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Radical elimination can be viewed as the reverse of radical addition. In radical elimination, an unstable radical compound breaks down into a spin-paired molecule and a new radical compound. Shown below is an example of a radical elimination reaction, where a benzoyloxy radical breaks down into a phenyl radical and a carbon dioxide molecule. [7]
Additionally, enzymes including superoxide dismutase, catalase, and peroxidase contribute to the oxidation response by reducing the presence of hydrogen peroxide, which is a prevalent precursor of the hydroxyl radical (OH•). As an example, vitamin E can donate a hydrogen atom to the lipid hydroperoxyl radical (LOO•) to form a vitamin E ...
The free radical theory of aging states that organisms age because cells accumulate free radical damage over time. [1] A free radical is any atom or molecule that has a single unpaired electron in an outer shell. [2] While a few free radicals such as melanin are not chemically reactive, most biologically relevant free radicals are highly ...
For example, the increase in temperature, drought are factors that limit the availability of CO 2 due to stomatal closure, increasing the production of ROS, such as O 2 ·- and 1 O 2 in chloroplasts. [ 34 ] [ 35 ] The production of 1 O 2 in chloroplasts can cause reprogramming of the expression of nucleus genes leading to chlorosis and ...
In chemistry, peroxides are a group of compounds with the structure R−O−O−R, where the R's represent a radical (a portion of a complete molecule; not necessarily a free radical [1]) and O's are single oxygen atoms. [2] [3] Oxygen atoms are joined to each other and to adjacent elements through single covalent bonds, denoted by dashes or lines.
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]
Autoxidation is therefore a fairly broad term and can encompass examples of photooxygenation and catalytic oxidation. The common mechanism is a free radical chain reaction , where the addition of oxygen gives rise to hydroperoxides and their associated peroxy radicals (ROO•). [ 5 ]
A reaction between these two products results in the formation of a free hydroxyl radical (OH.). [4] Superoxide, hydrogen peroxide, and hydroxyl radicals are a class of compounds known as reactive oxygen species (ROS), highly reactant products that are damaging to microbes, including obligate anaerobes. [4]