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The fact that a reaction is thermodynamically possible does not mean that it will actually occur. A mixture of hydrogen gas and oxygen gas does not spontaneously ignite. It is necessary either to supply an activation energy or to lower the intrinsic activation energy of the system, in order to make most biochemical reactions proceed at a useful ...
A photooxygenation is a light-induced oxidation reaction in which molecular oxygen is incorporated into the product(s). [ 1 ] [ 2 ] Initial research interest in photooxygenation reactions arose from Oscar Raab's observations in 1900 that the combination of light, oxygen and photosensitizers is highly toxic to cells. [ 3 ]
In chemical thermodynamics, an endergonic reaction (from Greek ἔνδον (endon) 'within' and ἔργον (ergon) 'work'; also called a heat absorbing nonspontaneous reaction or an unfavorable reaction) is a chemical reaction in which the standard change in free energy is positive, and an additional driving force is needed to perform this ...
After being carried in blood to a body tissue in need of oxygen, O 2 is handed off from the heme group to monooxygenase, an enzyme that also has an active site with an atom of iron. [9] Monooxygenase uses oxygen for many oxidation reactions in the body. Oxygen that is suspended in the blood plasma equalizes into the tissue according to Henry's law.
Start points of arrows indicate energy associated with half-cell reaction. Lengths of arrows indicate an estimate of Gibb's free energy (ΔG) for the reaction where a higher ΔG is more energetically favorable (Adapted from Libes, 2011). [3] A redox gradient is a series of reduction-oxidation reactions sorted according to redox potential.
Syntrophy, in the context of microbial metabolism, refers to the pairing of multiple species to achieve a chemical reaction that, on its own, would be energetically unfavorable. The best studied example of this process is the oxidation of fermentative end products (such as acetate, ethanol and butyrate ) by organisms such as Syntrophomonas .
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 ...
Molecular oxygen serves as the terminal electron acceptor in the series of biochemical reactions known as oxidative phosphorylation that are ultimately responsible for the synthesis of adenosine triphosphate, the main source of energy for otherwise thermodynamically unfavorable cellular processes. [2]