can inhibit reaction (3) in the presence of 02 by removing 02-and displacing equilibrium (1) to the left. This would either prevent the formation of the alloxan radical or accelerate its removal, thus inhibiting its reaction with cytochrome c. This mechanism is similar to that proposed to account for the apparent inhibition of superoxide dismutase by pamoic acid (Hassan et al, 1980), and could also explain some of the findings obtained by Crouch et al (1981) with alloxan and other diabetogenic drugs. It requires that reaction (1) is reversible, which is in accordance with the proposal of Houee et al (1981), and with the behaviour of other quinones (Winterbourn, 1981;Sutton & Sangster, 1982).…”

supporting

confidence: 60%

Superoxide dismutase-inhibitible reduction of cytochrome c by the alloxan radical. Implications for alloxan cytotoxicity

Winterbourn¹

1982

Biochemical Journal

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Cytochrome c was reduced when superoxide was generated from xanthine oxidase in the presence of alloxan, and by the reaction of alloxan and with reduced glutathione. In each case, most of the reduction was inhibited by superoxide dismutase, but considerably more enzyme was required than with superoxide alone. This indicates that the superoxide dismutase-inhibitible cytochrome c reduction was mainly due to a direct reaction with the alloxan radical, and implies that other reactions that are inhibited by superoxide dismutase could be due to either alloxan radicals or superoxide.

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confidence: 60%

Superoxide dismutase-inhibitible reduction of cytochrome c by the alloxan radical. Implications for alloxan cytotoxicity

Winterbourn¹

1982

Biochemical Journal

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“…Obviously, anything that inhibits xanthine oxidase will decrease the rate of reduction of the cytochrome and thus appear to have SOD activity. Likewise, any compound that competes with the cytochrome c for O 2 · – will result in an apparent decrease in [SOD] or look like an inhibitor of SOD [ 23 ]. A control is needed to establish that the material being tested does not directly inhibit xanthine oxidase.…”

Section: Assays For Sod Activitymentioning

confidence: 99%

Oxygen: How Do We Stand It?

Fridovich

2012

Med Princ Pract

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The electronic structure of ground state oxygen, which is essential for the life of all aerobic organisms, makes it potentially dangerous for those organisms. Atmospheric oxygen contains two unpaired electrons with parallel spin states, which predisposes it to reduction by a univalent pathway. As a consequence, normal aerobic metabolism generates dangerous reactive intermediates of the reduction of O 2 . These include superoxide radical (O 2 – ), hydrogen peroxide (H 2 O 2 ), and hydroxyl radical (HO). These reactive oxygen species and others that they can engender can damage all cellular macromolecules and unless opposed by cellular defenses, would make aerobic life impossible. Such defenses include superoxide dismutases, catalases, and peroxidases, enzymes that decrease the concentration of the reactive oxygen species that are their substrates, and others that repair or recycle oxidatively damaged macromolecules. Any factor that stimulates reactive oxygen species production or suppresses the antioxidant systems would inevitably cause cell damage. The role of such oxidative damage in various diseases is well documented. In vivo detection of O 2– and other reactive oxygen species is however hampered by the lack of easy, specific, and sensitive analytical methods. Potential artifacts and limitations of the most common detection methods currently in use are briefly discussed.

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“…Studies with E. coli have suggested that a repressor protein containing Fez+ may be related to the control of Mn-SOD synthesis. When Fe2+ is removed from the repressor, or oxidation of Fez+ to Fe3+ occurs in the presence of oxygen, the repressor is inactivated and the Mn-SOD gene is transcribed (Hassan et at. 1980).…”

Section: -mentioning

confidence: 99%

EFFECTS OF CADMIUM ON GROWTH AND SUPEROXIDE DISMUTASE ACTIVITY OF THE MARINE MICROALGA TETRASELMIS GRACILIS (PRASINOPHYCEAE)¹

Okamoto

Asano

Aidar

et al. 1996

Journal of Phycology

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Marine planktonic algae are frequently exposed to metallic contaminants. Because heavy metals can be assimilated and accumulated by algal cells, they can then be transferred to higher trophic levels of food chains. We studied the effects of cadmium on protein production and the growth of the marine prasinophyte Tetraselmis gracilis (Kylin) Butcher. By means of toxicological assays, we estimated the LC50 of cadmium as 3.2 ppm and 1.8 ppm after 48 h and 96 h of exposure to this heavy metal, respectively. The growth curves and survival percentages of cell cultures in the presence of cadmium were determined, and a proportional reduction of both parameters with increasing metal concentrations was found. When chronically exposed to sublethal concentrations of cadmium, T. gracilis contained high levels of superoxide dismutase (SOD) activity, one of the main enzymes of the cell's antioxidant defense mechanism. Under these growth conditions, total SOD activity in crude extracts was increased by 41% (at 1.5 ppm) and 107% (at 3.0 ppm). Assays of SOD activity in nondenaturing polyacrylamide gels also showed a similar induction by cadmium. These results show that cadmium has potentially toxic properties since it significantly inhibited the growth of T. gracilis at low concentrations and promoted the induction of SOD activity, suggestive of an oxidative stress state. Besides being the first report of SOD in T. gracilis, this work describes experimental evidence of SOD induction by cadmium in this species.

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Inhibitors of superoxide dismutases: A cautionary tale

Cited by 30 publications

References 12 publications

Superoxide dismutase-inhibitible reduction of cytochrome c by the alloxan radical. Implications for alloxan cytotoxicity

Superoxide dismutase-inhibitible reduction of cytochrome c by the alloxan radical. Implications for alloxan cytotoxicity

Oxygen: How Do We Stand It?

EFFECTS OF CADMIUM ON GROWTH AND SUPEROXIDE DISMUTASE ACTIVITY OF THE MARINE MICROALGA TETRASELMIS GRACILIS (PRASINOPHYCEAE)¹

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Inhibitors of superoxide dismutases: A cautionary tale

Cited by 30 publications

References 12 publications

Superoxide dismutase-inhibitible reduction of cytochrome c by the alloxan radical. Implications for alloxan cytotoxicity

Superoxide dismutase-inhibitible reduction of cytochrome c by the alloxan radical. Implications for alloxan cytotoxicity

Oxygen: How Do We Stand It?

EFFECTS OF CADMIUM ON GROWTH AND SUPEROXIDE DISMUTASE ACTIVITY OF THE MARINE MICROALGA TETRASELMIS GRACILIS (PRASINOPHYCEAE)1

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EFFECTS OF CADMIUM ON GROWTH AND SUPEROXIDE DISMUTASE ACTIVITY OF THE MARINE MICROALGA TETRASELMIS GRACILIS (PRASINOPHYCEAE)¹