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Oxygen evolution is the chemical process of generating elemental diatomic oxygen (O 2) by a chemical reaction, usually from water, the most abundant oxide compound in the universe. Oxygen evolution on Earth is effected by biotic oxygenic photosynthesis , photodissociation , hydroelectrolysis , and thermal decomposition of various oxides and ...
Oxygenic photosynthesis uses water as an electron donor, which is oxidized to molecular oxygen (O 2) in the photosynthetic reaction center. The biochemical capacity for oxygenic photosynthesis evolved in a common ancestor of extant cyanobacteria. [11] The first appearance of free oxygen in the atmosphere is sometimes referred to as the oxygen ...
X-ray crystal structure of the Mn 4 O 5 Ca core of the oxygen evolving complex of Photosystem II at a resolution of 1.9 Å. [2] The oxygen-evolving complex (OEC), also known as the water-splitting complex, is a water-oxidizing enzyme involved in the photo-oxidation of water during the light reactions of photosynthesis. [3]
The evolution of oxygen during the light-dependent steps in photosynthesis (Hill reaction) was proposed and proven by British biochemist Robin Hill. He demonstrated that isolated chloroplasts would make oxygen (O 2) but not fix carbon dioxide (CO 2). This is evidence that the light and dark reactions occur at different sites within the cell. [1 ...
In 2011 the OEC of PSII was resolved to a level of 1.9Å revealing five oxygen atoms serving as oxo bridges linking the five metal atoms and four water molecules bound to the Mn 4 CaO 5 cluster; more than 1,300 water molecules were found in each photosystem II monomer, some forming extensive hydrogen-bonding networks that may serve as channels ...
Of the two half reactions, the oxidation step is the most demanding because it requires the coupling of 4 electron and proton transfers and the formation of an oxygen-oxygen bond. This process occurs naturally in plants photosystem II to provide protons and electrons for the photosynthesis process and release oxygen to the atmosphere, [ 1 ] as ...
Under low oxygen concentrations and before the evolution of nitrogen fixation, biologically-available nitrogen compounds were in limited supply, [16] and periodic "nitrogen crises" could render the ocean inhospitable to life. [9] Significant concentrations of oxygen were just one of the prerequisites for the evolution of complex life. [9]
X-ray Crystal structure of the Mn 4 O 5 Ca core of the oxygen evolving complex of Photosystem II at a resolution of 1.9 Å. [1] Water oxidation catalysis (WOC) is the acceleration (catalysis) of the conversion of water into oxygen and protons: 2 H 2 O → 4 H + + 4 e − + O 2. Many catalysts are effective, both homogeneous catalysts and ...