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Oxidative stress mechanisms in tissue injury. Free radical toxicity induced by xenobiotics and the subsequent detoxification by cellular enzymes (termination).. Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. [1]
Oxidation response is stimulated by a disturbance in the balance between the production of reactive oxygen species and antioxidant responses, known as oxidative stress. Active species of oxygen naturally occur in aerobic cells and have both intracellular and extracellular sources.
The relative importance of the antioxidant and pro-oxidant activities of antioxidant vitamins is an area of current research, but vitamin C, for example, appears to have a mostly antioxidant action in the body. [7] [9] However, less data is available for other dietary antioxidants, such as polyphenol antioxidants, [10] zinc, [11] and vitamin E ...
Several grams are produced per day in the human body within the mitochondria. [5] O 2 + e − → O − 2. Competing with its formation, superoxide is destroyed by the action of superoxide dismutases, enzymes that catalyze its disproportionation: 2 O − 2 + 2H + → O 2 + H 2 O 2. hydrogen peroxide (H 2 O 2) is also produced as a side product ...
Sulfur is the third most abundant mineral element in the body. [21] The amino acids cysteine and methionine are used by the body to make glutathione. Excess cysteine and methionine are oxidized to sulfate by sulfite oxidase, eliminated in the urine, or stored as glutathione (which can serve as a store for sulfur). [21]
The major source of NAD + in mammals is the salvage pathway which recycles the nicotinamide produced by enzymes utilizing NAD +. [38] The first step, and the rate-limiting enzyme in the salvage pathway is nicotinamide phosphoribosyltransferase (NAMPT), which produces nicotinamide mononucleotide (NMN). [ 38 ]
The relative importance of the antioxidant and pro-oxidant activities of antioxidants is an area of current research, but vitamin C, which exerts its effects as a vitamin by oxidizing polypeptides, appears to have a mostly antioxidant action in the human body.
In E. coli, for example, oxidative phosphorylation can be driven by a large number of pairs of reducing agents and oxidizing agents, which are listed below. The midpoint potential of a chemical measures how much energy is released when it is oxidized or reduced, with reducing agents having negative potentials and oxidizing agents positive ...