Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.99.3 (diaphorase)
 5,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Nitrate induces the development of NADH-nitrate reductase (EC 1.6.6.1), FMNH(2)-nitrate reductase and NADH-cytochrome c reductase activities in barley shoots. 2. Sucrose-density-gradient analysis shows one band of NADH-nitrate reductase (8S), one band of FMNH(2)-nitrate reductase activity (8S) and three bands of NADH-cytochrome c reductase activity (bottom layer, 8S and 3.7S). Both 8S and 3.7S NADH-cytochrome c reductase activities are inducible by nitrate, but the induction of the 8S band is much more marked. 3. The 8S NADH-cytochrome c reductase band co-sediments with both NADH-nitrate reductase activity and FMNH(2)-nitrate reductase activity. Nitrite reductase activity (4.6S) did not coincide with the activity of either the 8S or the 3.7S NADH-cytochrome c reductase. 4. FMNH(2)-nitrate reductase activity is more stable (t((1/2)) 12.5min) than either NADH-nitrate reductase activity (t((1/2)) 0.5min) or total NADH-cytochrome c reductase activity (t((1/2)) 1.5min) at 45 degrees C. 5. NADH-cytochrome c reductase and NADH-nitrate reductase activities are more sensitive to p-chloromercuribenzoate than is FMNH(2)-nitrate reductase activity. 6. Tungstate prevents the formation of NADH-nitrate reductase and FMNH(2)-nitrate reductase activities, but it causes superinduction of NADH-cytochrome c reductase activity. Molybdate overcomes the effects of tungstate. 7. The same three bands (bottom layer, 8S and 3.7S) of NADH-cytochrome c reductase activity are observed irrespective of whether induction is carried out in the presence or absence of tungstate, but only the activities in the 8S and 3.7S bands are increased. 8. The results support the idea that NADH-nitrate reductase, FMNH(2)-nitrate reductase and NADH-cytochrome c reductase are activities of the same enzyme complex, and that in the presence of tungstate the 8S enzyme complex is formed but is functional only with respect to NADH-cytochrome c reductase activity.
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PMID:Structural and functional relationships of enzyme activities induced by nitrate in barley. 432 54

Water compartments, permeability, and the possible active translocation of various substances in rat liver microsomes were studied by using radioactive compounds and ultracentrifugation. The total water of the microsomal pellet, 3.4 microl/mg dry weight, is the sum of water in the extramicrosomal and intramicrosomal spaces, or 56 and 44%, respectively. Sucrose space accounts for 77% of the intramicrosomal water and the hydration water approximately 14%, leaving almost no sucrose-impermeable space when using the ultracentrifugation approach. With increasing sucrose concentration, microsomes do not show an osmotic response. The intramicrosomal water decreases greatly in the presence of Cs(+) and Mg(++) in rough but not in smooth microsomes. Uncharged substances of molecular weight of up to at least 600 freely penetrate microsomal membranes, which already become impermeable to charged substances at a molecular weight of 90. These substances also induce an osmotic response. The vesicles can be made permeable to charged substances after water treatment and cooling, which, however, does not increase glucose-6-phosphatase and inosine diphosphatase (IDPase) activities, and these enzymes can still be activated by deoxycholate. IDPase, reduced nicotinamide adenine dinucleotide-cytochrome c reductase, and reduced nicotinamide adenine dinucleotide phosphate-dependent hydroxylation reactions, performed in vitro, also disproved the hypothesis of an accumulation of charged substances inside of vesicles of being a major pathway. The products of the enzymic reactions as well as the glucuronidated form of a hydroxylated product can be recovered on the cytoplasmic side of membranes, and little accumulation occurs in the intravesicular compartment.
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PMID:Permeability of microsomal membranes isolated from rat liver. 440 88

When isolated rat myometrium vesicles highly enriched in plasma membranes were preincubated with 100 mM NaCl and then diluted 21-fold in Na-free media, an ATP-independent Ca uptake value of 4.10 +/- 0.23 mumol/g protein occurred, compared to a value of 2.87 +/- 0.16 for a similar uptake by vesicles preincubated in Na-free media. Brief (less than 10 s) exposure of the membrane vesicles to 5 mM ethyleneglycol-bis(beta-aminoethyl)-N,N'-tetraacetic acid (EGTA) after the Ca uptake showed that the NaCl preincubated vesicles retained more Ca than the sucrose or KCl preincubated vesicles. A NaCl concentration in the membrane fractions identical to its concentration in the Ca uptake medium did not enhance the Ca uptake by the vesicles did not show an increased Ca uptake. NaCl added to plasma membrane vesicles actively loaded with Ca caused retention of less Ca than the control. NaCl added to actively loaded vesicles along with EGTA also enhanced calcium efflux compared to EGTA alone. Sucrose, K+, Rb+, or Cs+ could not replace Na+ for the Na+-dependent Ca uptake or release, while Li+ was a poor substitute in both the instances. Na+-dependent Ca-uptake distribution in the various fractions correlated very well with their 5'-nucleotidase activity but not with their NADPH- or succinate-dependent cytochrome c reductase activities. The results have been discussed using a Na--Ca exchange model as well as by a model in which Na+ competes for calcium binding to the membranes.
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PMID:Na--Ca exchange in rat myometrium membrane vesicles highly enriched in plasma membranes. 723