Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.6.99.5 (NADH dehydrogenase)
2,135 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oxidation of exogenous NADH in mitochondria isolated from wild type and mi-1 mutant of Neurospora crassa decreases rapidly in vitro. In mi-1 mutant mitochondria the inactivation concerns the alternate pathway of oxidation whereas in the wild type it involves an unknown component of the respiratory chain. The activity of the primary NADH dehydrogenase is constant within the time of the experiments (2-4 h). NADH oxidase is not inactivated if oxygen is removed from the incubation medium by nitrogen bubbling. Succinate oxidase does not show any remarkable changes in activity within 2-3 h. In fresh mitochondria of the mi-1 mutant reduced ubiquinone is completely reoxidized by cytochrome oxidase but only 80% reoxidized by the alternate oxidase. In aged mitochondria of the mi-1 mutant in the presence of cyanide, ubiquinone is reduced to the level characteristic for fresh mitochondria in which respiration is completely inhibited by cyanide plus salicylhydroxamic acid. In these mitochondria the reoxidation of the reduced ubiquinone proceeds only via the cytochrome pathway. It is supposed that a labile component(s) of the respiratory chain present in the mi-1 mutant and the wild type mitochondria may, in mi-1 mutant, act as an alternate oxidase.
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PMID:Disappearance of the cyanide-insensitive pathway of oxidation in mitochondria of MI-1 mutant of Neurospora crassa in vitro. 20 34

Recent studies have shown that intrarectal administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS) in ethanol or intramural injection of TNBS in saline produces an acute and possibly chronic colitis in rats. It has been assumed that interstitial TNBS initiates the inflammatory response via macrophage-mediated recognition and degradation of TNBS-modified mucosal cells and proteins. However, it is known that certain flavoproteins and/or reductants interact with compounds containing the nitro functional group to generate pro-inflammatory, nitrogen-centered free radicals and reactive oxygen metabolites. The objective of this study was to assess the ability of the rat colon, using either colon homogenates, isolated colonocytes, or intestinal interstitial fluid, to produce reactive oxygen species via enzymatic and/or nonenzymatic metabolism of TNBS. It was found that the addition of TNBS (1 mmol/L) to the 10,000 x g supernatant of rat colon homogenates increased the rate of superoxide production from normally undetectable levels to 2.6 +/- 0.23 nmol.min-1.mg protein-1. Addition of nicotinamide adenine dinucleotide, reduced form (NADH; 1 mmol/L) to colon homogenates containing TNBS significantly enhanced superoxide production to 10.4 +/- 0.9 nmol.min-1.mg-1. Similarly, addition of nicotinamide adenine dinucleotide phosphate, reduced form (NADPH; 1 mmol/L) to colon extracts containing TNBS produced an even further increase in the rate of superoxide formation to 25.2 +/- 1.1 nmol.min-1.mg-1. Addition of NADH or NADPH to the colon homogenate in the absence of TNBS produced no detectable superoxide formation, suggesting that TNBS was required for the enhanced oxidative metabolism. In a separate series of experiments, it was found that isolated colonocytes produced small but significant amounts of superoxide (3.15 +/- 0.6 nmol/2 x 10(6) cells) that were significantly increased in the presence of ethanol to 6.55 +/- 1.14 nmol/2 x 10(6) cells. Using purified preparations of two flavoproteins found in the rat colon, it was shown that the addition of TNBS (1 mmol/L) to purified NADH dehydrogenase or glutathione reductase increased the rate of superoxide formation by these enzymes from normally undetectable levels to 1.6 nmol/min and 1.2 nmol/min, respectively. In addition, it was found that intestinal interstitial fluid (lymph) initiated redox cycling of TNBS such that 28.1 +/- 1.6 nmol of oxygen was consumed per minute per milliliter of lymph. This increase in oxygen consumption was inhibited by the addition of superoxide dismutase and catalase. One possible metabolite involved in both mucosal and lymph-mediated metabolism of TNBS is ascorbic acid.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Metabolism of trinitrobenzene sulfonic acid by the rat colon produces reactive oxygen species. 164 28

The respiration chain in the membranes of whole Actinomyces roseoflavus (var. roseofungini) cells from the parent and secondary cultures is sensitive to KCN, non-sensitive to Triton X-100 treatment removing the antibiotic roseofungin from the cells, and has a very high for the bacteria respiration control. When the cells are in contact with atomic tritium at the temperature of liquid nitrogen, roseofungin is tritiated and binds to A. roseoflavus isolated membranes and whole cells, mostly to those of the parent culture as compared to the secondary culture. A fraction of membranes which lost NADH dehydrogenase in the course++ of purification was isolated from the cells disintegrated in the frozen state.
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PMID:[Comparative study of different variants of Actinomyces roseoflavus producing the polyene antibiotic roseofungin]. 321 Oct 8

Pd(II) complexes of two anthracyclines, adriamycin and daunorubicin, have been studied. Using potentiometric absorption, fluorescence, and circular dichroism measurements, we have shown that adriamycin can form two complexes with Pd(II). The first complex (I) involves two molecules of drug per Pd(II) ion; one of the molecules is chelated to Pd(II) through the carbonyl oxygen on C12 and the phenolate oxygen on C11, and the other one is bound to Pd(II) through the nitrogen of the amino sugar. This complexation induces a stacking of the two molecules of drug. In the second complex (II), two Pd(II) ions are bound to two molecules of drug (A1 and A2). One Pd(II) is bound to the oxygen on the carbons C11 and C12 of molecule A1 and the amino sugar of molecule A2 whereas the second Pd(II) ion is bound to the oxygen on C11 and C12 of molecule A2 and the amino sugar of molecule A1. The same complexes are formed between Pd(II) and daunorubicin. The stability constant for complex II is beta = (1.3 +/- 0.5) X 10(22). Interaction with DNA has been studied, showing that almost no modification of the complex occurred. This complex displays antitumor activity against P-388 leukemia that compares with that of the free drug. Complex II, unlike adriamycin, does not catalyze the flow of electrons from NADH to molecular oxygen through NADH dehydrogenase.
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PMID:Metal anthracycline complexes as a new class of anthracycline derivatives. Pd(II)-adriamycin and Pd(II)-daunorubicin complexes: physicochemical characteristics and antitumor activity. 396 54

1. Plasma membranes were isolated from Krebs II ascite cells grown in the mouse. Cells were disrupted by nitrogen cavitation in an isotonic alkaline buffer containing magnesium and ATP. Isolation was performed in an alkaline-buffered self-generating gradient of Percoll with an angular rotor. At each step of the preparation, the pH appeared as the critical aspect of our procedure. 2. External membrane markers were concanavalin A and 5'-nucleotidase (EC 3.1.3.5). They reached a relative specific activity of 10, whereas this value was only of 0.7 for the endoplasmic reticulum marker, NADH dehydrogenase (EC 1.6.99.3). 3. Plasma membrane from 4 ml packed cells were isolated within 1 h after homogenization with good yield: 50% and 67% of total [3H]concanavalin A and 5'-nucleotidase, respectively, were recovered in the two plasma membrane fractions. 4. Electron microscopy examination showed the presence of vesicles of different sizes devoid of other structural contaminants. 5. Using the specific binding of concanavalin A to the external cell membrane, it was calculated that about 50% of the total cell phospholipid and 10% protein are located in the plasma membrane. Their sphingomyelin content is much higher than in the whole cell, in contrast to phosphatidylinositol, known as a more specific endoplasmic reticulum phospholipid.
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PMID:Isolation and characterization of plasma membranes from krebs II ascite cells using Percoll gradient. 628 35

The genes that encode the two different subunits of the novel electron-transferring flavoprotein (ETF) from Megasphaera elsdenii were identified by screening a partial genomic DNA library with a probe that was generated by amplification of genomic sequences using the polymerase chain reaction. The cloned genes are arranged in tandem with the coding sequence for the beta-subunit in the position 5' to the alpha-subunit coding sequence. Amino acid sequence analysis of the two subunits revealed that there are two possible dinucleotide-binding sites on the alpha-subunit and one on the beta-subunit. Comparison of M. elsdenii ETF amino acid sequence to other ETFs and ETF-like proteins indicates that while homology occurs with the mitochondrial ETF and bacterial ETFs, the greatest similarity is with the putative ETFs from clostridia and with fixAB gene products from nitrogen-fixing bacteria. The recombinant ETF was isolated from extracts of Escherichia coli. It is a heterodimer with subunits identical in size to the native protein. The isolated enzyme contains approximately 1 mol of FAD, but like the native protein it binds additional flavin to give a total of about 2 mol of FAD/dimer. It serves as an electron donor to butyryl-CoA dehydrogenase, and it also has NADH dehydrogenase activity.
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PMID:Cloning and analysis of the genes for a novel electron-transferring flavoprotein from Megasphaera elsdenii. Expression and characterization of the recombinant protein. 969 53

The participation of oxidative mechanisms in major histocompatibility complex (MHC) class II-restricted antigen presentation was studied in vitro. In general, antigen processing is inhibited when peritoneal macrophages (MO) are incubated with scavengers of reactive oxygen intermediates (ROI): mannitol (an.OH scavenger), dimethylurea (DMTU, which reacts with H2O2 and HOCl) and NCO-700 (an epoxysuccinic acid derivative which inhibits oxidant production by activated phagocytes and can scavenge reactive oxygen species in both NaOCl and hypoxanthine (XOD) systems). However, neither rotenone and antimycins (inhibitors of O-2 production at the NADH dehydrogenase and ubiquinone-cytochrome b regions, respectively) nor aminoguanidine (an inducible nitric oxide synthase inhibitor) impaired antigen presentation, thus indirectly discarding the participation of mitochondrial oxidation and reactive nitrogen intermediates (RNI) in antigen processing. ROI scavengers do not inhibit the MHC class II-restricted presentation of antigens that need processing but have their disulphide bonds reduced. It can be shown that oxidation of protein antigens (either by chlorination or performic acid treatment) allow protein unfolding and enhance both processing and exposure of immunogenic epitopes to specific T cells.
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PMID:Oxidation of defined antigens allows protein unfolding and increases both proteolytic processing and exposes peptide epitopes which are recognized by specific T cells. 982 92

Some sterically hindered N-substituted derivatives of daunorubicin are known to be poor substrates for NADH dehydrogenase, NADPH cytochrome P450 reductase and xanthine oxidase. In consequence, poor oxygen radical generation by these compounds is observed. In this study we examined a new family of sugar-N-substituted derivatives of daunorubicin bearing a bulky substituent introduced on the nitrogen atom through the amidine spacer. These compounds were found to be very active in radical formation catalyzed by all three studied enzymes. Thus, the introduction of a heterocyclic ring, even if it is bulky but flexible, on the nitrogen atom of daunosamine moiety through the one-atom spacer (amidine group), does not induce the steric hindrance effect on the interaction of daunorubicin derivatives with these flavoprotein enzymes.
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PMID:The ability of new formamidine sugar-modified derivatives of daunorubicin to stimulate free radical formation in three enzymatic systems: NADH dehydrogenase, NADPH cytochrome P450 reductase and xanthine oxidase. 1096 87

Cytosolic redox balance has to be maintained in order to allow an enduring cellular metabolism. In other words, NADH generated in the cytosol has to be re-oxidized back to NAD(+). Aerobically this can be done by respiratory oxidation of cytosolic NADH. However, NADH is unable to cross the mitochondrial inner membrane and mechanisms are required for conveying cytosolic NADH to the mitochondrial electron transport chain. At least two such systems have proved to be functional in S. cerevisiae, the external NADH dehydrogenase (Luttik et al., 1998; Small and McAlister-Henn, 1998) and the G3P shuttle (Larsson et al., 1998). The aim of this investigation was to study the regulation and performance of these two systems in a wild-type strain of S. cerevisiae using aerobic glucose- and nitrogen-limited chemostat cultures. The rate of cytosolic NADH formation was calculated and as expected there was a continuous increase with increasing dilution rate. However, measurements of enzyme activities and respiratory activity on isolated mitochondria revealed a diminishing capacity at elevated dilution rates for both the external NADH dehydrogenase and the G3P shuttle. This suggests that adjustment of in vivo activities of these systems to proper levels is not achieved by changes in amount of protein but rather by, for example, activation/inhibition of existing enzymes. Adenine nucleotides are well-known allosteric regulators and both the external NADH and the G3P shuttle were sensitive to inhibition by ATP. The most severe inhibition was probably on the G3P shuttle, since one of its member proteins, Gpdp, turned out to be exceptionally sensitive to ATP. The external NADH dehydrogenase is suggested as the main system employed for oxidation of cytosolic NADH. The G3P shuttle is proposed to be of some importance at low growth rates and perhaps its real significance is only expressed during starvation conditions.
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PMID:Cytosolic redox metabolism in aerobic chemostat cultures of Saccharomyces cerevisiae. 1132 72

The alkaloids from Chelidonium majus L. which had a significant inhibitory effect in mitochondrial respiration were those which contain a positive charge due to a quaternary nitrogen atom, i.e., chelerythrine, sanguinarine, berberine and coptisine, both with malate+glutamate or with succinate as substrates. When malate+glutamate was used as substrate, chelerythrine and berberine, which contain methoxy groups, were particularly more active, since they had a strong effect even at low concentrations. In submitochondrial particles, berberine and coptisine had a marked inhibitory effect on NADH dehydrogenase activity but practically no effect on succinate dehydrogenase activity, whereas chelerythrine and sanguinarine inhibited more strongly succinate dehydrogenase than NADH dehydrogenase, which is in agreement with the results found for mitochondrial respiration. Protopine and allocryptopine, which did not inhibit mitochondrial respiration, strongly inhibited NADH dehydrogenase in submitochondrial particles, but had no effect on succinate dehydrogenase activity.
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PMID:Inhibition of mouse liver respiration by Chelidonium majus isoquinoline alkaloids. 1461 66


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