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)

Stromal ribosomes and those bound to thylakoid membranes were prepared from intact spinach chloroplasts which were purified on Percoll gradients. The products of read-out translation of these ribosomes supplemented with an Escherichia coli extract were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Striking similarity was found between the polypeptides labeled in the read-out translation of the chloroplastic ribosomes and those synthesized in isolated chloroplasts. Among the polypeptides translated on thylakoid-bound ribosomes, apoprotein of chlorophyll-protein complex I, alpha and beta subunits of coupling factor 1, and 32,000-Da membrane polypeptide were identified from their mobility on the polyacrylamide gel. The large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase and other several stromal proteins were translated exclusively from stromal ribosomes. However, when the translation was programmed in cell-free systems from either E. coli, wheat germ, or rabbit reticulocytes by RNAs isolated separately from stroma and thylakoids, no qualitative difference was found between the products from those RNAs. These results suggest that thylakoid-bound ribosomes are the main sites of synthesis of thylakoid proteins and stromal-free ribosomes are that of stromal proteins, and that thylakoids and stroma contain mRNAs for the stromal and the thylakoid proteins, respectively, in a form not functioning in the chloroplasts.
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PMID:Thylakoid membranes: the translational site of chloroplast DNA-regulated thylakoid polypeptides. 651 2

A photoaffinity-labelling analogue of the respiratory inhibitor rotenone was synthesized from the naturally occurring rotenoid amorphigenin. The analogue inhibits NADH-ubiquinone oxidoreductase activity at concentrations comparable with those of rotenone. Photolysis of the radiolabelled analogue bound to isolated NADH-ubiquinone oxidoreductase resulted in preferential incorporation of radioactivity into a polypeptide of Mr 33 000, particularly at low concentrations of the inhibitor. Preparations of the enzyme differ in a parallel fashion in the content of this polypeptide, the degree of photolabelling by the analogue and their sensitivity to rotenone, providing further evidence that the 33 000-Mr protein forms part of the rotenone-binding site.
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PMID:Photoaffinity labelling of mitochondrial NADH dehydrogenase with arylazidoamorphigenin, an analogue of rotenone. 651 63

Escherichia coli membrane particles were solubilized with potassium cholate. An NADH:ubiquinone oxidoreductase was resolved by hydroxylapatite chromatography of the solubilized material. This enzyme has been identified as the respiratory NADH dehydrogenase since it is absent in chromatograms of solubilized material from an ndh mutant strain. Such mutants lack membrane-bound NADH oxidase activity and have previously been shown to have an inactive NADH dehydrogenase complex [Young, I. G., & Wallace, B. J. (1976) Biochim. Biophys. Acta 449, 376-385]. The respiratory NADH dehydrogenase was amplified 50- to 100-fold in vivo by using multicopy plasmid vectors carrying the ndh gene and then purified to homogeneity on hydroxylapatite. Hydroxylapatite chromatography of cholate-solubilized material from genetically amplified strains purified the enzyme approximately 800- to 100-fold relatively to the activity in wild-type membranes. By use of a large-scale purification procedure, 50-100 mg of protein with a specific activity of 500-600 mumol of reduced nicotinamide adenine dinucleotide oxidized min-1 mg-1 at pH 7.5, 30 degrees C, was obtained. Sodium dodecyl sulfate gel electrophoresis of the purified enzyme showed that the enzyme consists of a single polypeptide with an apparent Mr of 45 000.
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PMID:Genetic identification and purification of the respiratory NADH dehydrogenase of Escherichia coli. 678 62

A fragment containing non-heme iron and acid-labile sulfide but little flavin can be solubilized from the mitochondrial NADH-ubiquinone oxidoreductase complex with chaotropic agents. This iron-protein fragment [Hatefi, Y., & Stempel, K. E. (1969) J. Biol. Chem. 244, 2350] has been resolved with detergents and ammonium sulfate fractionation into iron and acid-labile sulfide containing fractions, here called ISP-I and ISP-(II + III). ISP-I consists predominantly of a single polypeptide of molecular weight 75000. ISP-(II + III) consists predominantly of three polypeptides in equimolar concentrations with molecular weights of 49,000, 30000, and 13000. Treatment of the latter with sodium trichloroacetate followed by ammonium sulfate fraction results in separation of the 49000 molecular weight polypeptide from the two smaller subunits. Both of these subfractions (ISP-II and ISP-III, respectively) contain non-heme iron. The three iron-sulfur proteins have been characterized by their absorption spectra and iron and acid-labile sulfide contents. On the basis of the distribution of iron among the fractions obtained from chaotropic resolution of the NADH-ubiquinone oxidoreductase complex, a minimum of six or seven iron-sulfur centers are present in this enzyme.
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PMID:Purification of three iron-sulfur proteins from the iron-protein fragment of mitochondrial NADH-ubiquinone oxidoreductase. 680 41

Subunit II (with a molecular mass of about 24000 dalton, approximately 24 kDA) of NADH dehydrogenase from beef heart mitochondria was [ 14C ]carboxymethylated and cleaved with CNBr and proteolytic enzymes. Sequence analyses of purified fragments suggest that the subunit is composed of a homogeneous polypeptide chain, containing just over 230 residues. The primary structure of this chain was established except for a 14-residue internal part which was only determined by composition. The amino acid sequence suggests that four cysteine residues are involved in the binding of an iron-sulfur cluster. The subunit contains no long hydrophobic segment, in contrast to structures often found in membrane proteins, but in agreement with a model where the functional unit of NADH dehydrogenase in the membrane is shielded by other intra-membrane proteins. The polypeptide has a weak similarity to the iron-sulfur binding region of ferredoxin and has interesting but possibly insignificant similarities to parts of previously compared flavin-linked enzymes.
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PMID:The primary structure of subunit II of NADH dehydrogenase from bovine-heart mitochondria. 686 57

Highly purified preparations of the cholate-solubilized respiratory NADH dehydrogenase, isolated from genetically amplified Escherichia coli strains [Jaworowski, A., Campbell, H. D., Poulis, M. I., & Young, I. G. (1981) Biochemistry 20, 2041-2047], have been characterized. Enzyme preparations were shown to contain 70% (w/w) lipid, predominantly phosphatidylethanolamine. One mol of noncovalently bound FAD and approximately 1 mol of ubiquinone/mol of enzyme subunit were detected. The purified enzyme was shown to contain only low levels of Fe and acid-labile S, indicating the absence of iron-sulfur clusters. No Cu, Mo, W, or covalently bound P was detected, and no evidence for other chromophores was obtained from visible and ultraviolet absorption spectra of the purified enzyme or of the delipidated polypeptide prepared by gel filtration in sodium dodecyl sulfate. Protein chemical studies verified that the enzyme consists of a single polypeptide species of Mr 47 000, and the N- and C-terminal cyanogen bromide peptides were identified. The pure enzyme was shown to reconstitute membrane-bound, cyanide-sensitive NADH oxidase activity in membrane vesicles prepared from ndh mutant strains.
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PMID:Characterization of the respiratory NADH dehydrogenase of Escherichia coli and reconstitution of NADH oxidase in ndh mutant membrane vesicles. 702 Jul 57

Mitochondrial NADH dehydrogenase may be isolated from bovine heart as a lipoprotein complex (Complex I or NADH-ubiquinone oxidoreductase). Polypeptide subunits that are exposed to the hydrophobic region of the phospholipid bilayer were identified by photolabelling with the hydrophobic probe, 5-[125I]iodonaphth-1-yl azide. Chaotropic resolution of the labelled enzyme showed that the hydrophilic flavoprotein and iron-protein fragments of the enzyme were not in contact with the phospholipid bilayer. When complex I that had been partially depleted of phospholipids was photolabelled, incorporation of radioactivity into certain polypeptides was increased, indicating either conformational changes in protein or preferential association of these polypeptides with residual cardiolipin. A model NADH dehydrogenase structure is proposed on the basis of these results and those obtained with hydrophilic probes by Smith & Ragan (1980) Biochem. J. 185, 315-326.
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PMID:Identification of the subunits of bovine heart mitochondrial NADH dehydrogenase that are exposed to the phospholipid bilayer by photo-labelling with 5-iodonaphth-1-yl azide. 723 4

The binding of ganglioside GM1 to bovine serum albumin has been studied by using absorption and fluorescence properties of the protein chromophores. Differences in the ultraviolet absorption spectrum and in fluorescence quenching, as well as a marked shift of the wavelength at the fluorescence maximum provide information about the binding of this ganglioside to albumin. Ultracentrifugal studies showed that there are two forms of the GM1-protein complexes which differ markedly in their molecular weight. These two forms have been separated on this basis, by a chromatographic sieving procedure, and designated as complexes I and II. Both complexes are characterized by a GM1: protein ratio of one ganglioside micelle per albumin polypeptide chain. Complex II polymerizes slowly and irreversibly to a dimer, complex I. These results have been correlated with the optical studies in order to draw limited inferences as to the environment of the binding sites on the native protein. The interaction between GM1 micelles and albumin is mostly hydrophobic and the two complexes are actually mixed ganglioside-protein micelles. At submicellar concentrations of ganglioside a binding of ganglioside GM1 to albumin also occurs. This process is due, however, to an aspecific, reversible adhesion of GM1 molecules on the albumin surface with no apparent perturbation of the albumin structure.
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PMID:Interaction of GMI ganglioside with bovine serum albumin: formation and isolation of multiple complexes. 746 Aug 98

A pseudogene, psi nad7, which has significant sequence similarity (66.7% amino acid identity) with the bovine nuclear gene for a 49 kDa subunit of the NADH dehydrogenase (NADH:ubiquinone oxidoreductase, EC 1.6.99.3), has been identified on the mitochondrial genome of the liverwort Marchantia polymorpha. The predicted coding region, which includes six termination codons, is actively transcribed into RNA molecules of 16 and 9.6 kb in length, but RNA splicing products were not detected in the liverwort mitochondria. Genomic DNA blot analysis and RNA blot analysis using poly(A)+ RNA suggest that a structurally related nuclear gene encodes the mitochondrial ND7 polypeptide. These results imply that this psi nad7 is a relic of a gene transfer event from the mitochondrial genome into the nuclear genome during mitochondrial evolution in M. polymorpha.
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PMID:Active transcription of the pseudogene for subunit 7 of the NADH dehydrogenase in Marchantia polymorpha mitochondria. 760 35

In Nicotiana sylvestris, two cytoplasmic male sterile (CMS) mutants obtained by protoplast culture show abnormal developmental features of both vegetative and reproductive organs, and mitochondrial gene reorganization following homologous recombination between 65 bp repeated sequences. A mitochondrial region of 16.2 kb deleted from both CMS mutants was found to contain the last two exons of the nad7 gene coding for a subunit of the mitochondrial respiratory chain complex I, which is encoded in the nucleus in fungi and animals but was recently found to be encoded by the mitochondrial genome in wheat. Although the N. sylvestris nad7 gene shows strong homology with its wheat counterpart, it contains only three introns instead of four. Polymerase chain reaction (PCR) experiments indicated that the parental gene organization, including the complete nad7 gene, is probably maintained at a substoichiometric level in the CMS mutants, but this proportion is too low to have a significant physiological role, as confirmed by expression studies showing the lack of detectable amounts of the NAD7 polypeptide. Consequently, absence of NAD7 is not lethal to plant cells but a deficiency of complex I could be involved in the abnormal CMS phenotype.
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PMID:Deletion of the last two exons of the mitochondrial nad7 gene results in lack of the NAD7 polypeptide in a Nicotiana sylvestris CMS mutant. 765 30


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