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)

The mycotoxin citrinin, depressed the phosphorylation efficiency of liver mitochondria as deduced from a decrease of respiratory coefficient and of the ADP/O ratio. Citrinin (1.0 mM) inhibited some enzymes linked to the respiratory chain, namely NADH oxidase and NADH cytochrome c reductase involved with complex I. The activities of enzymes related with other enzymatic complexes of the respiratory chain were either unaffected or enhanced. ATPase activity was inhibited by the mycotoxin. Malate, glutamate, and 2-oxoglutarate dehydrogenases were also inhibited. The transmembrane potential (delta psi), developed by energized mitochondria and depolarization on the addition of ADP, was decreased. The results suggest that citrinin promotes a partial dissipation of the transmembrane potential, different from that resulting from a classical uncoupler such as 2,4-dinitrophenol.
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PMID:Mechanism of citrinin-induced dysfunction of mitochondria. II. Effect on respiration, enzyme activities, and membrane potential of liver mitochondria. 133 Mar 54

Citrinin depresses the phosphorylation efficiency of rat renal cortical mitochondria, as inferred from the decrease of the respiratory control coefficient (RC) and ADP/O ratios. The transmembrane potential (delta psi) developed by energized mitochondria and the depolarization upon ADP addition are also decreased. Citrinin (1.0 mM) inhibits almost all enzymes linked to the respiratory chain and increases the activity of succinate cytochrome c reductase and succinate oxidase (coupled). Malate and glutamate dehydrogenases are also inhibited. The inhibitory action of citrinin on phosphorylation efficiency could be related to the following findings: the effect on complex I; the action on the ATP synthetase complex; the partial inhibition of the transmembrane potential.
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PMID:Mechanism of citrinin-induced dysfunction of mitochondria. I. Effects on respiration, enzyme activities and membrane potential of renal cortical mitochondria. 155 79

Growth of Mycobacterium phlei under low oxygen tension resulted in specific activities two to twenty times lower for formate dehydrogenase, malate dehydrogenase, beta-hydroxybutyrate dehydrogenase, lactate oxidase and NADH dehydrogenase than when cultures were grown under high aeration. An increase in fumarate reductase and succinate dehydrogenase occurred with M. phlei grown under low oxygen tension. Malate: vitamin K dehydrogenase and glucose-6-phosphate dehydrogenase activity were not significantly affected by the oxygen tension used to grow the bacteria, and neither culture contained a lactate dehydrogenase. With growth of M. phlei in conditions of low oxygen tension, cytochrome a was not detected, but cytochrome b was prominent in membranes and cytochrome c was present in the soluble fraction.
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PMID:Influence of oxygen tension on the respiratory activity of Mycobacterium phlei. 318 14

In Ascaris muscle mitochondria the major respiratory chain-linked phosphorylation activity is accomplished by a NADH-linked reduction of fumarate to succinate. Oxygen can also be employed as a terminal electron acceptor via a cyanide- and salicyl-hydroxamate-resistant terminal oxidase. As in fumarate-dependent electron transport this process appears to be coupled to energy conservation at phosphorylation site I. The branchpoint from which electrons are taken from the main respiratory chain to either the alternative oxidase or fumarate reductase is likely to be on the oxygen side of the NADH dehydrogenase segment. Malate and succinate are the only substrates which appreciably support respiration in the mitochondrion of the nematode. Regardless of the presence or absence of oxygen malate is utilized by an oxidation-reduction reaction resulting in the formation of pyruvate, acetate, succinate, propionate and CO2. In addition, aerobically, hydrogen peroxide is formed as the product of oxygen reduction. Succinate accumulation was found to be significantly higher in the anaerobic as compared to the aerobic incubation mixtures. This effect was accompanied by an increase in anaerobic malate consumption. ATP generation and the formation of pyruvate, acetate and propionate were found to be similar in the presence and absence of oxygen. In malate-supported respiration of intact Ascaris mitochondria reducing equivalents (NADH) are produced exclusively through pyruvate and acetate formation. These enzymatic reactions are functionally coupled to the electron transport-linked reductions of fumarate to succinate and oxygen to hydrogen peroxide, respectively. In accordance with the position of the redox potentials of the fumarate/succinate and O2/H2O2 couples, anaerobic and aerobic respiration was found to be associated with relatively low energy conservation efficiencies. Thus one molecule of ATP was conserved per 2e- transferred to fumarate or oxygen, respectively. No evidence could be obtained for a significant activity of energy conservation sites II and III and electron transfer through the alternative oxidase pathway was shown not to be coupled to phosphorylation.
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PMID:Mechanisms of respiration and phosphorylation in Ascaris muscle mitochondria. 744 10

Exogenous NADH oxidation by cauliflower (Brassica oleracea L.) bud mitochondria was sensitive to antimycin A and gave ADP/O ratios of 1.4 to 1.9. In intact mitochondria, NADH-cytochrome c reductase activity was only slightly inhibited by antimycin A. The antimycin-insensitive activity was associated with the outer membrane. Malate oxidation was sensitive to both rotenone and antimycin A and gave ADP/O values of 2.4 to 2.9. However in the presence of added NAD(+), malate oxidation displayed similar properties to exogenous NADH oxidation. In both the presence and absence of added NAD(+), malate oxidation was dependent on inorganic phosphate and inhibited by 2-n-butyl malonate.
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PMID:The oxidation of malate and exogenous reduced nicotinamide adenine dinucleotide by isolated plant mitochondria. 1665 36

Seedlings of castor bean (Ricinus communis cv. Hale) were exposed to a range of concentrations of gibberellin A(3) (GA(3)). Treatments for 20 hours with GA(3) concentrations of 0.5 muM or higher resulted in increased levels of NADH-cytochrome c reductase, phosphorylcholine glyceride transferase, and malate synthase in endoplasmic reticulum (ER) isolated from endosperm on linear sucrose gradients. GA(3) treatment also resulted in increased RNA associated with ER. Malate synthase and catalase in crude homogenates were enhanced by 1 to 100 muM GA(3) concentrations. Isocitrate lyase, citrate synthase, malate synthase, catalase, and glycolate oxidase in isolated glyoxysomes were enhanced by 60, 20, 18, 40, and 28%, respectively, over controls. Treatment with abscisic acid led to decreased levels of glyoxysomal enzymes and reduced glyoxysomal protein. The effect of GA(3) and abscisic acid on the specific activities of glyoxysomes of different densities suggests that GA(3) influences enzyme levels and glyoxysome assembly.
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PMID:Effect of gibberellin a(3) on the endoplasmic reticulum and on the formation of glyoxysomes in the endosperm of germinating castor bean. 1666 May 35

Mitochondria isolated from pea leaves (Pisum sativum L. var Massey Gem) and purified on a linear sucrose density gradient were substantially free of contamination by Chl and peroxisomes. They showed high respiratory rates and good respiratory control and ADP/O ratios. Malate, glutamate, succinate, glycine, pyruvate, alpha-ketoglutarate, NADH, and NADPH were oxidized but little or no oxidation of citrate, isocitrate, or proline was detected. The oxidation of NADPH by the purified mitochondria did not occur via a transhydrogenase or phosphatase converting it to NADH. NADPH oxidation had an absolute requirement for added Ca(2+), whereas NADH oxidation proceeded in its absence. In addition, oxidation of the two substrates showed different sensitivities to chelators and sulfhydryl reagents, and faster rates of O(2) uptake were observed with both substrates than with either alone. This indicates that the NADPH dehydrogenase is distinct from the exogenous NADH dehydrogenase.
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PMID:Properties of substantially chlorophyll-free pea leaf mitochondria prepared by sucrose density gradient separation. 1666 78

Addition of NAD(+) to purified potato (Solanum tuberosum L.) mitochondria respiring alpha-ketoglutarate and malate in the presence of the electron transport inhibitor rotenone, stimulated O(2) uptake. This stimulation was prevented by incubating mitochondria with N-4-azido-2-nitrophenyl-aminobutyryl-NAD(+) (NAP(4)-NAD(+)), an inhibitor of NAD(+) uptake, but not by 1 mm EGTA, an inhibitor of external NADH oxidation. NAD(+)-stimulated malate-cytochrome c reductase activity, and reduction of added NAD(+) by intact mitochondria, could be duplicated by rupturing the mitochondria and adding a small quantity to the cuvette. The extent of external NAD(+) reduction was correlated with the amount of extra mitochondrial malate dehydrogenase present. Malate oxidation by potato mitochondria depleted of endogenous NAD(+) by storing on ice for 72 hours, was completely dependent on added NAD(+), and the effect of NAD(+) on these mitochondria was prevented by incubating them with NAP(4)-NAD(+). External NAD(+) reduction by these mitochondria was not affected by NAP(4)-NAD(+). We conclude that all effects of exogenous NAD(+) on plant mitochondrial respiration can be attributed to net uptake of the NAD(+) into the matrix space.
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PMID:Exogenous NAD Effects on Plant Mitochondria: A Reinvestigation of the Transhydrogenase Hypothesis. 1666 22

Glyoxysomes isolated from castor bean (Ricinus communis L., var Hale) endosperm had NADH:ferricyanide reductase and NADH:cytochrome c reductase activities averaging 720 and 140 nanomole electrons/per minute per milligram glyoxysomal protein, respectively. These redox activities were greater than could be attributed to contamination of the glyoxysomal fractions in which 1.4% of the protein was mitochondrial and 5% endoplasmic reticulum. The NADH:ferricyanide reductase activity in the glyoxysomes was greater than the palmitoyl-coenzyme A (CoA) oxidation activity which generated NADH at a rate of 340 nanomole electrons per minute per milligram glyoxysomal protein. Palmitoyl-CoA oxidation could be coupled to ferricyanide or cytochrome c reduction. Complete oxidation of palmitoyl-CoA, yielding 14 nanomole electrons/per nanomole palmitoyl-CoA, was demonstrated with the acceptors, NAL, cytochrome c, and ferricyanide. Malate was also oxidized by glyoxysomes, if acetyl-CoA, ferricyanide, or cytochrome c was present. Glyoxysomal NADH:ferricyanide reductase activity has the capacity to support the combined rates of NADH generation by beta-oxidation and the glyoxylate cycle.
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PMID:beta-Oxidation and Glyoxylate Cycle Coupled to NADH: Cytochrome c and Ferricyanide Reductases in Glyoxysomes. 1666 78

Mitochondria isolated from mesophyll protoplasts differed from mitochondria isolated directly from leaves of Avena sativa in that protoplast mitochondria (a) had a lower overall respiratory capacity, (b) were less able to use low concentrations of exogenous NADH, (c) did not respond rapidly or strongly to added NAD, (d) appeared to accumulate more oxaloacetate, and (e) oxidized both succinate and tetramethyl-p-phenylene-diamine (an electron donor for cytochrome oxidase) more slowly than did leaf mitochondria. It is concluded that cytochrome oxidase activity was inhibited, the external NADH dehydrogenase had a reduced affinity for NADH, succinate oxidation was inhibited, NAD and oxaloacetate porters were probably inhibited, and accessibility to respiratory paths may have been reduced in protoplast mitochondria. The results also suggest that there was a reduced affinity of a succinate porter for this substrate in oat mitochondria. In addition, all oat mitochondria required salicylhydroxamic acid (SHAM) as well as cyanide to block malate and succinate oxidation. Malate oxidation that did not appear to saturate the cytochrome pathway was sensitive to SHAM in the absence of cyanide, suggesting that the oat mitochondria studied had concomitant alternative and subsaturating cytochrome oxidase pathway activity.
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PMID:Respiration of Mitochondria Isolated from Leaves and Protoplasts of Avena sativa. 1666 11


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