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)

A water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, has been used to cross-link horse heart cytochrome c to spinach chloroplast plastocyanin. The complex was formed in yields up to 90% and was found to have a stoichiometry of 1 mol plastocyanin per mol cytochrome c. The cytochrome c in the complex was fully reducible by ascorbate and potassium ferrocyanide, and had a redox potential only 25 mV less than that of native cytochrome c. The complex was nearly completely inactive towards succinate-cytochrome c reductase and cytochrome c oxidase, suggesting that the heme crevice region of cytochrome c was blocked. We propose that the carbodiimide promoted the formation of amide cross-links between lysine amino groups surrounding the heme crevice of cytochrome c and complementary carboxyl groups on plastocyanin. It is of interest that the high-affinity site for cytochrome c binding on bovine heart cytochrome c oxidase has recently been found to involve a sequence of subunit II with some homology to the copper-binding sequence of plastocyanin.
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PMID:The use of a water-soluble carbodiimide to cross-link cytochrome c to plastocyanin. 630 54

The effect of sodium selenite administered acutely or repeatedly on the biochemical components of the hepatic microsomal monooxygenase enzyme system was examined in male rats. 72 h following acute administration of selenium (2.4 mg Se/kg, i.p.), there was a significant decrease in ethylmorphine-N-demethylase activity and cytochrome P-450 levels but no change in aniline hydroxylase or NADPH cytochrome c reductase activity. Following repeated administration of selenite in the drinking water (1, 2, or 4 ppm Se) for 30 days, there was no alteration in any of the parameters measured. Following the in vitro additions of selenite to microsomes obtained from untreated rats, ethylmorphine-N-demethylase and aniline hydroxylase activities were inhibited at selenium concentrations of 10(-4) M or greater, but the inhibition achieved was less than 50%. No alterations in cytochrome P-450 levels were observed. These results indicate that selenium is a rather weak, indirect, and substrate-specific inhibitor of the hepatic monooxygenase enzyme system.
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PMID:Effect of acute and repeated selenium treatment on hepatic monooxygenase enzyme activity in male rats. 641 10

The effect of intragastric ethanol, 7.8 g/kg, on the microsomal enzyme activities NADPH cytochrome c reductase, aminopyrine N-demethylase and aniline hydroxylase, were investigated in two sizes (150 g and 260 g) of mature male rats having free access to food and water for the 23 hours following ethanol administration. Controls received intragastric water and were given free access to food and water (fed controls) or only water (fasted controls). The ethanol group had a significantly lower food intake than the fed control group, and food intake in the large rats was more decreased by ethanol than that of the small rats, corresponding to slower recovery from intoxication. Ethanol and fasting increased aniline hydroxylation and decreased acetone enhancement of aniline hydroxylation to the same degree, whereas only fasting caused a significant decrease in aminopyrine N-demethylation. Some of the effects of acute ethanol intoxication on hepatic microsomal enzyme activities appear to be mediated via decreased food intake.
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PMID:Acute ethanol intoxication decreases subsequent food intake and changes hepatic microsomal enzyme activities similarly to fasting. 668 9

The water-soluble carbodiimide, N-ethyl-3-(3-dimethylaminopropyl)carbodiimide was found to effectively cross-link ferredoxin to ferredoxin-NADP+ reductase. The covalent complex has a stoichiometry of 1 mol of ferredoxin per mol of the reductase. The flavoprotein moiety of the cross-linked complex maintains most of its diaphorase activity and more interestingly has gained the capacity to catalyze the NADPH-cytochrome c reaction without addition of free ferredoxin in the assay mixture. Furthermore, the cross-linked complex binds NADP+ with a Kd = 88 microM at an ionic strength of 0.02 M. These results show that a ternary complex among the reductase and its substrates can be formed, suggesting that the binding sites for ferredoxin and the pyridine nucleotides are distinct. The bound ferredoxin can interact with cytochrome c; the iron-sulfur cluster of the cross-linked complex is shown to be reduced under anaerobic conditions by NADPH and to be required for the catalysis of the NADPH-cytochrome c reductase reaction. The cross-linked complex, added to thylakoids inhibited by the antibody against the reductase, catalyzes the H2O-cytochrome c photoreduction, which suggests that the ferredoxin moiety of the complex can interact with its electron donor in the photosynthetic chain. Restoration of NADP+ photoreduction requires the addition of free ferredoxin.
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PMID:A cross-linked complex between ferredoxin and ferredoxin-NADP+ reductase. 672 48

The hepatic microsomal cytochromes P-450 and b5, as well as the enzymes of the hepatic microsomal electron-transport system (HMETS), including NADPH oxidase and NAPDH cytochrome c reductase, were monitored in male ICR mice (25 - 30 g) over a six-day period following repeated oral administration of methadone hydrochloride 12.5, 25, or 50 mg/kg per day, or an equivalent volume of water. Cytochrome P-450 content, when expressed per milligram of microsomal protein, was elevated as early as day 1 of administration. This increase in cytochrome P-450, which lasted throughout the period of administration, appeared to correlate with the previously reported increase in the hepatic microsomal enzyme methadone N-demethylase and tolerance to methadone lethality. The activities of the enzymes NADPH cytochrome c reductase and NADPH oxidase were both elevated significantly by day 2 of administration. However, these increases returned to control levels by day 6 of treatment. The only other cytochrome in the HMETS, cytochrome b5, showed no significant change following repeated oral methadone administration. Further, methadone administration depressed the hepatic microsomal protein content following two days of treatment and no elevation above control values was noted. The significance of these findings with respect to the role of the HMETS in the development of tolerance is discussed in some detail for methadone, as well as the findings previously reported by this laboratory for its acetylated congener, l-alpha-acetylmethadol.
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PMID:The role of the hepatic microsomal electron-transport system in the development of metabolic tolerance from repeated oral methadone administration in mice. 676 37

The influence of dietary cholesterol on drug metabolism was studied by feeding rats either a cholesterol-free or a high (2%) cholesterol diet for 4 weeks from weanling onward and giving phenobarbitone (Pb) and/or carbon tetrachloride (CCl4) thereafter. Pb was given in drinking water for 7 days at a dosage of 100 mg/kg and CCl4, at a dosage of 1.5 mg/kg SC 6 days before assays of drug-metabolizing enzymes. The cytochrome P-450 concentration was 2-fold in rats fed the 2% cholesterol diet in comparison with those fed the cholesterol-free diet. Only a weak induction by Pb was found in the cholesterol-free group. Only slight differences due to the cholesterol diets or due to the administration of xenobiotics were found in the NADPH cytochrome c reductase activity. The PPO hydroxylase activity was 2-fold in the livers of rats fed the 2% cholesterol diet in comparison with those fed the cholesterol-free diet. In the ethoxyresorufin deethylase activity, differences between diets were present first after the administration of xenobiotics. No change in the hepatic aryl hydrocarbon hydroxylase activity was found due to changes in the cholesterol content of the diets. The ethoxycoumarin O-deethylase activity was 2-fold in the livers of rats fed 2% cholesterol diet from those fed the cholesterol-free diet. The inducibility of ethoxycoumarin O-deethylase was equal, regardless of which diet was used. The hepatic epoxide hydrolase activity of rats fed 2% cholesterol was 3-fold in comparison with the cholesterol-free group. The inducibility by Pb was higher in the livers of the cholesterol-free (3.3-fold) than 2% cholesterol-fed rats (2.4-fold). The hepatic UDP-glucuronosyl-transferase activity was 1.5-fold in 2% cholesterol-fed rats in comparison with rats fed the cholesterol-free diet. The inducibility by CCL4 was found only in rats fed the cholesterol-free diet. The results suggest that dietary cholesterol modifies the enzyme activities in the liver and modifies their response to enzyme inducers.
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PMID:Dietary cholesterol-induced changes of xenobiotic metabolism in liver. II. Effects of phenobarbitone and carbon tetrachloride on activities of drug-metabolizing enzymes. 682 90

The NADH-dehydrogenase isolated from the M. lysodeikticus membranes was reconstituted into liposomes from the lipids obtained from the same membranes. The presence and degree of the reconstitution were investigated by two-dimensional immunoelectrophoresis and photoreactive hydrophobic label. The quenching of protein fluorescence by the aqueous quencher J- was practically the same for the enzyme in the reconstituted system and in the detergent solution, whereas the quencher interacting with the membrane--cetylpyridinium chloride--was effective in the first case and not effective in the second one. Evidence for the energy transfer from protein chromophores of NADH dehydrogenase in the proteoliposomes (lambda excit = 286 nm) to the hydrophobic fluorescent probe pyrene was obtained. It was found that about 30% of the chromophores in the enzyme molecule are involved in this process. The hydrophobic spin probe, whose paramagnetic fragment is located on the surface and not inside the hydrophobic phase of the membrane, can act as electron acceptor during NADH oxidation in the reconstituted system. The data obtained are suggestive of the exposure of the bulk of the enzyme molecule to the environment and of interaction of the smaller part of the molecule with the lipid phase. The active center is located on the part of the enzyme molecule which is exposed to water. It is assumed that the NADH-dehydrogenase molecule is exposed to water. It is assumed that the NADH-dehydrogenase molecule is involved in heat diffusion which facilitates the active center interaction with the membrane surface.
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PMID:[Interaction of NADH-dehydrogenase from M. lysodeikticus membranes with lipids in a reconstituted system]. 707 74

The subcellular distribution of rat erythrocyte NADH-cytochrome b5 reductase was determined by radioimmunoassay, using a rabbit antibody against the cathepsin D cleaved water-soluble fragment of rat liver microsomal reductase (I-reductase), which is known to be immunologically similar to the red cell enzyme. Erythrocytes contained approximately 30 ng of reductase/mg of protein, of which 90% were recovered in the hemolysate supernatant and 2.3% in the ghost fraction. After concentration by precipitation with 70% saturated (NH4)2SO4, the NADH-cytochrome c reductase activity of the soluble enzyme could be assayed in the presence of cytochrome b5, and was found to be inhibited by anti 1-reductase antibodies. The sodium dodecyl sulfate-polyacrylamide gel electrophoretic mobilities of erythrocyte membrane-associated and soluble reductase of the liver microsomal enzyme and its cathepsin D cleaved hydrophilic fragment (I-reductase) were examined in crude fractions by blotting followed by specific and highly sensitive immunostaining. The intact microsomal enzyme and the two erythrocyte reductases all had similar mobilities and migrated behind 1-reductase. However, the ghost-associated reductase, which was not attributable to contaminating leukocyte or reticulocyte membranes, was distinguishable from the soluble form by two criteria: (i) a lower dependence on exogenous cytochrome b5 in the NADH-cytochrome c reductase assay; and (ii) a larger apparent Mr upon gel filtration in the presence of Triton X-100, presumably because of detergent binding. Considering these results, possible biogenetic relations between membrane-bound and soluble erythrocyte reductase are discussed.
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PMID:Rat erythrocyte NADH-cytochrome b5 reductase. Quantitation and comparison between the membrane-bound and soluble forms using an antibody against the rat liver enzyme. 714 81

Two different nutritionally adequate liquid diets containing either 18% protein, 47% carbohydrate and 35% lipid, or 18% protein, 12% carbohydrate and 70% lipid were given to rats once daily or in four divided doses for 3 weeks. The liquid diets decreased hepatic protein content and concentration and the activities of hepatic gamma-glutamyl transferase and NADPH cytochrome c reductase, compared to a zero time group fed chow and water. There were no important differences between the treatment groups. Aniline hydroxylase activity was also decreased by the liquid diets, but the high-lipid diet decreased the activity significantly less than the high-carbohydrate diet. Rats fed chow and water ad libitum for 3 weeks were less different from the zero time value than rats in any of the liquid diet groups. The effects of liquid diets may be important in alcohol research, where a high-carbohydrate liquid diet in restricted amounts is being widely used for feeding the control animals.
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PMID:Effects of four restricted liquid diet regimens and one nonrestricted solid diet regimen on enzyme activities associated with hepatic drug metabolism. 715 71

The main kinetic regularities of the NADH regeneration system functioning was studied. A theoretical interpretation of the dependence of the stationary reaction rate in a two-enzyme system with a common cofactor on the enzyme, cofactor and substrate concentrations and the catalytic parameters of individual enzymatic processes was obtained. A mathematical analysis of the dependences of the stationary rate on the content of each enzyme in the system at different activity ratios of each enzyme and within a broad range of initial cofactor concentrations was carried out. The kinetics of regeneration of native NADH and the NADH immobilized on a water-soluble 4-vinylpyridine and acroleine copolymer in a model two-enzyme formate dehydrogenase--NADH dehydrogenase system were investigated.
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PMID:[Kinetics of the NADH regenerating system using bacterial formate dehydrogenase]. 724 90


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