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Radicals are either (1) formed from spin-paired molecules or (2) from other radicals. Radicals are formed from spin-paired molecules through homolysis of weak bonds or electron transfer, also known as reduction. Radicals are formed from other radicals through substitution, addition, and elimination reactions.
The hydroxyl radical can damage virtually all types of macromolecules: carbohydrates, nucleic acids , lipids (lipid peroxidation) and amino acids (e.g. conversion of Phe to m-Tyrosine and o-Tyrosine). The hydroxyl radical has a very short in vivo half-life of approximately 10 −9 seconds and a high reactivity. [5]
The cytotoxic nature of ROS is a driving force behind apoptosis, but in even higher amounts, ROS can result in both apoptosis and necrosis, a form of uncontrolled cell death, in cancer cells. [ 70 ] Numerous studies have shown the pathways and associations between ROS levels and apoptosis, but a newer line of study has connected ROS levels and ...
For example, the SF 5 radical formed by the reaction of solvated electrons and SF 6 undergo further reactions which lead to the formation of hydrogen fluoride and sulfuric acid. [ 22 ] In water, the dimerization reaction of hydroxyl radicals can form hydrogen peroxide , while in saline systems the reaction of the hydroxyl radicals with chloride ...
In free radical polymerization, radicals formed from the decomposition of an initiator molecule are surrounded by a cage consisting of solvent and/or monomer molecules. [6] Within the cage, the free radicals undergo many collisions leading to their recombination or mutual deactivation. [5] [6] [9] This can be described by the following reaction:
Particularly important is the reduction of coenzyme Q in complex III, as a highly reactive ubisemiquinone free radical is formed as an intermediate in the Q cycle. This unstable species can lead to electron "leakage" when electrons transfer directly to oxygen, forming superoxide. [ 85 ]
In chemistry, a superoxide is a compound that contains the superoxide ion, which has the chemical formula O − 2. [1] The systematic name of the anion is dioxide(1−).The reactive oxygen ion superoxide is particularly important as the product of the one-electron reduction of dioxygen O 2, which occurs widely in nature. [2]
Example radical: Structure of Hydrocarboxyl radical, lone electron indicated as single black dot. A radical is a molecule with an odd number of electrons, and is induced in a variety of ways, including ultraviolet radiation. A sun burn is largely due to radical formation from this radiation. The radical-pair, however, is not simply two radicals.