Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q8NEX9 (reductase)
 26,410 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Biliverdin reductase was purified from pig spleen soluble fraction to a purity of more than 90% as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme was a monomer protein with a molecular weight of about 34,000. Its isoelectric point was at 6.1-6.2. The enzyme was strictly specific to biliverdin and no other oxiodoreductase activities could be detected in the purified enzyme preparation. The purified enzyme could utilize both NADPH and NADH as electron donors for the reduction of biliverdin. However, there were considerable differences in the kinetic properties of the NADPH-dependent and the NADH-dependent biliverdin reductase activities: Km for NADPH was below 5 microM while that for NADH was 1.5-2 mM; the pH optimum of the reaction with NADPH was 8.5 whereas that of the reaction with NADH was 6.9; Km for biliverdin in the NADPH system was 0.3 microM whereas that in the NADH system was 1-2 microM. In addition, both the NADPH-dependent and NADH-dependent activities were inhibited by excess biliverdin, but this inhibition was far more pronounced in the NADPH system than in the NADH system. IX alpha-biliverdin was the most effective substrate among the four biliverdin isomers, and the dimethylester of IX alpha-biliverdin could not serve as a substrate. Biliverdin reductase was also purified about 300-fold from rat liver soluble fraction. The hepatic enzyme was also a monomer protein with a molecular weight of 34,000 and showed properties quite similar to those of the splenic enzyme as regards the biliverdin reductase reaction. The isoelectric point of the hepatic enzyme, however, was about 5.4. It was assumed that NADPH rather than NADH is the physiological electron donor in the intracellular reduction of IX alpha-biliverdin. The stimulatory effects of bovine and human serum albumins on the biliverdin reductase reactions were also examined.
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PMID:Purification and properties of biliverdin reductases from pig spleen and rat liver. 4 Sep 68

Two NADPH-dependent aromatic aldehyde-ketone reductases purified from guinea pig liver catalyzed oxidoreduction of 17 beta-hydroxysteroids and 17-ketosteroids. One enzyme efficiently oxidized 5 beta-androstanes and reduced 17-ketosteroids of A/B cis configuration, whereas the other enzyme efficiently oxidized 5 alpha-androstanes and equally reduced both 5 alpha-and 5 beta-androstanes of 17-ketosteroids. However, aromatic aldehydes and ketones, and 3-ketosteroids were irreversibly reduced by the two enzymes. The two enzymes utilized NADP+ or NADPH as cofactor, but little activity with NAD+ or NADH was found. Phosphate ions enhanced the NAD+-dependent dehydrogenase activity and NADH-dependent reductase activity of the two enzymes, whereas the activities with NADP+ and NADPH were not affected. The ratios of the two activities of ketone reduction and 17 beta-hydroxysteroid oxidation of the two enzymes were almost constant during the purification steps after the two enzymes had been separated by DEAE-cellulose chromatography. By kinetic studies and electrophoresis and isoelectric focusing experiments it was confirmed that both of the two enzymes were responsile for the reduction aldehydes, ketones, and ketosteroids and for the oxidation of 17 beta-hydroxysteroids. These results indicate that 17 beta-hydroxysteroid dehydrogenases may play important roles in the metabolism of exogeneous aldehydes and ketones as well as steroids.
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PMID:Guinea pig liver aromatic aldehyde-ketone reductases identical with 17 beta-hydroxysteroid dehydrogenase isozymes. 4 Sep 69

The in vitro metabolism of the antitumor anthracycline antibiotic, aclacinomycin-A, was studied using rat liver homogenate. In the presence of NADH or NADPH, aclacinomycin-A was converted to aclacinomycin-A analogs, MA144 M1 and MA144 N1, which were stereospecifically reduced at the keto group of the C-4''' position of L-cinerulose in aclacinomycin-A. Subcellular fractionation indicated that the production of MA144 M1, which was reduced to L-amicetose, was catalyzed by NADPH-dependent soluble cinerulose reductase I, and the production of MA144 N1, which was reduced to L-rhodinose, was catalyzed by NADPH-dependent soluble cinerulose reductase II and NADH-dependent microsomal cinerulose reductase. The properties of these three enzymes were studied. Soluble cinerulose reductase I which produces MA144 M1 showed a optimum pH at 6.3, Km values of 3.3 x 10(-4) M for aclacinomycin-A and 3.2 x 10(-5) M for NADPH. Soluble cinerulose reductase II which produces MA144 N1 showed a pH optimum at 6.3 and Km values of 2.0 x 10(-3) M for aclacinomycin-A and 4.0 x 10(-5) M for NADPH. All thesse reductases were sensitive to sulfhydryl reagents and were inhibited by vitamin K3. Microsomal cinerulose reductase showed sensitivity to diconmarol and ferrous ion. The main nondegradative pathways of aclacinomycin-A were discussed from these results.
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PMID:Reduction of cinerulose in aclacinomycin-A by soluble and microsomal cinerulose reductases. 4 94

The in vitro degradation of the new antitumor anthracycline antibiotic, aclacinomycin-A, was studied using rat liver homogenate. In the presence of NADH or NADPH, the glycosidic bond at C-7 position of aclacinomycin-A was reductively cleaved to produce 7-deoxyaklavinone and 7-deoxyaklavinone dimer, MA144 E1. Subcellular fractionation indicated that most of the enzyme activity was present in the microsomal fraction and required anaerobic condition and NADPH. The purified enzyme reduced the glycosidic metabolites, MA144 M1 and MA144 N1, as well as aclacinomycin-A. The optimum pH for the anthracycline glycoside reductase reaction using aclacinomycin-A as substrate was 7.4. The enzyme was sigmoidally saturated with aclacinomycin-A and showed the concentration of 1.2 x 10(-4) M required for half maximal activity, and Km value of 7.7 x 10(-5) M for NADPH. The degradative pathway of aclacinomycin-A and its glycosidic metabolites was discussed.
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PMID:Reduction of anthracycline glycoside by NADPH--cytochrome P-450 reductase. 4 95

NAD(P)H: FMN oxidoreductase (flavin reductase) couples in vitro to bacterial luciferase. This reductase, which is also postulated to supply reduced flavin mononucleotide in vivo as a substrate for the bioluminescent reaction, has been partially purified and characterized from two species of luminous bacterial. From Photobacterium fischeri the enzyme has a M. W. determined by Sephadex gel filtration, of 43,000 and may have a subunit structure. The turnover number at 20 degrees C, based on a purity estimate of 20 percent, is 1.7 times 10-4 moles of NADH oxidized per min per mole of reductase. The reductase isolated from Beneckea harveyi has an apparent molecular weight of 23,000; its purity was too low to permit estimation of specific activity. Using a spectrophotometric assay at 340 nm with the P. fischeri reductase, both NADH (Km, 8 times 10-5 M) and NADPH (Km, 4 times 10-4 M) were enzymatically oxidized, the Vmax with NADH being approximately twice that of NADPH. Of the flavins tested in this assay, only FMN (Km, 7.3 times 10-5 M) and FAD (Km, 1.4 times 10-4 M) were effective, FMN having a Vmax three times that of FAD. In the coupled assay, i.e., measuring the bioluminescence intensity of the reaction with added luciferase, the optimum FMN concentration was nearly 100 times less than in the spectrophotometric assay. The studies reported suggest the existence of a functional reductase-luciferase complex.
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PMID:Flavin mononucleotide reductase of luminous bacteria. 4 4

Embryonal rhabdomyosarcomas from the nasopharynx of two children were examined by histochemical methods commonly applied to muscle biopsies. These stains included nicotinamide adenine dinucleotide-tetrazolium reductase (NADH-TR), succinate dehydrogenase (SDH), PAS, PAS-diastase, myophosphorylase, calcium-mediated adenosine triphosphatase (ATPase) preincubated at high and low pH, and oil red O. Myofibrils were easily identified with ATPase and blood vessel walls were also stained. NADH-TR clearly showed longitudinal and cross-striations that were not seen with H&E or PTAH stains. The modified Gomori trichrome stain additionally contributed to the recognition of myofibrils. Some techniques of muscle histochemistry applied to fresh frozen sections of tumor tissue may provide evidence of muscular differentiation in otherwise poorly differentiated sarcomas for a more accurate diagnosis of rhabdomyosarcoma.
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PMID:Diagnostic value of histochemistry in embryonal rhabdomyosarcoma. 9 52

The distribution of 4-nitroquinoline 1-oxide (4-NQO) reductase, assumed to be closely related to the carcinogenesis of 4-NQO, was investigated in the mucosa of canine digestive tract, and its results indicated following points. 1) The activity of 4-NQO reductase was highest in the esophagus, next in the stomach, and remarkably low in the small and large intestines. 2) There is no significant difference in the 4-NQO reductase activity between the upper, middle, and lower portion of the esophagus, but its activity was higher in the female than in the male in its upper and middle portions. 3) Among the esophageal tissue, its activity was high only in the mucous epithelium and very low in all other layers. 4) Most of the enzymic activity in the esophageal mucosa existed in the cytosol fraction and activity of the microsome fraction was remarkably low. Even if NADPH or NADH was used as the hydrogen donor, its activity was not different in the cytosol fraction, but the former was a better hydrogen donor in the microsome fraction. 5) In the gastric mucosa, the enzymic activity was equally high in various portions of the corpus ventriculi; the greater and lesser curvatures, anterior and posterior parietes, and fundus. It was remarkably low only in the pyloric antrum.
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PMID:Distribution of 4-nitroquinoline 1-oxide reductase in the mucosa of canine digestive tract. 9 82

Cytochrome b5 was isolated from liver microsomes using a detergent-method. The hemoprotein was found to bind to liver plasma membranes in vitro and was accompanied by an increase in NADH-cytochrome c reductase activity, but not NADH-ferricyanide reductase activity. As in the case of microsomes, the binding to plasma membranes was temperature-dependent and was tight to the extent that the bound cytochrome b5 was little released under high ionic strength. The capacity of plasma membranes for the binding was less than that of microsomes. Administration of CCl4 did not significantly affect the binding of the hemoprotein in both fractions. These results add support to our previous proposal that the elevation of NADH-cytochrome c reductase activity of liver plasma membranes observed early after administration of CCl4 may be caused by the binding of cytochrome b5 which has probably migrated from the endoplasmic reticulum.
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PMID:Studies on the function of cell membrane. 11th Report: Binding of cytochrome b5 to liver microsomes and plasma membranes isolated from normal and CCl4-treated rats. 9 90

Examination of selected oxidoreductases (succinate dehydrogenase, mitochondrial glycerol-3-phosphate dehydrogenase, lactate dehydrogenase, NADH tetrazolium reductase) in the rat gastric mucosa revealed diurnal fluctation of enzyme activities with the most marked manifestation in succinate dehydrogenase. The maximum enzymatic activity found at 18.00 h and 24.00 h) points to the highest oxidoreductase capacity in the parietal cells just at the time when a rat usually expresses spontaneously the highest interest in food intake. The high activity of succinate dehydrogenase and other enzymes at that time is very likely the expression of a "fixed" metabolic adaptation of the parietal cells to the elevated production of hydrochloric acid, in connection with its role in the digestion of food in the stomach. The low enzymatic activity of most rat parietal cells during the day may represent the picture of "a resting afunctional".
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PMID:Circadian rhythms of oxidoreductases in the rat gastric mucosa. Histochemical study. 9 61

Studies were conducted to determine the in vivo effect of acetaminophen (AAP) on the lipid peroxidation, drug metabolizing enzyme activity and microsomal electron transfer system of rat and mouse liver. AAP was found to inhibit ethylmorphine N-demethylase activity in the presence of NADPH and this inhibition of the enzyme was due to decrease in cytochrome P-450 content, but not due to change in lipid peroxidation in liver microsomes. Kinetical data showed that AAP administration had no effect on Km values of ethylmorphine N-demethylase, however, a decrease in the Vmax values was seen in rats and mice. There was no significant effect of AAP on both NADPH-cytochrome c reductase and the content of cytochrome b5 3 hours after this administration to rats and mice. On the other hand, AAP induced a significant decrease in NADH-ferricyanide reductase in mice, but not in rats. The greatest decrease in cytochrome P-450 observed among the components of the liver microsomal electron transfer system of rats and mice.
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PMID:Comparison of effects of acetaminophen on liver microsomal drug metabolism and lipid peroxidation in rats and mice. 10 Jun 39


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