Reductases glutathion reductase

DIHYDROOROTATE OXIDASE DIMETHYLANILINE MONOOXYCENASE FERREDOXIN NADP REDUCTASE GLUTATHIONE REDUCTASE 0-2-HYDROXY ACID DEHYDROGENASE... 

Defects in oxidoreductase in erythrocytes (methemoglobin reductase, glutathione reductase, glucose-6-phosphate dehydrogenase Chapter 15). Patients who have these defects usually are not cyanotic unless subjected to oxidative stress (e.g., treatment with primaquine or sulfonamide). 

FIGURE 5.16 The interrelationship between glucose-6-phosphate dehydrogenase (G6PDHase), NADPH, GSH and the reduction of oxidized metabolites. GSSG reductase glutathione reductase GPX glutathione... 

Peroxisomal H2O2 may be enzymatically removed by catalase (2), or non-enzymatically by reaction with giyoxylate to form formate and CO2 (3,4). In the chioropiasts the enzymes ascorbate peroxidase, dehydroascorbate reductase, glutathione reductase and Fd NADP oxidoreductase undergo a series of oxidation-reduction reactions which lead to the breakdown of H2O2 to O2 and H2O and the concomitant production of NADP+ (5,6). 

An en2ymatic method for assessing riboflavin deficiency in humans has been developed (74). It is based on the fact that NADPH-dependent glutathione reductase of red cells reflects riboflavin fluctuations. 

FIGURE 6.34 Sheet structures formed from andparallel arrangements of /3-strands, (a) Streptomyces suh i x Xu inhibitor, (b) glutathione reductase domain 3, and (c) the second domain of glyceraldehyde-3-phosphate dehydrogenase represent minimal andparallel /S-sheet domain structures. In each of these cases, an andparallel /S-sheet is largely exposed to solvent on one face and covered by helices and random coils on the other face. (Jane Richardson)... 

The FAD-dependent enzyme glutathione reductase plays a role in the antioxidant system. Glutathione reductase restores reduced glutathione (GSH), the most important antioxidant in erythrocytes, from oxidized glutathione (GSSG) [1, 2]. 

Figure 45-6. Interaction and synergism between antioxidant systems operating in the lipid phase (membranes) of the cell and the aqueous phase (cytosol). (R-,free radical PUFA-00-, peroxyl free radical of polyunsaturated fatty acid in membrane phospholipid PUFA-OOH, hydroperoxy polyunsaturated fatty acid in membrane phospholipid released as hydroperoxy free fatty acid into cytosol by the action of phospholipase Aj PUFA-OH, hydroxy polyunsaturated fatty acid TocOH, vitamin E (a-tocopherol) TocO, free radical of a-tocopherol Se, selenium GSH, reduced glutathione GS-SG, oxidized glutathione, which is returned to the reduced state after reaction with NADPH catalyzed by glutathione reductase PUFA-H, polyunsaturated fatty acid.)...

Although riboflavin is fundamentally involved in metabolism, and deficiencies are found in most countries, it is not fatal as there is very efficient conservation of tissue riboflavin. Riboflavin deficiency is characterized by cheilosis, lingual desquamation and a seborrheic dermatitis. Riboflavin nutritional status is assessed by measurement of the activation of erythrocyte glutathione reductase by FAD added in vitro. 

Kar, N.C. and Pearson, C.M. (1979). Catalase superoxide dismutase, glutathione reductase and thiobarbituric acid-reactive products in normal and dystrophic human muscle. Clin. Chim. Acta 94, 277-280. 

Glutathione reductase (GR) catalyzes the reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH) using NADPH provided from the hexose monophosphate pathway. GR, a ubiquitous flavoenzyme, maintains a high value of two for the GSH/GSSG ratio in the red blood cells. l,3-Bis(2-chloroethyl)-nitrosourea (BCNU) selectively inhibits cellular GR. GR is composed of two identical subunits, each of molecular mass 50 kDa (S8). The three-dimensional structure and mechanism of catalysis have been established for human GR (K17). 

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