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 highly purified respiratory chain NADH dehydrogenase (EC 1.6.99.3) of Escherichia coli is inactive in the absence of detergent or phospholipid. Triton X-100 is the detergent that gives optimal activity, but the Triton X-100-activated enzyme is stimulated an additional 2-fold by E. coli phospholipids. Phosphatidylglycerol and diphosphatidylglycerol are the most effective lipid activators. The activated complex prepared with diphosphatidylglycerol is stable, whereas that with phosphatidylglycerol loses activity rapidly. Maximum activation by phospholipids occurs after preincubation at 0 degrees C and at pH 7. Triton X-100 is required at low concentrations for lipid activation, but high concentrations interfere with the activation. When the enzyme is optimally activated by phospholipids, it may be additionally activated 2-fold by spermidine, but not by magnesium. In contrast, the Triton X-100-activated form of the enzyme is stimulated by several divalent cations, without specificity. Thus, the most stable, active form of the purified NADH dehydrogenase is generated in the presence of diphosphatidylglycerol and spermidine.
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PMID:Specific phospholipid requirement for activity of the purified respiratory chain NADH dehydrogenase of Escherichia coli. 1 60

Preparations of NADH-ubiquinone reductase from bovine heart mitochondria (Complex I) were shown to contain at least 16 polypeptides by gel electrophoresis in the presence of sodium dodecyl sulphate. 2. High-molecular-weight soluble NADH dehydrogenase prepared from Triton X-100 extracts of submitochondrial particles [Baugh & King (1972) Biochem. Biophys. Res. Commun. 49, 1165-1173] was similar to Complex I in its polypeptide composition. 3. Solubilization of Complex I by phospholipase A treatment and subsequent sucrose-density-gradient centrifugation did not alter the polypeptide composition. 4. Lysophosphatidylcholine treatment of Complex I caused some selective solubilization of a polypeptide of mol.wt. 33000 previosuly postulated to be the transmembrane component of Complex I in the mitochondrial membrane [Ragan (1975) in Energy Transducing Membranes: Structure, Function and Reconstitution (Bennun, Bacila & Najjar, eds.), Junk, The Hague, in the press]. 5. Chaotropic resolution of Complex I caused solubilization of polypeptides of molecular weights 75000, 53000, 29000, 26000 and 15500 and traces of others in the 10000-20000-mol.wt.range. 6. The major components of the iron-protein fraction from chaotropic resolution had molecular weights of 75000, 53000 and 29000, whereas the flavoprotein contained polypeptides of molecular weights 53000 and 26000 in a 1:1 molar ratio. 7. Iodination of Complex I by lactoperoxidase indicated that the water-soluble polypeptides released by chaotropic resolution, in particular those of the flavoprotein fraction, were largely buried in the intact Complex. 8. The polypeptides of molecular weights 75000, 53000, 42000, 39000, 33000, 29000 and 26000 were present in 1:2:1:1:1:1:1 molar proportions. The two subunits of molecular weight 53000 are probably non-identical.
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PMID:The structure and subunit composition of the particulate NADH-ubiquinone reductase of bovine heart mitochondria. 18 Sep 73

A carrier protein mediating alanine transport was purified from the membranes of the thermophilic bacterium PS3, by ion exchange chromatography in the presence of both Triton X-100 and urea. The alanine carrier was recovered in the nonadsorbed fraction from either DEAE- or CM-cellulose columns, suggesting that its isoelectric point was in the neutral pH region. The final preparation contained virtually no electron transfer components, ATPase, or NADH dehydrogenase. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed that the final preparation consisted of two major protein components with molecular weights of 36,000 and 9,400. Active transport of alanine after incorporation of the alanine carrier into reconstituted proteoliposomes was driven not only by an artificial membrane potential generated by potassium ion diffusion via valinomycin but also by mitochondrial cytochrome oxidase incorporated into the same liposomes and supplemented with both cytochrome c and ascorbic acid. The membrane-integrated portion (TFo) of the ATPase complex uncoupled alanine transport by conducting protons across the membrane.
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PMID:Isolation of the alanine carrier from the membranes of a thermophilic bacterium and its reconstitution into vesicles capable of transport. 19 18

Cytochrome c oxidase has been purified from rat liver mitochondria using affinity chromatography. The preparation contains 10.5 to 13.4 nmol of heme a + a3 per mg of protein and migrates as a single band during polyacrylamide gel electrophoresis under nondissociating conditions. It has a heme a/a3 ratio of 1.12 and is free of cytochromes b, c, and c1 as well as the enzymes, NADH dehydrogenase, succinic dehydrogenase, coenzyme Q-cytochrome c reductase, and ATPase. The enzyme preparation consists of six polypeptides having apparent Mr of 66,000, 39,000, 23,000, 14,000, 12,500 and 10,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The peptide composition is similar to those found for cytochrome c oxidases from other systems. The enzymatic activity of the purified enzyme is completely inhibited by carbon monoxide or cyanide, partially inhibited by Triton X-100 and dramatically enhanced by Tween 80 or phospholipids.
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PMID:Purification and characterization of cytochrome c oxidase from rat liver mitochondria. 21 98

The electron transfer complexes, succinate: ubiquinone reductase, ubiquinone: cytochrome c reductase, and cytochrome c: O2 oxidase were isolated from the mitochondrial membranes of Neurospora crassa by the following steps. Modification of the contents of the complexes in mitochondria by growing cells on chloramphenicol; solubilisation of the complexes by Triton X-100; affinity chromatography on immobilized cytochrome c and ion exchange and gel chromatography. Ubiquinone reductase was obtained in a monomeric form (Mr approximately 130 000) consisting of a flavin subunit (Mr 72 000) an iron-sulfur subunit (Mr 28 000) and a cytochrome b subunit (Mr probably 14 000). Cytochrome c reductase was obtained in a dimeric form (Mr approximately 550 000), the monomeric unit comprising the cytochromes b (Mr each 30 000), a cytochrome c1 (Mr 31 000), the iron-sulfur subunit (Mr 25 000), and six subunits without known prosthetic groups (Mr 9000, 11 000, 14 000, 45 000, 45 000, and 52 000). Cytochrome c oxidase was also isolated in a dimeric form (Mr approximately 320 000) comprising two copies each of seven subunits (Mr 9000, 12 000, 14 000, 18 000, 21 000, 29 000, and 40 000). The complexes were essentially free of phospholipid. Each bound one micelle of Triton X-100 (Mr approximately 90 000). After isolation, the bound Triton X-100 could be replaced by other nonionic detergents such as: alkylphenyl polyoxyethylene ethers, alkyl polyoxyethylene ethers and acyl polyoxyethylene sorbitan esters.
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PMID:Isolation of mitochondrial succinate: ubiquinone reductase, cytochrome c reductase and cytochrome c oxidase from Neurospora crassa using nonionic detergent. 22 65

The plasma membrane of the Ehrlich ascites tumor cell contains an NADH dehydrogenase. This activity was shown not to be due to contamination by other subcellular membranes. A variety of electron acceptors have been compared as to rate with the following result: ferricyanide greater than cytochrome c greater than cytochrome b5 greater than glyoxylate greater than dichlorophenolindophenol. Oxygen acceptance could not be detected. The optimum assay temperature and pH ranges were 30--40 degrees C and pH 6--8, respectively. With respect to either NADH or ferricyanide, the kinetics yielded linear double-reciprocal plots. Inhibition of the enzyme by sulfhydryl reagents could be blocked by excess NADH. Detergents such as Triton X-100 or cholate resulted in solubilization of the enzymatic activity, but phospholipase A2 did not. The activity differed from that of the mitochondria in that it was not inhibited by rotenone or antimycin A. The possible involvement of NADH oxidation in the energetics of plasma membrane transport is discussed.
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PMID:Electron-transferring enzymes in the plasma membrane of the Ehrlich ascites tumor cell. 42 30

The integral protein of cytochrome b556 after its solubilization with Triton X-100 from M. lysodeikticus membranes was studied. The cytochrome was found in complexes differing in charge and size during preparative gel electrophoresis and centrifugation in a sucrose concentration gradient. Cytochrome b556, being in complexes, retains its ability to be reduced by NADH dehydrogenase. The electron micrographs of the membranes after solubilization by Triton X-100 demonstrated the maintenance of the membrane structure. It is concluded that native protein complexes marked with cytochrome b556 are extracted from the membranes under their solubilization.
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PMID:[Cytochrome b556 complexes solubilized from Micrococcus lysodeikticus membranes by triton X-100]. 43 82

NADH dehydrogenase was isolated from M. lysodeikticus membranes with FAD as a prosthetic group. It was found the enzyme molecular weight is about 140000 in 0,01 M phosphate buffer, pH 7,4 in 1% Triton X-100. The enzyme molecules are dimers consisting of two subunits with molecular weight of 70000. The content of alpha-helical regions is 30%, that of beta-forms is 13%. The protein globule is cross-linked with the disulfide bonds and has hydrophobic regions on its surface.
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PMID:[Bacterial membrane proteins. Properties of Micrococcus lysodeikticus NADH dehydrogenase]. 45 11

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 highly purified preparation of NADH dehydrogenase was isolated from bacteria M. lysodeikticus membranes. The purification procedure involved extraction of the enzyme complex from isolated membranes by EDTA, solubilization of the complex by non-ionogenic detergent (1% Triton X-100), chromatography on DEAE-cellulose and electrofocussing in the pH gradient 4-6. The isoelectric point of the preparation is at 4.5; its main component is a protein with m.w. of about 76.000.
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PMID:[Proteins of bacterial membranes. Purification of NADH-dehydrogenase by electrofocusing]. 103 Jun 33


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