Hydrogen peroxide catalase action

Burk D, Woods M. Hydrogen peroxide, catalase, glutathione peroxidase, quinones, nordihydroguaiaretic acid, and phosphopyridine nucleotides in relation to x-ray action on cancer cells. RadiatRes 1963 3(Suppl) 212 16. 

Burk, D., and M. Woods Hydrogen Peroxide, Catalase, Glutathione Peroxidase, Quinones, Nor-dihydroguaiaretic Acid, and Phosphopyridine Nucleotides in Relation to X-Ray Action on Cancer Cells. Radiation Res. Suppl. 3, 212 (1963) apud Chem. Abstr. 59, 1934 (1963). 

The hydrogen peroxide produced in the glucose oxidase catalyzed reaction has an antibacterial action. If the presence of hydrogen peroxide is undesirable in the product, catalase is added to remove the peroxide. 

Under most conditions in vivo, the peroxidase activity of catalase seems to be favored. Catalase is found in blood, bone marrow, mucous membranes, kidney, and fiver. Its function is assumed to be the destruction of hydrogen peroxide formed by the action of oxidases. 

Superoxide is formed (reaction 1) in the red blood cell by the auto-oxidation of hemoglobin to methemo-globin (approximately 3% of hemoglobin in human red blood cells has been calculated to auto-oxidize per day) in other tissues, it is formed by the action of enzymes such as cytochrome P450 reductase and xanthine oxidase. When stimulated by contact with bacteria, neutrophils exhibit a respiratory burst (see below) and produce superoxide in a reaction catalyzed by NADPH oxidase (reaction 2). Superoxide spontaneously dismu-tates to form H2O2 and O2 however, the rate of this same reaction is speeded up tremendously by the action of the enzyme superoxide dismutase (reaction 3). Hydrogen peroxide is subject to a number of fates. The enzyme catalase, present in many types of cells, converts... 

Nifurtimox (Lampit) is a nitrofuran derivative whose likely mechanism of action for kUhng of trypanosomes is through the production of activated forms of oxygen. Nifurtimox is reduced to the nitro anion radical, which reacts with oxygen to produce superoxide and hydrogen peroxide. The free radical metabolites, an absence of parasite catalase, and a peroxide dehciency lead to hpid peroxidation and cell damage. This production of activated oxygen results in toxicity to the protozoal cells. 

The hydrogen peroxide produced by SOD is then removed by either catalase action or GSH peroxidase. The products are water and oxygen or water and GSSG (Figs. 6.10 and 6.18). 

The superoxide produced can be detoxified by the action of the enzyme superoxide dismutase, which produces hydrogen peroxide. The hydrogen peroxide is then removed by catalase (Fig. 7.41)... 

The hydrogen peroxide formed is degraded through the action of catalase, or, less often, by one of the peroxidases. Serine and threonine lose nitrogen via dehydratases (lyases see Figures 20.12 and 20.13). 

Ascorbate is also frequently added to the incubation medium to remove hydrogen peroxide formed during a variety of reactions. Again, a number of reducing agents have the same action, and in vivo this role would presumably be performed by catalase. 

The major function of catalase is the decomposition of peroxides, but it can also act as a peroxidase. Catalases usually have molecular wei ts of about 240 000, with four identical subunits. Each subunit contains protoporphyrin IX, with high-spin Fe", and an amino add residue in the axial position. The mechanism of action of catalase involves the oxidation by H2O2 of the Fe catalase to compound I, two equivalents higher in redox state, and its subsequent reduction via compound II. Compound II may be oxidized by hydrogen peroxide to give compound III, which appears to have three oxidizing equivalents above Fe . ... 

Observe the action of catalase on the decomposition of hydrogen peroxide. 

Mammalian systems have an enzyme, superoxide dismutase, which removes superoxide and produces hydrogen peroxide. This reactive product can then be removed by the action of catalase or glutathione peroxidase (see figure 6,10) ... 

The hydrogen peroxide is normally destroyed by catalase and peroxidases, but some may be transformed to OH-, the hydroxyl radical, which is extremely reactive and modifies all biomolecules in its vicinity. Membrane lipids are destroyed. The mode of action of copper salts and paraquat is in many ways the same, although their target organisms are quite different. 

---