Related Experiment Video
Updated: May 5, 2026

Simultaneous Measurement of Superoxide/Hydrogen Peroxide and NADH Production by Flavin-containing Mitochondrial Dehydrogenases
Published on: February 24, 2018
Heat-stress stimulation of oxygen uptake by Photosystem I involves the reduction of superoxide radicals by specific
1Centre de Recherche en Photobiophysique, Université du Québec à Trois-Rivières, C.P. 500, G9A 5H7, Trois-Rivières, Québec, Canada.
Abstract:
A Photosystem I submembrane fraction isolated from spinach was used to study the mechanism of heat-stress stimulation of oxygen uptake by the photosystem. Various artificial electron donors were shown to generate electron transport reactions with various degrees of thermally induced stimulation. A strong stimulation was observed with durohydroquinone as electron donor with a maximal effect at 50 °C. The degree of stimulation obtained was independent from the redox potential of the electron donors and from their oxidation site because the enzyme superoxide dismutase fully inhibited the stimulation. Instead, it is proposed that thermal stress causes the release of membrane bound superoxide dismutase from the thylakoids thus allowing the reduced form of electron donors with specific properties to reduce O2 (-) radicals to H2O2 besides the usual disproportionation of O2 (-) into O2 and H2O2.
More Related Videos
10:05Stimulation of Stem Cell Niches and Tissue Regeneration in Mouse Skin by Switchable Protoporphyrin IX-Dependent Photogeneration of Reactive Oxygen Species In Situ
Published on: May 8, 2020
10:46Evaluation of Photosynthetic Efficiency in Photorespiratory Mutants by Chlorophyll Fluorescence Analysis
Published on: December 9, 2022
Related Concept Videos
Oxygenic Photosynthesis
Electron Transport Chain: Complex III and IV
The Z-Scheme of Electron Transport in Photosynthesis
Photosystem II
The pigment molecules are arranged across two photosystem domains — the antenna complex and the reaction center. The main aim of the pigment...
Anoxygenic Photosynthesis
Photosystem I
Both these photosystems work in concert. An excited electron from PSII is relayed to PSI via an electron transport chain in the thylakoid membrane of the chloroplast, which is comprised of the carrier molecule plastoquinone, the dual-protein cytochrome complex, and plastocyanin. As electrons move between PSII and PSI, they lose energy and must be re-energized...