Oxidizing agents superoxides

Oxygen is converted to the oxidizing agent superoxide anion (Oy) by cellular NADPH oxidase systems (prinicipally in phagocytes) and by xanthine oxidase (Figure 27.10). Hydrogen peroxide (H202) is formed by the further oxidation of Oy by superoxide dismutase (SOD) ... 

C20-0084. In superoxide dismutase it is the Cu center that oxidizes 0. Why is copper more suitable than the center for the role of the oxidizing agent in SOD ... 

Figure 6.20 Oxidation of (a) methionine and (b) cysteine side chains, as can occur upon exposure to air or more potent oxidizing agents (e.g. peroxide, superoxide, hydroxyl radicals or hypochlorite). Refer to text for specific details...

The reaction of superoxide ion with carbon tetrachloride is important for olefin epoxidations. This reaction includes the formation of the trichloromethyl peroxide radical Oj" + CCI4 —> Cl + CI3COO. The trichloromethyl peroxide radicals formed oxidize electron-rich olefins. The latter gives the corresponding epoxides. This peroxide radical is a stronger oxidizing agent than the superoxide ion itself (Yamamoto et al. 1986). 

Besides LPS, other particulate and soluble agents are known to stimulate the formation of eicosanoids, e.g. PGE2, PGD2, and thromboxane [57]. These agents also elicit nitric oxide and superoxide anion formation, which may help to destroy phagocytosed microorganisms or particles [58]. 

In this reaction (demonstrated in vitro), one of the two radicals is oxidizing while the other is reducing. In vivo, this reaction is catalyzed by one of several isoforms of an enzyme known as superoxide dismutase (SOD). As shown above, hydrogen peroxide may form as a result of the superoxide anion s dismutation reaction however, it may also be produced from a bivalent reduction of 02. The addition of the second electron leads to the formation of hydrogen peroxide, which is a powerful oxidizing agent. Due to the unpaired electrons in their outer shells, free radicals are favored to pair with other molecules during bimolecular collisions. 

Potassium superoxide, KO2, is a canary yellow solid that melts at 450-500cC when pure, Potassium superoxide, a strong oxidizing agent, is... 

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