Deactivation of superoxide dismutase on EDTA‐treated chloroplasts

Schmid, Roland

doi:10.1016/0014-5793(75)80427-3

Cited by 6 publications

(4 citation statements)

References 18 publications

(20 reference statements)

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“…In contrast, the SOD found in most organisms eliminate 02 in a way analogous to the action of catalase on H202. The ability of Mn(II) to scavenge 02 has previously been noted (26,27,35) and may at least partially explain the reports (10,11) that Mn(II) inhibits lipid peroxidation in biological membranes. Plant material is rich in Mn, and the natural association of L. plantarum with fermenting plant material would allow it ready access to that metal in nature.…”

Section: Discussionmentioning

confidence: 79%

“…For over 30 years the lactobacilli have been known to require large amounts of Mn for growth (28). More recently, Mn(II) has been shown to be effective in scavenging 02 (5,25,27,35), except in the presence of EDTA (27,35,36). Since xanthine oxidase is susceptible to an activity-dependent inactivation by trace metals (12), 0.1 mM EDTA is routinely included in the SOD assay; in the presence of EDTA, no 02-scavenging activity could be detected in L. plantarum.…”

Section: Resultsmentioning

confidence: 99%

“…Plant material is rich in Mn, and the natural association of L. plantarum with fermenting plant material would allow it ready access to that metal in nature. Chloroplasts contain plentiful Mn, both free and bound, and the oxidation of Mn(ll) by illuminated chloroplasts due to O2 has been noted by many workers (25)(26)(27)35). Indeed, Kono et al (26) reported the rate constant for the oxidation of Mn(II)-pyrophosphate by O2 to be 6 x 106 M-1 s-1 and suggested that one function of the free Mn(II), within chloroplasts, might be the scavenging of 02-.…”

Section: Discussionmentioning

confidence: 96%

“…Mn(II) is known to be oxidized by O2 (5,25,26,35). In the presence of pyrophosphate the product is a stable Mn(III)-pyrophosphate (26), and in the absence of stabilizing chelators the product is believed to be MnO2+(5).…”

Section: Discussionmentioning

confidence: 99%

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Manganese and Defenses against Oxygen Toxicity in Lactobacillus plantarum

1981

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Lactobacillus plantarum is aerotolerant during log-phase growth on glucose, but is an obligate aerobe on polyols. Respiration was cyanide resistant and under certain conditions was associated with the accumulation of millimolar concentrations of H202. On glucose, optimal growth was observed in the absence of 02. Extracts of L. plantarum did not catalyze the reduction of paraquat by reduced nicotinamide adenine dinucleotide, but plumbagin (5-hydroxy-2-methyl-1,4naphthoquinone) was readily reduced. Such extracts produced O2 in the presence of NADH plus plumbagin. Plumbagin caused a 10-fold increase in the rate of respiration of intact cells in the presence of glucose and also imposed a loss of viability which was dependent upon both glucose and 02. Although extracts of L. plantarum were devoid of true superoxide dismutase activity, this organisim was comparable to superoxide dismutase-containing species in its resistance toward hyperbaric 02 and toward the oxygen-dependent lethality of plumbagin. L. plantarum required Mn-rich media and actively accumulated Mn(II). Soluble extracts were found to contain approximately 9 jig of Mn per mg of protein and 75 to 90% of this Mn was dialyzable. Such extracts exhibited a dialyzable and ethylenediaminetetraacetic acid-inhibitable ability to scavenge 02. This 02scavenging activity was due to the dialyzable Mn(ll) present in these extracts and could be mimicked by MnCl2. Cells grown in Mn-rich media were enriched in dialyzable Mn and were more resistant toward oxygen toxicity and toward the oxygen-dependent plumbagin toxicity than were cells grown in Mn-deficient media. L. plantarum exhibited no nutritional requirement for iron and little or no iron was present in these cells, even when they were grown in iron-rich media. L.

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Section: Discussionmentioning

confidence: 79%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

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Manganese and Defenses against Oxygen Toxicity in Lactobacillus plantarum

1981

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Superoxide Radical and Superoxide Dismutases

Fridovich¹

1981

Topics in Environmental Physiology and Medicine

331

337

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The metalloenzymes that have been named superoxide dismutases have several attributes. They are abundant, widely distributed, essential as a defense against oxygen toxicity; they are also unique among enzymes in that their natural substrate is an unstable free radical. They are evolution's answer to the biological production of the superoxide radical (0 2 ), This free radical, previously considered only in connection with the high energy irradiation of oxygenated aqueous media, is also produced under ordinary circumstances within respiring cells. The superoxide radical is intrinsically reactive and can furthermore engender other enormously reactive radicals and excited states which are potentially capable of destroying the delicate chemical architecture of the cell. The intermediates of oxygen reduction, i.e., O 2 , H 2 0 2 , and OH', are the primary cause of oxygen toxicity; the enzymes, which catalytically scavenge them or prevent their production, are the foremost defenses which limit that toxicity. H2~ and the catalases anc! peroxidases, which scavenge it, are discussed in other chapters of this volume. We shall devote ourselves to superoxide and the superoxide dismutases.

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