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)

Female rats were injected subcutaneously with ethionine, and enzymic activities of liver membranes (Na+-k+-stimulated ATPase, Mg2+-stimulated ATPase, glucose-6-phosphatase, NADPH: cytochrome c oxido-reductase and NAD-nucleosidase) examined at proper intervals, during the intraperitoneal treatment of an egg phospholipid preparation (EPL). It is shown that EPL is unable to overcome the enzymic changes due to severe ethionine treatment, but is able to facilitate the recovery times after drug withdrawal for all the enzymic activities, except for NAD-nucleosidase. At lower dosage of the drug, the ethionine treatment is able to prevent the observed change of the glucose-6-phosphatase activity but not that of the Mg2+-ATPase. It is suggested that the EPL treatment may modify the chemical composition ahd/or architecture of liver membranes, altered by the ethionine injection, thus acting, at least partially, on the enzymic changes.
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PMID:The effect of egg phospholipid administration upon liver enzymic activities during ethionine treatment. 18 Dec 70

The reaction of cytochrome c with ethyl thioltrifluoroacetate was carried out under conditions which led to the selective trifluoroacetylation of a small number of the 19 lysines. The mixture of derivatives was separated by ion-exchange chromatography and four different derivatives with well-resolved 19F nuclear magnetic resonance (NMR) spectra were obtained. Peptide mapping techniques indicated that one of these derivatives contained a single trifluoroacetyl group at lysine 22, and another derivative was singly labeled at lysine 25. The trifluoroacetylated lysine 22 derivative was fully active toward both succinate-cytochrome c reductase (EC 1.3.99.1) and cytochrome oxidase (EC 1.9.3.1) white the trifluoroacetylated lysine 25 derivative was fully active toward the reductase, but had a threefold greater Michaelis constant in the cytochrome oxidase reactin. This supports the hypothesis that the cytochrome oxidase binding site is located in the heme cervice region, and that Lys-25 is important in the binding. 19FNMR spectra of the cytochrome c derivatives bound to phospholipid vesicles were obtained. The reasonably narrow line widths (35-65 Hz) and good sensitivity of the trifluoroacetyl resonances indicated that they might be useful probes for the interaction of cytochrome c with intact mitochondria.
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PMID:An enzyme kinetics and 19F nuclear magnetic resonance study of selectively trifluoroacetylated cytochrome c derivatives. 18 7

Cellular membranes were prepared from the non-extending part of dark grown hypocotyls of Phaseolus aureus. The relative effectiveness of continuous and discontinuous sucrose gradient centrifugation for the separation of membranes was investigated. Characteristic densities of membranes were determined by the localization of enzyme activities on continuous sucrose gradients: NADH-cytochrome c-reductase for endoplasmic reticulum, beta-1-3-glucan synthetase for plasma-membrane and IDPase for dictyosomes. The difficulties involved in the application of ATPase and IDPase as specific membrane markers are discussed. Negative staining of isolated fractions indicated that intact dictyosomes could be prepared from this tissue without the use of chemical fixatives in the homogenization medium. Extraction of isolated membranes showed that carbohydrate-binding proteins (lectins) were present both in an easily removable and in a more strongly bound form. In vivo incorporation of D-[U-14C]glucose and subsequent isolation and solubilization of the different membranes showed that sugar-containing polymers could be released without hydrolytic techniques and were present in the equivalent extracts that exhibited lectin activity. The possibility of lectin-polysaccharide complexes in endoplasmic reticulum and dictyosomes and their involvement in the synthesis and transport of secretory substances by the membranes is discussed.
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PMID:Characterization, enzymatic and lectin properties of isolated membranes from Phaseolus aureus. 18 22

A direct, sensitive and reliable photometric assay procedure for monitoring the activity of non-specific 4-methoxybenzoate O-demethylases of microorganisms is described. The assay is based on the O-demethylation of 3-nitro-4-methoxybenzoate to the yellow-coloured product 3-nitro-4-hydroxybenzoate. Using this assay and by monitoring the oxidation rate of reduced pyridine nucleotides, the kinetic properties of a purified, reconstituted enzyme system composed of 4-methoxybenzoate monooxygenase (O-demethylating) and a reductase from Pseudomonas putida have been investigated. It has been found that the KM value of the monoxygenase of this enzyme system towards different substrates (i.e. tight couplers, uncouplers and partial uncouplers) rises from the extremely low value of 0.07 muM for the tight couplers to about 55 muM for the uncouplers. The effect of possible inhibitors and metal ions on the reconstituted enzyme system was investigated. The inhibition pattern was almost identical to that found for the purified reductase, only batho-phenanthrolinedisulfonate showing a greater inhibition of the reconstituted enzyme system. The affinity of the reductase towards NADH was found to be approximately 200-fold greater than that towards NADPH. Futhermore, the affinity of this reductase to NADH depended on the nature of the electron acceptor. The affinity to NADH was more than 10 times higher when the monooxygenase-substrate complex was used as the electron acceptor, than when cytochrome c or 2,6-dichloroindophenol was used. These differences are discussed on the basis of enzyme-enzyme interactions between the reductase and the monooxygenase.
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PMID:Kinetic studies on a 4-methoxybenzoate O-demethylase from Pseudomonas putida. 18 54

Cytochrome c immobilized on cyanogen bromide-activated Sepharose 4B may be used to study photochemical reactions in chloroplasts. Chloroplast reduction of both immobilized and soluble forms of the cytochrome occurs along the exogenous and endogenous pathways which results in a weaker reduction of the immobilized protein as compared to that of the soluble one. The time of the reduced immobilized cytochrome c oxidation in the dark is two orders of magnitude greater than that of the soluble one. This fact may be interpreted in terms of spatial dissociation of reductase and oxidase centers of chloroplasts with reference to the cytochrome. The optimal ionic strength for cytochrome reduction, i.e. ionic strength causing an in vitro destruction of the ferredoxin-NADP-reductase complex was found to equal to 0.2 M.
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PMID:[Cytochrome c immobilized on Sepharose 4B and its participation in photochemical reactions of chloroplasts]. 19 41

Although the preparation of rat liver Golgi apparatus isolated by our method contains appreciable activities of NADH- and NADPH-cytochrome c reductases and glucose-6-phosphatase, these enzymes as well as thiamine pyrophosphatase of the extensively fragmented Golgi fraction are partitioned in aqueous polymer two-phase systems quite differently from those associated with microsomes. Similarly, the partition patterns of acid phosphatase and 5'-nucleotidase of the Golgi fragments differ from those of homogenized lysosomes and plasma membrane, respectively. It is concluded that most, if not all, of these marker enzymes in the Golgi fraction cannot be ascribed to contamination by the non-Golgi organelles. In sucrose density gradient centrifugation the NADH- and NADPH-cytochrome c reductase activities of the Golgi fraction behave identically with galactosyltransferase but differently from the reductase activities of microsomes, again indicating that the reductases are inherently associated with the Golgi apparatus. NADPH-cytochrome c reductase of the Golgi preparation is immunologically identical with that of microsomes. The marker enzymes mentioned above and galactosyltransferase behave differently from one another when the Golgi fragments are subjected to partitioning in aqueous polymer two-phase systems, suggesting that these enzymes are not uniformly distributed in the Golgi apparatus structure.
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PMID:Biochemical studies on rat liver Golgi apparatus. II. Further characterization of isolated Golgi fraction. 20 81

Activity of aryl hydrocarbon hydroxylase (AHH), cytochrome c-reductase, and NADPH oxidase, and epinephrine oxidation to adrenochrome were determined in lung microsomes from intact, adrenalectomized, and adrenalectomized cortisol-treated female rats under ambient and hyperoxic conditions. Microsomal adrenochrome formation, which is initiated by superoxide anion or other free radicals, was increased by adrenalectomy and decreased by cortisol treatment. Exposure of animals to 100% oxygen caused a further increase in adrenochrome formation. NADPH-cytochrome c-reductase and AHH activities were increased in incubations of microsomes from animals which had received cortisol in vivo while adrenalectomy led to decreases activity. NADPH oxidase activity was increased by cortisol in lung microsomes in the presence of either epinephrine or cytochrome c. Epinephrine conversion to adrenochrome in the presence of lung microsomes was blocked by SOD, but NADPH-cytrochrome c-reductase and AHH activity were unaffected.
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PMID:An effect of corticosteroids and 100% oxygen on aryl hydrocarbon hydroxylase, cytochrome-c reductase, and free radical formation by rat lung microsomes. 21 Mar 49

NADPH cytochrome c (cyt c) reductase and glucose-6-phosphatase, two enzymes thought to be restricted to the endoplasmic reticulum (ER) and widely used as ER markers, are present in isolated Golgi fractions assayed immediately after their isolation. Both enzymes are rapidly inactivated in fractions stored at 0 degrees C in 0.25 M sucrose, conditions which do not affect the activity of other enzymes in the same preparation. The inactivation process was shown to be dependent on time and protein concentration and could be prevented by EDTA and catalase. Morphological evidence shows that extensive membrane damage occurs parallel with the inactivation. Taken together with the immunological data in the companion paper, the findings indicate that the enzymes NADPH cyt c reductase and probably glucose-6-phosphate are indigenous components of Golgi membranes.
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PMID:Endoplasmic reticulum marker enzymes in Golgi fractions--what does this mean? 21 50

An assay has been developed to study the steady-state kinetics of the reduction of cytochrome c by purified beef heart mitochondrial cytochrome c reductase (cytochrome bc(1) complex, complex III). An analogue of coenzyme Q(2) (2,3-dimethoxy-5-methyl-6-decylhydroquinone) was employed as an antimycin-sensitive reductant. The kinetics of reaction of ten different mono(4-carboxy-2,6-dinitrophenyl) derivatives of horse cytochrome c were determined. The modified proteins showed higher apparent K(m) values than the native protein and greater sensitivity to ionic strength, defining an interaction domain on cytochrome c for purified cytochrome c reductase. This interaction site is located on the front surface of the molecule (which contains the exposed heme edge) and surrounds the point at which the positive end of the dipole axis crosses the surface of the protein. The site is similar to that previously determined for mitochondrial cytochrome c oxidase and yeast cytochrome c peroxidase, suggesting that the primary interaction with redox partners is directed by the dipolar charge distribution on cytochrome c. The extensive overlapping of the interaction domains for the mitochondrial cytochrome c oxidase and reductase indicates that cytochrome c must be mobile in order to transfer electrons between them, depending on their relative positions in the membrane. Whether such mobility is necessary in intact mitochondria depends on whether the interactions with the complete membrane-bound system are the same as with the purified components.
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PMID:Definition of cytochrome c binding domains by chemical modification: kinetics of reaction with beef mitochondrial reductase and functional organization of the respiratory chain. 21 93

The binding of rat liver cytochrome c oxidase to phenyl-Sepharose and various alkyl and omega-aminoalkyl agarose gels has been studied. Deoxycholate-solubilized cytochrome c oxidase was tightly bound to hexyl, octyl, omega-aminohexyl, omega-aminooctyl agarose as well as to phenyl-Sepharose. This hydrophobic interaction was used for the purification of cytochrome c oxidase. The enzyme which was eluted from phenyl-Sepharose was devoid of NADH (NADPH)-acceptor reductase activities. The heme a content was 15.4 nmol per mg of protein. The purified enzyme was resolved into seven polypeptides upon polyacrylamide gel electrophoresis in sodium dodecylsulfate with molecular weights of 40,000, 23,200, 21,500, 14,500, 12,600, 8900, and 4900. Antibodies raised in rabbits against the pure enzyme did not cross-react with cytochrome c oxidases from either beef heart or yeast mitochondria. Cytochrome c oxidase bound to octyl-Sepharose or phenyl-Sepharose exhibited a very low catalytic activity. The possible modes of interaction of cytochrome c oxidase with the hydrophobic ligands are discussed.
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PMID:Hydrophobic interactions of cytochrome c oxidase. Application to the purification of the enzyme from rat liver mitochondria. 22 47


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