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As with the chemical antioxidants, cells are protected against oxidative stress by an interacting network of antioxidant enzymes. [31] [32] Here, the superoxide released by processes such as oxidative phosphorylation is first converted to hydrogen peroxide and then further reduced to give water. This detoxification pathway is the result of ...
Numbering over 4,000 distinct chemical structures mostly from plants, such polyphenols have not been demonstrated to be antioxidants in vivo. [1] [2] [3] In vitro at high experimental doses, polyphenols may affect cell-to-cell signaling, receptor sensitivity, inflammatory enzyme activity or gene regulation.
Polyphenol oxidase is an enzyme found throughout the plant and animal kingdoms, [31] including most fruits and vegetables. [32] PPO has importance to the food industry because it catalyzes enzymatic browning when tissue is damaged from bruising, compression or indentations, making the produce less marketable and causing economic loss.
The cytosols of virtually all eukaryotic cells contain a SOD enzyme with copper and zinc (Cu-Zn-SOD). For example, Cu-Zn-SOD available commercially is normally purified from bovine red blood cells. The bovine Cu-Zn enzyme is a homodimer of molecular weight 32,500. It was the first SOD whose atomic-detail crystal structure was solved, in 1975. [10]
It is an antioxidant in plants, animals, fungi, and some bacteria and archaea. Glutathione is capable of preventing damage to important cellular components caused by sources such as reactive oxygen species, free radicals, peroxides, lipid peroxides, and heavy metals. [2]
DNA repair enzymes include endonuclease IV, induced by oxidative stress, and exonuclease III, induced in the stationary phase and in starving cells. These enzymes act on duplex DNA and clean up DNA 3' terminal ends. Prokaryotic cells contain catalysts that modify the primary structure of proteins frequently by reducing disulfide bonds.
Antioxidants play a crucial role in mitigating lipid peroxidation by neutralizing free radicals, thereby halting radical chain reactions. Key antioxidants include vitamin C and vitamin E . [ 8 ] Additionally, enzymes including superoxide dismutase , catalase , and peroxidase contribute to the oxidation response by reducing the presence of ...
To counteract these reactive oxygen species, cells contain numerous antioxidant systems, including antioxidant vitamins such as vitamin C and vitamin E, and antioxidant enzymes such as superoxide dismutase, catalase, and peroxidases, [81] which detoxify the reactive species, limiting damage to the cell.