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:1.6.5.3 (complex I)
8,901 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The site of Na+-dependent activation in the respiratory chain of the marine bacterium, Vibrio alginolyticus, was investigated. The respiratory chain system contained ubiquinones (Q), menaquinones (MK), cytochromes b(560), c(553), d(630), and o(560). The membrane-bound and partially purified NADH dehydrogenase was stimulated 2- to 3-fold by the addition of 0.2 M Na+ or K+ and no specific requirement for Na+ was observed in this reaction step. The cytochrome oxidase showed no requirement for monovalent cations. The respiratory activity (NADH oxidase) of the membrane was lost on removal of the quinones, and the reincorporation of authentic Q-10 or MK-4 restored the activity. The rate of MK-4 reduction by NADH (menaquinone reductase) as measured using MK-4 incorporated membrane was activated by Na+, but only slightly by K+. The apparent Ka for Na+ was 78 mM for both menaguinone reductase and NADH oxidase. The requirement for Na+ of menaquinone reductase was greatly reduced in the presence of 0.2 M K+. Ubiquinone reductase as measured by using Q-10 incorporated membrane was also activated more effectively by Na+ than by K+. These results strongly suggested that the site of Na+-dependent activation in the respiratory chain of marine V. alginolyticus was at the step of NADH; quinone oxidoreductase.
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PMID:NADH: quinone oxidoreductase as a site of Na+-dependent activation in the respiratory chain of marine Vibrio alginolyticus. 45 42

Cells of Rhodopseudomonas capsulata, strain 37b4, leu-, precultivated anaerobically under low light intensity, were exposed to high light intensity (2000 W.m-2). The cells grew with a mass doubling time of 3 h. The synthesis of bacteriochlorophyll (BChl) began after two doublings of cell mass. Reaction center and light-harvesting BChl I (B-875) were the main constituents of the photosynthetic apparatus incorporated into the membrane. The size of the photosynthetic unit (total BChl/reaction center) decreased and light-harvesting BChl I became the dominating BChl species. Concomitant with the appearance of the different spectral forms of BChl the respective proteins were incorporated into the membrane, i.e. the three reaction center polypeptides, the polypeptide associated with light-harvesting BChl I, the two polypeptides associated with BChl II. A polypeptide of an apparent molecular weight of 45 000 was also incorporated. A lowering of the light intensity to 7 W.m-2 resulted in a lag phase of growth for 6 h. Afterwards, the time for doubling of cell mass was 11 h. The concentration of all three BChl complexes (reaction center, light-harvesting BChl I and II complexes)/cell and per membrane protein increased immediately. Also the size of the photosynthetic unit and the amount of intracytoplasmic membranes/cell increased. The activities of photophosphorylation, succinate dehydrogenase, NADH dehydrogenase and NADH oxidation (respiratory chain)/membrane protein are higher in membrane preparations isolated from cells grown at high light intensities than in such preparations from cells grown at low light intensities.
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PMID:Effects of light intensity on membrane differentiation in Rhodopseudomonas capsulata. 48 32

We have previously classified 35 of our respiration-deficient mutants into seven complementation groups and one "overlapping" mutant which does not complement mutants from groups I and II. In this paper we report on the biochemical characterization of representatives of complementation groups I, II, VII, and the "overlapping" mutant. We show that these mutants all have a defect in complex I of the electron-transport chain. The general features of these mutants are: (1) a low rate of O2 consumption in whole cells; (2) a low rate of release of 14CO2 from [2-14C] pyruvate, [1-14C] pyruvate, and [3-14C] beta-hydroxybutyrate; (3) a low rate of release of 14CO2 from [5-14C] glutamate and [1-14C] glutamate in mutants from groups II, VII, and the "overlapping" mutant, whereas a significant amount of 14CO2 is released in mutants from group I; (4) a substantial rate of release of 14CO2 from [U-14C] asparate; (5) in isolated mitochondria, succinate and alpha-glycerol phosphate stimulate O2 consumption whereas substrates which generate NADH, such as malate, do not; and (6) there is little or no rotenone-sensitive NADH oxidase activity in isolated mitochondria.
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PMID:Respiration-deficient Chinese hamster cell mutants: biochemical characterization. 49 59

X-band electron-paramagnetic-resonance spectroscopy at 4.2--77K combined with measurements of oxidation-reduction potential was used to identify iron--sulphur centres in Arum maculatum (cuckoo-pint) mitochondria. In the oxidized state a signal with a derivative maximum at g = 2.02 was assigned to succinate dehydrogenase centre S-3. Unreduced particles showed additional signals at g = 2.04 and 1.98 (at 9.2 GHz), which may be due to a spin-spin interaction. In the reduced state a prominent signal at g = 1.93 and 2.02 was resolved into at least three components that could be assigned to centres S-1 and S-2 of succinate dehydrogenase (midpoint potentials -7 and -240 mV respectively at pH 7.2) and a small amount of centre N-1b (e'o= -240 mV) of NADH-ubiquinone reductase. In addition, changes in line shape around -10 mV indicated the presence of a fourth component in this signal. The latter was more readily reduced by NADH than by succinate, suggesting that it might be associated with the external NADH dehydrogenase. The iron-sulphur centres of NADH-ubiquinone reductase were present in an unusually low concentration, indicating that the alternative, non-phosphorylating, NADH dehydrogenase containing a low number of iron-sulphur centres may be responsible for most of the high rate of oxidation of NADH.
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PMID:Iron-sulphur centres in mitochondria from Arum maculatum spadix with very high rates of cyanide-resistant respiration. 59 30

A membrane-bound NADH dehydrogenase, solubilized and partially purified from a marine bacterium Photobacterium phosphoreum, contains FAD as the prosthetic group, and is specific for NADH. Ferricyanide, various other redox dyes and cytochrome c can act as electron acceptors. The enzymatic activity when assayed with electron acceptors other than cytochrome c, is activated by monovalent cations (Na+ and K+) and deactivated by high concentrations of monovalent anions (SCN-, NO3-, and Cl-) but not by phosphate ions. The enzymatic reaction follows a ping-pong mechanism and kinetic analysis of the enzyme showed that the activation by monovalent cations is due to increase of affinity of the enzyme for substrates; Vm was not affected. The increase of affinity was 62- and 46-fold for NADH and 57- and 31-fold for 2,6-dichlorophenol indophenol in the presence of Na+ and K+, respectively. On the other hand, NADH-cytochrome c reductase activity of the enzyme was strongly inhibited by these cations.
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PMID:Properties and kinetics of salt activation of a membrane-bound NADH dehydrogenase from a marine bacterium Photobacterium phosphoreum. 72 93

Acholeplasma laidlawii A consists of pleomorphic cell clusters surrounded by a single membrane. When lysed, a cell gives rise to several membrane fragments which cannot be separated from each other by isopycnic sucrose gradient centrifugation. A heterogeneous lateral organization of the cell membranes was detected by countercurrent distribution of membrane fragments in a two-polymer aqueous phase system. It revealed that the membranes consist of at least two subpopulations with respect to surface properties. Changes in the fatty acid and cholesterol content of the membranes revealed that the resolution of different subpopulations was predominantly due to a critical ratio of monoglucosyldiglyceride to diglucosyldiglyceride. The heterogeneity of the membrane probably depends on lipid-lipid and lipid-protein steric interactions. Charged lipids, an apolar monoglucolipid and the ratio between lipids and proteins also affect membrane partition. The differences in the subpopulations were further reflected by different specific activities of NADH dehydrogenase, NADH oxidase and ATPase. These activities varied independently. Minor quantitative differences in the protein patterns of different subpopulations were apparent. The origin and the preservation of the membrane subpopulations are discussed in terms of lipid-lipid and lipid-protein interactions, their age and energy metabolism.
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PMID:Fractionation of membranes from Acholeplasma laidlawii A on the basis of their surface properties by partition in two-polymer aqueous phase systems. 76 Jul 84

The NADH dehydrogenase of the Escherichia coli respiratory chain has been identified by the following properties: (a) its location in membrane vesicles; (b) its inhibition by AMP in a fashion similar to that of the NADH oxidase; (c) its specificity for NADH, but not NADPH, with the same Km for NADH as that of the NADH oxidase; (d) its sensitivity when membrane-bound to inhibition by dicoumarol, rotenone, and 2-heptyl-4-hydroxyquinoline-N-oxide, which are also inhibitors for the NADH oxidase. The NADH-dehydrogenase of the cytosol fraction (assayed as NADH-dichlorphenolindophenol reductase activity) differs substantially from the membrane-bound activity both in substrate specificity and in the inhibitors of the reaction. The respiratory chain NADH dehydrogenase was extracted from isolated membrane vesicle preparations by solubilization in Triton X-100, and was purified in buffers containing that detergent. The purification employed chromatography on DEAE-cellulose, precipitation by 30% ethanol, and chromatography on hydroxyalapatite and DEAE-agarose. The most highly purified preparations of the enzyme were homogeneous in migration on polyacrylamide gels containing Triton X-100, at pH 9.5, where one band accounted for all of the protein and activity. Electrophoresis on polyacrylamide gels containing sodium dodecul sulfate showed 1 band of molecular weight 38,000, which accounted for over 75% of the protein on the gel. Because of requirements for either Triton X-100 or phospholipid for activity of the purified enzyme, it is difficult to estimate the level of purification achieved over isolated membrane vesicles. However, we estimate that the enzyme was purified some 30-fold over membrane vesicles, or some 300-fold over whole cells.
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PMID:The NADH dehydrogenase of the respiratory chain of Escherichia coli. I. Properties of the membrane-bound enzyme, its solubilization, and purification to near homogeneity. 78 86

A strain carrying a point mutation affecting the NADH dehydrogenase complex of Escherichia coli has been isolated and its properties examined. The gene carrying the mutation (designated ndh) was located on the E. coli chromosome at about minute 23 and was shown to be cotransducible with the pyrC gene. Strain carrying the ndh- allele were found to be unable to grow on mannitol and to grow very poorly on glucose unless the medium was supplemented with succinate, acetate or casamino acids. The following properties of strains carrying the ndh- allele were established which suggest that the mutation affects the NADH dehydrogenase complex but apparently not the primary dehydrogenase. Membrane preparations possess normal to elevated levels of D-lactate oxidase and succinate oxidase activities but NADH oxidase is absent. NADH is unable to reduce ubiquinone in the aerobic steady state and reduces cytochrome b very slowly when the membranes become anaerobic. NADH dehydrogenase, measured as NADH-dichlorophenolindophenol reductase is reduced but not absent. NADH oxidase is stimulated by menadione although not by Q-3 or MK-1 and in the presence of menadione, cytochrome b is reduced normally by NADH. Further mutants affected in NADH oxidase were isolated using a screening procedure based on the growth characteristics of the original ndh- strain. The mutantions carried by these strains were all cotransducible with the pyrC gene and the biochemical properties of the additional mutants were similar to those of the original mutant. The properties of the group of ndh- mutants established so far suggest that they are affected in the transfer of reducing equivalents from the NADH dehydrogenase complex to ubiquinone.
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PMID:Mutations affecting the reduced nicotinamide adenine dinucleotide dehydrogenase complex of Escherichia coli. 79 16

The fungicide dexon (p-dimethylaminobenzenediazosulfonate, Na-salt) inhibits the NADH oxidase activity of submitochondrial particles (ETP) from beef heart (semi-inhibition concentration 1.4 muM), while the succinate oxidase activity is unaffected. Measurements of the activity of several enzymatic partial reactions of the respiratory chain of ETP suggest that dexon acts directly on the flavine of NADH dehydrogenase. Soluble NADH-cytochrome c-oxidoreductase (MAHLER) and rotenone-insensitive NADH ubiquinone reductase are also inhibited by dexon. At low concentrations of dexon, inhibition of ETP starts slowly only after addition of NADH. Preincubation without NADH increases the amount of inhibition, but does not prevent the time delay. It is assumed that an electron flux through the respiratory chain, or reduction of flavine is prerequisite for the reaction of dexon with the action site. Furthermore, dexon inhibits the NADH dehydrogenase located at the outer surface of the inner membrane of plant mitochondria, accessible to extramitochondrial NADH and insensitive to rotenone, as has been shown on isolated mitochondria from cauliflower (Brassica oleracea L). In addition, dexon inhibits selectively the NADH dehydrogenase of the DT diaphorase (ERNSTER) from rat liver cytosol. In contrast, the dicoumarol-insensitive NADH dehydrogenase (ZINSMEYER et al.) from rat liver cytosol, the NADH-cytochrome b5-reductase (STRITTMATTER) from rat liver microsomes, the rotenone-insensitive NADH-cytochrome c-oxidoreductase of the outer membrane of rat liver mitochondria, soluble NADH-oxidase from Escherichia coli, and NADH-dehydrogenase from human erythrocytes are not inhibited. The results suggest that dexon is a group reagent to certain pyridine nucleotide-dependent flavine enzymes.
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PMID:[Action of the systemic fungicide dexon on several NADH dehydrogenases]. 82 48

Treating bovine epididymal spermatozoa with rutamycin or rotenone inhibited both respiration and motility supported by endogenous substrates. When oxidative phosphorylation had been blocked with various inhibitors, pyruvate was metabolized to yield ATP and restored motility. Fructose, which is metabolized via glycolysis to yield ATP, was also able to resuscitate the cells. Other substrates tested (lactate, acetate, alpha-ketoglutarate, or glyoxylate) were unable to restore motility in rutamycin-treated cells. In the presence of pyruvate, the phosphorylation uncoupler, carbonylcyanide-p-trifluoromethyoxphenylhydrazone, reduced motility and ATP to common levels in untreated cells or cells treated with rutamycin or rotenone. Pyruvate is thus metabolized to produce ATP by a pathway independent of oxidative phosphorylation associated with the electron transport chain. 5-Methoxyindole-2-carboxylic acid, an inhibitor of lipoyldehydrogenase, prevented the increase of motility and ATP in rutamycin-treated cells, indicating that alpha-keto acid oxidation is involved in the production of ATP from pyruvate when rutamycin is present. With pyruvate present, bongkrekic acid, antimycin A, and anaerobiosis eliminated motility, reduced ATP to low levels, and also significantly reduced the rate of pyruvate metabolism. Acetate was produced from pyruvate only when cellular ATP concentrations were low. Decreases in free carnitine concentrations showed that pyruvate initially used was converted to acetylcarnitine. The results indicate that the intramitochondrial lactate dehydrogenase X, which is unique to spermatozoa, allows the NADH resulting from pyruvate oxidation to reduce other pyruvate molecules to lactate. Pyruvate thus competes with, and can substitute for, the NADH dehydrogenase of the electron transport chain. Pyruvate rapidly repletes the acetylcarnitine pool under a variety of conditions.
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PMID:Pyruvate metabolism in bovine epididymal spermatozoa. 83 18


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