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)

Proteindisulphide reductase is isolated and partially purified from wheat seedlings and some properties of the enzyme are studied: pH optimum is 7.4; temperature optimum - 37 degrees C; Km = 2.6-10(-4)M for the substrate (wheat albumin); Km = 7.5-10(-5) M for coenzyme (NADP-H). The enzyme is specific for NADP-H and is not active in the presence of NAD-H. Maximal activity of proteindisulphide reductase is developed in anaerobic conditions. A technique of the estimation of proteindisulphide reductase activity using wheat albumin as a substrate is worked out. The enzyme activity decreases regularly in the corn ripening and increases under germination. It is accompanied by the respective increase or decrease in the amount of disulphide bonds in gluten protein and by changes of physico-chemical characteristics of gluten. Incubation of gluten with the enzyme preparation affects reological properties of gluten (it becomes weaker) and decreases the gluten viscosity of gluten solution.
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PMID:[Wheat protein disulfide reductase]. 0 Nov 6

In a continuing study of the biosynthetic pathway and regulatory mechanisms governing indole-3-acetic acid (auxin) formation, we report the isolation and initial characterization of three distinct indole-3-acetaldehyde reductases from cucumber seedlings. These enzymes catalyze the reduction of indole-3-acetaldehyde to indole-3-ethanol with the concomitant oxidation of NAD(P)H to NAD(P)+. Two of the reductases are specific for NADPH as second substrate, while the third is specific for NADH. The enzymes show a strong specificity for indoleacetaldehyde, with apparent Km values of 73mum, 130mum, and 400mum being calculated for the two NADPH-specific reductases and the NADH-specific reductase, respectively. Under no conditions of substrate concentration, incubation time, or assay method could the reverse reaction be observed. Chromatography on a calibrated Sephadex gel column led to estimated molecualr weights of 52,000 and 17,000 for the NADPH-specific reductases, while a value of 33,000 was obtained for the NADH-specific reductase. Both NADPH-specific reductases showed a pH optimum of 5.2 with a secondary optimum at 7.0, and both enzymes were activated by increasing ionic strength. The NADH-specific reductase showed a pH optimum of 7.0 with a secondary optimum at 6.1 and was slightly inhibited by increasing ionic strength.
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PMID:Isolation and characterization of indole-3-acetaldehyde reductases from Cucumis sativus. 0 7

The purified respiratory chain NADH dehydrogenase of Escherichia coli oxidizes NADH with either dichlorophenolindophenol (DCIP). ferricyanide, or menadione as electron acceptors, with values for NADH are similar with the three electron acceptors (approximately 50 muM). The purified enzyme contains no flavin and has an absolute requirement for FAD, with Km values around 4 muM. The pH optimum of the enzyme appears to be between 6.5 and 7; the optimum is difficult to establish because of nonenzymatic reduction of DCIP at the lower pH values. Potassium cyanide stimulates the DCIP reductase activity about 2-fold, but has no effect on ferricyanide reductase. The enzyme exhibits hyperbolic kinetics with respect to NADH concentration in both the ferricyanide and DCIP reductase assays, but cooperatively is seen in the menadione reductase reaction. NAD+ is an effective competitive inhibitor of the reaction (Ki congruent to 20 muM); in the presence of NAD+, the NADH saturation curve becomes cooperative, even in the DCIP reductase assay. Many adenine containing nucleotides are competitive inhibitors of the enzyme. The apparent Ki values for these nucleotides as inhibitors of the purified enzyme, the membrane-bound NADH dehydrogenase, and the NADH oxidase are equivalent. An examination of inhibitory effects of a series of adenine nucleotides suggests that the inhibitors act as analogues of NAD+, which is the true physiological inhibitor. The results suggest that the enzyme in situ is always partially inhibited by the levels of NAD- in the E coli cell, and thus behaves in a cooperative fashion to changes in the NAD+/NADH ratio. An antibody has been elicited against the purified NADH dehydrogenase. Immunodiffusion and crossed immunoelectrophoresis show that the antibody is directed principally against the NADH dehydrogenase, with some activity against minor contaminants in the purified preparation. The antibody inhibits NADH dehydrogenase activity 50% at saturating levels. When this antibody preparation is used to examine solubilized membrane preparations, two major immunoprecipitates are found. A parallel inhibition of the membrane-bound NADH dehydrogenase and NADH oxidase activities is seen, supporting the hypothesis that the purified enzyme is indeed a component of the respiratory chain-dependent NADH oxidase pathway.
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PMID:The NADH dehydrogenase of the respiratory chain of Escherichia coli. II. Kinetics of the purified enzyme and the effects of antibodies elicited against it on membrane-bound and free enzyme. 0 8

delta1-Pyrroline-5-carboxylate (PCA) reductase [L-proline:NAD(P)+5-oxidoreductase, EC 1.5.1.2] has been purified over 200-fold from Escherichia coli K-12. It has a molecular weight of approximately 320,000. PCA reductase mediates the pyridine nucleotide-linked reduction of PCA to proline but not the reverse reaction (even at high substrate concentrations). The partially purified preparation is free of competing pyridine nucleotide oxidase, PCA dehydrogenase, and proline oxidase activities. The Michaelis constant (Km) values for the substrate, PCA, with reduced nicotinamide adenine dinucleotide phosphate (NADPH) or NADH as cofactor are 0.15 and 0.14 mM, respectively. The Km values determined for NADPH and NADH are 0.03 and 0.23 mM, respectively. Although either NADPH or NADH can function as cofactor, the activity observed with NADPH is severalfold greater. PCA reductase is not repressed by growth in the presence of proline, but it is inhibited by the reaction end products, proline and NADP.
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PMID:Partial purification and some properties of delta1-pyrroline-5-carboxylate reductase from Escherichia coli. 1 33

Liver endoplasmic membrane contains two hemoproteins, cyt. P-450 and cyt. b5. Cytochrome P-450 catalyzes the hydroxylation of lipid-soluble compounds, while the cyt. b5 system is involved in desaturation of fatty acids. NAD(P)H and oxygen are essential components for both systems. Oxidation of ethanol to acetate in the liver, via alcohol and acetaldehyde dehydrogenases, leads to an elevated cellular NADH content. It has been proposed that oxidation of the cytosolic NADH occurs predominantly in the mitochondria via the substrate oxidation-reduction shuttle. In order to investigate the effects of elevated levels of cytosolic NADH on the state of the endoplasmic hemoprotein system, microsomes from a fatty human liver (post-ethanol intake) were isolated and studied. Microsomal cyt. b5 reductase was found to reoxidize cytoplasmic NADH directly and transfer the reducing equivalents readily to the microsomal oxidases. Addition of catalytic amounts of alcohol dehydrogenase, NAD, and ethanol to microsomes resulted in a rapid reduction of microsomal cyt. b5. These results are consistent with the proposal that the catalytic moiety of cyt. b5 reductase is exposed to the aqueous phase of the membrane and directly accepts reducing equivalents from the cytoplasm. Microsomes from fatty human liver showed an increased rate of cyt. b5 dependent desaturation of fatty acids. These findings suggest that ethanol metabolism may selectively affect the activity of one or the other microsomal hemoprotein. Thus, when the desaturase activity is low, drug metabolism by the cyt. P-450 pathway may predominate. Conversely, an increase in the desaturase level may lead to a decreased drug metabolism. This mechanism may underlie the clinical observations of drug intolerance reactions associated with alcohol intake.
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PMID:The role of microsomal cytochrome b5 in the metabolism of ethanol, drugs and the desaturation of fatty acids. 1 14

The authors compared the enzyme histochemical activities of some dehydrogenases in the macula densa, the Goormaghtigh cells and the epithelioid (or juxtaglomerular cells in the kidneys of desert rodents (Mongolian Gerbils) with those of the Wistar rats. The macula cells (Table 1), which in the Wistar rats are clearly distinct from the non specific epithelial cells of the distal convolution, show, in the desert rats, noticeable fluctuations. Their enzyme histochemical reactions are often weaker than those of the distal convolution cells, with the exception of the NAD-tetrazolium-reductase activity. The Goormaghtigh cells (Table 2) in the kidneys of the Meriones have a much larger enzymatic spectrum than in the Wistar rats. Here also, we find functional variations in the examined desert species. In the epithelioid cells (Table 3) we observed a somewhat weaker enzymatic activity in the Meriones. These cells contain no secretion granules, this making their diagnosis difficult.
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PMID:Comparison of the activities of some dehydrogenases in the juxtaglomerular complex of kidneys of Wistar rats and desert rats (Meriones unguiculati). 2 Nov 52

NADP-linked malic enzyme [EC 1.1.1.40] was highly purified from Escherichia coli W cells. The purified enzyme was homogeneous as judged by ultracentrifugation and gel electrophoresis. The apparent molecular weights obtained by sedimentation equilibrium analysis, from diffusion and sedimentation constants, and by disc electrophoresis at various gel concentrations were 471,000, 438,000, and 495,000, respectively. The subunit molecular weights obtained by sedimentation equilibrium analysis in the presence of 6 M guanidine hydrochloride and gel electrophoresis in the presence of sodium dodecyl sulfate were 76,000 and 82,000, respectively. The sedimentation coefficient (S(0)20, W) was 13.8S, and the molecular activity was 44,700 min-1 at 30 degrees C. The amino acid composition of the enzyme was determined, and the results were compared with those of NAD-linked malic enzyme from the same organism and those of pigeon liver NADP-linked malic enzyme. The partial specific volume was calculated to be 0.738 ml/g. The Km value for L-malate was 2.3 mM at pH 7.4. Malonate, tartronate, glutarate, and DL-tartrate competitively inhibited the activity. The saturation profile for L-malate exhibited a marked cooperativity in the presence of both chloride ions and acetyl-CoA. However, acetyl-CoA alone did not show cooperativity or produce inhibition in the absence of chloride ions. Vmax and Km were determined as a function of pH. The optimum pH for the reaction was 7.8. Inspection of the Dixon plots suggested that three ionizable groups of the enzyme are essential for the enzyme activity. In addition to the oxidative decarboxylase activity, the enzyme preparation exhibited divalent metal ion-dependent oxaloacetate decarboxylase and alpha-keto acid reductase activities. Based on the above results, the molecular properties of the enzymatic reaction are discussed.
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PMID:Studies on regulatory functions of malic enzymes. VI. Purification and molecular properties of NADP-linked malic enzyme from Escherichia coli W. 3 76

A highly active preparation of diacetyl(acetoin) reductase was isolated from cell-free extracts of the yeast Saccharomyces vini. Since the activity ratio of 2,3-butanediol dehydrogenase and diacetyl(acetoin) reductase was practically unchanged in the process of 65-fold purification, it can be assumed that the yeast cells contain one enzyme, which catalyzes both the reversible oxidation of 2,3-butanediol to acetoin by NAD and the practically irreversible reduction of diacetyl to acetoin by NAD-H2. Some properties of this enzyme were studied.
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PMID:Isolation, purification, and study of certain properties of diacetyl(acetoin) reductase in the yeast Saccharomyces vini. 4 79

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

Serial sections of longissimus dorsi and rectus femoris muscles from 15 Yorkshire breed pigs (live weights 24-46 and 49-139 kg) were stained for glycogen (PAS) and a mitochondrial enzyme (NAD tetrazolium reductase). Muscle fibres with a low mitochondrial content in both muscles were more frequently PAS-positive than fibres with a high or intermediate mitochondrial content. However, some pigs had all their muscle fibres PAS-positive while one pig with a high post-mortem muscle pH had all rectus femoris fibres PAS-negative. Relative to lighter weight pigs, longissimus dorsi muscles of heavy pigs tended to have less fibres with a high mitochondrial content and less fibres with a positive PAS reaction. Compared to longissimus dorsi muscles, rectus femoris muscles had more fibres with a high mitochondrial content and less with a positive PAS reaction. All fibres in both muscles became PAS-negative with an accompanying decrease in pH by 24 hr post-mortem. Fibres from longissimus dorsi muscles frequently had PAS-positive sarcoplasmic cores between their myofibrils. Heavy pigs tended to have larger cores (up to a mean maximum diameter of 13.4 mum), more fibres with cores, and more cores per fibre. The pigs involved exhibited no other ante- or post-mortem muscle abnormalities.
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PMID:Relationships between mitochondrial content and glycogen distribution in porcine muscle fibres. 5 44


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