Sulfur-containing compounds oxidized glutathione

Sulfur-containing compounds such as alpha-lipoic acid, methylsulfonylmethane, glutathione, N-acetylcysteine and cysteine are effective against oxidative stress and cell damage caused by free radicals (Bray and Taylor 1993, Pollack et al. 1996). Alpha-lipoic acid increases the antioxidant potency of further antioxidants such as vitamins E and C (Kagan et al. 1992). The course of acute pancreatitis is dramatically impaired in cases of very low antioxidant status. Whereas the sulfur antagonist selenium reduced remarkably the death rate (Kulinski et al. 1995), methionine was also used successfully in the treatment of this disease (Uden et al. 1990). 

It is of interest to note that the thiol form of TPP contains the j3-thiol-ethylamine configuration present in coenzyme A. The fact that glutathione, coenzyme A, and the pyruvate oxidation factor all are sulfur-containing compounds is highly suggestive of the possibility that TPP is also active in the thiol form. Cavallini has recently shown that in vitro at pH 7.4, the oxidation of GSH by oxygen in the presence of traces of copper or cytochrome c may be coupled with a simultaneous oxidation of pyruvate to acetate and CO2. The reaction probably depends on the intermediate formation of a GSH-pyruvate complex and is suggested as a possible model for the action of TPP. 

Selenium is an essential trace element and an integral component of heme oxidase. It appears to augment the antioxidant action of vitamin E to protect membrane lipids from oxidation. The exact mechanism of this interaction is not known however, selenium compounds are found in the selenium analogs of the sulfur-containing amino acids, such as cysteine and methionine. Se-cysteine is found in the active sites of the enzyme glutathione peroxidase, which acts to use glutathione to reduce organic hydroperoxides. 

SuMur compounds compounds containing reduced or oxidized sulfur, seldom both (Table). Biochemically important S.a are the sulfur amino adds (see L-C eine, L-Methionine), biotin (thiophane ting) and thiamin (thiazole ting) (see Vitamins), sul-fatides (complex lipids of the nervous system see dy-colipids), and thiol peptides (see Glutathione, Vasopressin, Oxytodn, Insulin). S.c. also include Penicillin (see), and the sulfonamid which are important synthetic therapeutic agents. Hie mustard oil glycosides contain both oxidiz and reduced sulfur. Sulfate esters (see) are excreted by animals. 

Vitamin Bn-deficient P. shermanii grows well under strictly anaerobic conditions. However, under microaerophilic conditions compounds containing reduced sulfur methionine, cysteine, thiosulfate, reduced glutathione, or tryptone must be added to the medium (Fig. 5.3) (Vorobjeva and Iordan, 1976). These compounds are necessary to prevent the oxidation of thiol groups. A direct determination showed (Iordan et al., 1974) that the... 

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