 Mechanism of lipid peroxidation. Lipid peroxidation refers to the oxidative degradation of lipids. It is the process whereby free radicals "steal" electrons from the lipids in cell membranes, resulting in cell damage. This process proceeds by a free radical chain reaction mechanism. It most often affects polyunsaturated fatty acids, because they contain multiple double bonds in between which lie methylene -CH2- groups that possess especially reactive hydrogens. As with any radical reaction the reaction consists of three major steps: initiation, propagation and termination. Image File history File links No higher resolution available. ...
Image File history File links No higher resolution available. ...
Illustration of a redox reaction Redox (shorthand for oxidation/reduction reaction) describes all chemical reactions in which atoms have their oxidation number (oxidation state) changed. ...
A polyunsaturated triglyceride. ...
In chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons on an otherwise open shell configuration. ...
Drawing of a cell membrane A component of every biological cell, the cell membrane (or plasma membrane) is a thin and structured bilayer of phospholipid and protein molecules that encapsulate the cell. ...
Vapours of hydrogen chloride in a beaker and ammonia in a test tube meet to form a cloud of a new substance, ammonium chloride A chemical reaction is a process that results in the interconversion of chemical substances. ...
A polyunsaturated organic compound is one in which more than one double bond exists within the representative molecule. ...
In chemistry, especially biochemistry, a fatty acid is a carboxylic acid (or organic acid), often with a long aliphatic tail (long chains), either saturated or unsaturated. ...
In chemistry, methylene is a divalent functional group CH2 derived formally from methane. ...
General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ...
Initiation
Initiation is the step whereby a fatty acid radical is produced. The initiators in living cells are most notably reactive oxygen species (or ROS), such as OH°, which combines with a hydrogen atom to make water and a fatty acid radical. General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ...
Propagation The fatty acid radical is not a very stable molecule, so it reacts readily with molecular oxygen, thereby creating a peroxyl-fatty acid radical. This too is an unstable species that reacts with another free fatty acid producing a different fatty acid radical and a hydrogen peroxide or a cyclic peroxide if it had reacted with itself. This cycle continues as the new fatty acid radical reacts in the same way. 3D (left and center) and 2D (right) representations of the terpenoid molecule atisane. ...
Hydrogen peroxide (H2O2) is a very pale blue liquid which appears colourless in a dilute solution, slightly more viscous than water. ...
Termination When a radical reacts it always produces another radical, which is why the process is called a "chain reaction mechanism." The radical reaction stops when two radicals react and produce a non-radical species. This happens only when the concentration of radical species is high enough for there to be a high probability of two radicals actually colliding. Living organisms have evolved different molecules to catch free radicals and protect the cell membrane. One important such antioxidant is alpha-tocopherol, also known as vitamin E. Other anti-oxidants made within the body include the enzymes superoxide dismutase, catalase, and peroxidase. α-Tocopherol (Vitamin E) Tocopherol, or Vitamin E, is a fat-soluble vitamin in eight forms that is an important antioxidant. ...
Tocopherol, or Vitamin E, is a fat-soluble vitamin in eight forms that is an important antioxidant. ...
Structure of the monomeric unit of human superoxide dismutase 2 The enzyme superoxide dismutase (SOD, EC 1. ...
Catalase (human erythrocyte catalase: PDB 1DGF, EC 1. ...
Glutathione Peroxidase 1 A peroxidase (eg. ...
Tests Certain diagnostic tests are available for the quantification of the end products of lipid peroxidation, specifically Malondialdehyde (MDA). The most commonly used test is called a TBARS Assay.
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