Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.5.2 (NQO1)
 6,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Reduction of several nitroso-compounds by purified DT-diaphorase from rat liver cytosol was investigated. Among nitroso-compounds tested, 1-nitroso-2-naphthol and p-nitrosophenol were reduced in the presence of reduced nicotinamide adenine dinucleotide phosphate (NADPH) at rates much faster than that of nitrosobenzene. On the contrary, none of the N-nitroso-compounds tested was reduced by this enzyme. Experiments on the identification of reduction products and on the inhibition with dicoumarol and the antiserum indicated that DT-diaphorase catalyzes 4-electron reduction of C-nitroso-compounds and plays a major role in the reduction of these compounds by rat liver cytosol.
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PMID:Rat liver DT-diaphorase as a nitroso-reductase. 211 41

The extent of ferrihemoglobin formation in human erythrocytes by 4-nitrosophenetol and its metabolisation rate strongly depended on the availability of cellular GSH. Ferrihemoglobin formation rate was increased by inhibition of the red cell glutathione reductase, and 4-nitrosophenetol disappeared more slowly. When red cells were completely depleted from SH groups, ferrihemoglobin formation was retarded, despite 4-nitrosophenetol was hardly metabolized. In turn, the glutathione status of human red cells was strongly affected by 4-nitrosophenetol. GSSG, which was produced in large amounts, was reduced, as long as the reducing system was intact. The decreased total glutathione content, however, did not recover completely, indicating formation of stable glutathione S-conjugates. The active export of the stable model glutathione thioether S-(2,4-dinitrophenyl)glutathione was strongly inhibited by 4-nitrosophenetol. A Lineweaver-Burk plot of the transport data suggested a competitive inhibition mechanism, presumably caused by glutathione adducts. The results indicate that the strong pi-donor substituent in 4-nitrosophenetol enables metabolic reactions with glutathione, producing biological effects hitherto not observed with nitrosobenzene. Bicyclic arylamines and glutathione S-conjugates may cause ferrihemoglobin formation that is not brought about by the diaphorase reaction. The latter may be responsible for transport inhibition of GSSG and other glutathione S-conjugates.
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PMID:Effects of the phenacetin metabolite 4-nitrosophenetol on the glutathione status and the transport of glutathione S-conjugates in human red cells. 843 97