Hydrogen peroxide as the product of autoxidation of ferredoxin: Reduced either chemically or by illuminated chloroplasts

Telfer, Alison; Cammack, Richard; Evans, M.C.W.

doi:10.1016/0014-5793(70)80406-9

Cited by 39 publications

(21 citation statements)

References 10 publications

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“…Studies have shown that when soluble ferredoxin is added to isolated thyla koids in sufficient concentration (around 100 j.LM), oxygen can act as a terminal electron acceptor at a rate equal to or greater than NADP+ (2,43,121). ATP synthesis coupled to this electron transfer proceeds with ATP!2e ratios similar to that for NADP+ reduction (43,121).…”

Section: Atp Generation Linked To Photoreduction Of 02mentioning

confidence: 97%

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Photosynthetic Oxygen Exchange

Badger¹

1985

Annu. Rev. Plant. Physiol.

218

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Section: Atp Generation Linked To Photoreduction Of 02mentioning

confidence: 97%

“…It readily reacts in its reduced state in a one-electron transfer to O2 to form superoxide (93,98,103,121): '…”

Section: Photoreduction Of Oxygenmentioning

confidence: 99%

Photosynthetic Oxygen Exchange

Badger¹

1985

Annu. Rev. Plant. Physiol.

218

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“…Data supporting this view are presented in Tables VIII and IX (27) demonstrated that H202 is the result of an autooxidation of reduced ferredoxin.…”

Section: Communication)mentioning

confidence: 69%

Formation of Glycolate by a Reconstituted Spinach Chloroplast Preparation

Shain

Gibbs

1971

Plant Physiol.

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transketolase; 1 j,M U-'4C-fructose-6-P, specific radioactivity 0.4 mcj,'mmole; 20 ,ig of chlorophyll in a total volume of 0.33 ml.The assay was performed at 20 C in a controlled temperature bath equipped with incandescent lighting of 1200 ft-c. The reaction was stopped by adding 0.34 ml of boiling absolute ethyl alcohol, and the tubes were removed to an 80 C water bath for 3 min. The test tubes were then centrifuged at 10,000g for 10 min, and the glycolate present in the supernatant fraction was determined. The supernatant fluid was applied to a Dowex AG 1X8 acetate (100-200 mesh) column (6 X 50 cm), and glycolate was eluted according to the method of Zelitch (33). After application of the sample the column was washed with 15 ml of H20. Glycolate was eluted with 10 ml of 4 M acetic acid. Paper chromatography in a 1-butanol, propionic acid, water solvent (9.4:3:4 v, 'v) confirmed that the eluate contained only glycolate. In this procedure more than 99.9%O of the U-14C-fructose-6-P applied was retained in the column. The recovery of added glycolate-U-14C was better than 95%c A 3-ml aliquot of the acetic acid eluate was placed in 15 ml of a liquid scintillation mixture consisting of 100 g of naphthalene,

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“…Although noncyclic electron flow to oxygen is known to be coupled to ATP synthesis in ferredoxin-catalyzed pseudocyclic photophosphorylation (31), the role of supplying additional ATP for assimilatory reactions is equally well taken by cyclic photophosphorylation, and more recent evidence suggests that cyclic electron flow may be important in a variety of physiological circumstances (4,5). Far from eliminating need for photosynthetic reduction of oxygen, the operation of cyclic photophosphorylation is crucially dependent on maintenance of correct redox poise, and seems to require the availability of oxygen as an electron sink or "safety valve" to compensate for overreduction of the cyclic electron transfer chain, as proposed originally by Grant and Whatley (17).…”

Section: Allenmentioning

confidence: 99%

Superoxide as an Obligatory, Catalytic Intermediate in Photosynthetic Reduction of Oxygen by Adrenaline and Dopamine

Allen

2003

Antioxidants & Redox Signaling

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The superoxide anion radical is known to be the first product of photosynthetic reduction of oxygen mediated by a variety of electron carriers. The effectiveness of many of these electron carriers as herbicides, and the toxicity of the superoxide they produce, have been suggested to rule out oxygen reduction as a physiological component of normal photosynthesis. Here results with isolated spinach chloroplasts are presented that demonstrate that the related catecholamines adrenaline and dopamine mediate photosynthetic reduction of oxygen. Complete inhibition by added superoxide dismutase of light-dependent oxygen uptake by isolated chloroplasts and of the electron transport it supports indicates that superoxide is an obligatory catalytic intermediate, not a product, in adrenaline- and dopamine-mediated oxygen reduction. These compounds might function as chemical analogues of a proposed natural mediator, or oxygen-reducing factor, that allows oxygen reduction to participate in energy transduction in photosynthesis. The identity of the putative natural mediator and the role of oxygen reduction in photosynthesis are discussed. The fully oxidized form of adrenaline, adrenochrome, also acts as a mediator of photosynthetic oxygen uptake, but only by reducing oxygen to superoxide.

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Hydrogen peroxide as the product of autoxidation of ferredoxin: Reduced either chemically or by illuminated chloroplasts

Cited by 39 publications

References 10 publications

Photosynthetic Oxygen Exchange

Photosynthetic Oxygen Exchange

Formation of Glycolate by a Reconstituted Spinach Chloroplast Preparation

Superoxide as an Obligatory, Catalytic Intermediate in Photosynthetic Reduction of Oxygen by Adrenaline and Dopamine

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