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

---

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

Treatment of submitochondrial particles (ETP) with trypsin at 0 degrees destroyed NADPH leads to NAD (or 3-acetylpyridine adenine dinucleotide, AcPyAD) transhydrogenase activity. NADH oxidase activity was unaffected; NADPH oxidase and NADH leads to AcPyAD transhydrogenase activities were diminished by less than 10%. When ETP was incubated with trypsin at 30 degrees, NADPH leads to NAD transhydrogenase activity was rapidly lost, NADPH oxidase activity was slowly destroyed, but NADH oxidase activity remained intact. The reduction pattern by NADPH, NADPH + NAD, and NADH of chromophores absorbing at 475 minus 510 nm (flavin and iron-sulfur centers) in complex I (NADH-ubiquinone reductase) or ETP treated with trypsin at 0 degrees also indicated specific destruction of transhydrogenase activity. The sensitivity of the NADPH leads to NAD transhydrogenase reaction to trypsin suggested the involvement of susceptible arginyl residues in the enzyme. Arginyl residues are considered to be positively charged binding sites for anionic substrates and ligands in many enzymes. Treatment of ETP with the specific arginine-binding reagent, butanedione, inhibited transhydrogenation from NADPH leads to NAD (or AcPyAD). It had no effect on NADH oxidation, and inhibited NADPH oxidation and NADH leads to AcPyAD transhydrogenation by only 10 to 15% even after 30 to 60 min incubation of ETP with butanedione. The inhibition of NADPH leads to NAD transhydrogenation was diminished considerably when butanedione was added to ETP in the presence of NAD or NADP. When both NAD and NADP were present, the butanedione effect was completely abolished, thus suggesting the possible presence of arginyl residues at the nucleotide binding site of the NADPH leads to NAD transhydrogenase enzyme. Under conditions that transhydrogenation from NADPH to NAD was completely inhibited by trypsin or butanedione, NADPH oxidation rate was larger than or equal to 220 nmol min-1 mg-1 ETP protein at pH 6.0 and 30 degrees. The above results establish that in the respiratory chain of beef-heart mitochondria NADH oxidation, NADPH oxidation, and NADPH leads to NAD transhydrogenation are independent reactions.
...
PMID:Oxidation of NADPH by submitochondrial particles from beef heart in complete absence of transhydrogenase activity from NADPH to NAD. 0 Mar 95

1. At 21 degrees C incubation of NADH-ubiquinone-1 reductase (Complex 1) with trypsin caused selective inhibition of nicotinamide nucleotide transhydrogenase activity. The reduction of K3Fe(CN)6 by NADH or NADPH was unaffected, but a slow decrease in the rate of reduction of ubiquinone-1 by NADH was observed. 2. The pH-dependence of nicotinamide nucleotide transhydrogenase activity differed in Complex I and trypsin-treated Complex I. The trypsin-labile activity had a pH optimum of approx. 6.5, whereas the trypsin-resistant activity had a pH optimum of approx. 5.5 or less. 3. The trypsinlabile transhydrogenase activity was specifically inhibited by butanedione or phenylglyoxal and was identified with the enzyme catalysing energy-linked transhydrogenase activity in submitochondrial particles. 4. Polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate revealed that trypsin caused degradation of a polypeptide of mol.wt 20500 in parallel with the loss of transhydrogenase activity. 5. At 30 degrees C and higher trypsin concentrations, the rate of reduction of K3Fe(CN)6 by NADH or NADPH slowly decreased. Increased lability of NADH-K3Fe(CN)6 reductase activity to trypsin was observed when the endogenous phospholipid of Complex I was depleted by detergent or phospholipase A treatment. 6. Polyacrylamide-gel electrophoresis indicated that removal of phospholipid allowed much more extensive degradation of constituent polypeptides by trypsin. The subunits of the low-molecular-weight (type II) dehydrogenase (53000 and 26000 mol.wt.) were, however, relatively resistant to trypsin even in phospholipid-depleted preparations.
...
PMID:The effects of proteolytic digestion by trypsin on the structure and catalytic properties of reduced nicotinamide-adenine dinucleotide dehydrogenase from bovine heart mitochondria. 0 40

The chlorophyll-protein complexes I and II have been isolated and anlyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis during greening and degreening of Chlamydomonas reinhardi y-1. At all stages of membrane formation, the complexes, when present, have a constant composition. Chlorophyll-protein complex I consists of a major polypeptide(s) of molecular weight 64,000 synthesized in the chloroplast, to which about 29 chlorophyll a molecules are bound. The complex is not detected when other polypeptides of chloroplastic origin, related to both Photosystem I and Photosystem II activities, are not synthesized. However, Photosystem I activity can develop in membranes in which chlorophyll-protein complex I is not detectable. Chlorophyll-protein complex II consists of two polypeptides of cytoplasmic origin, molecular weights 24,000 and 22,000, which bind 12 chlorophylls (a and b). The chlorophyll-protein complex II can be detected in membranes in which the development of photosystem II activity is prevented. Clipping of a Mr = 2000 fragment(s) from the Mr = 22,000 polypeptide following trypsin digestion of membranes, does not affect the complex. The detection of the complexes is possible only in membranes in which the simultaneous synthesis of both the chlorophyll and the corresponding polypeptides occurs. The 28,000 dalton polypeptide, reported to be present in the chlorophyll-protein complex II, comigrates with the complex but apparently is not part of the complex itself. The apparent molecular weight of the chlorophyll-protein complexes I and II are 88,000 and 28,000, respectively. The minimal true value for complex I is 89,000 or 154,000 and for complex II is 56,000.
...
PMID:Appearance and composition of chlorophyll-protein complexes I and II during chloroplast membrane biogenesis in Chlamydomonas reinhardi y-1. 84 36

The arrangement of the large (70,000-Mr) and small (30,000-Mr) subunits of succinate dehydrogenase in the mitochondrial inner membrane was investigated by immunoblot analysis of bovine heart mitochondria (right-side-out, outer membrane disrupted) or submitochondrial particles (inside-out) that had been subjected to surface-specific proteolysis. Both subunits were resistant to proteinase treatment provided that the integrity of the inner membrane was preserved, suggesting that neither subunit is exposed at the cytoplasmic surface of the membrane. The bulk of the small subunit appears to protrude into the matrix compartment, since the 30,000-Mr polypeptide is degraded extensively during limited proteolysis of submitochondrial particles without the appearance of an immunologically reactive membrane-associated fragment: moreover, a soluble 27,000-Mr peptide derived from this subunit is observed transiently on incubation with trypsin. Similar data obtained from the large subunit suggest that this polypeptide interacts with the matrix side of the inner membrane via two distinct domains; these are detected as stable membrane-associated fragments of 32,000 Mr and 27,000 Mr after treatment of submitochondrial particles with papain or proteinase K, although the 27,000-Mr fragment can be degraded further to low-Mr peptides with trypsin or alpha-chymotrypsin. A stable 32,000-34,000-Mr fragment is generated by a variety of specific and non-specific proteinases, indicating that it may be embedded largely within the lipid bilayer, or is inaccessible to proteolytic attack owing to its proximity to the surface of the intact membrane, possibly interacting with the hydrophobic membrane anchoring polypeptides of the succinate: ubiquinone reductase complex.
...
PMID:Topography of succinate dehydrogenase in the mitochondrial inner membrane. A study using limited proteolysis and immunoblotting. 199 68

The alkalophile NADH dehydrogenase (NADH: 2,6-dichlorophenolindophenol oxidoreductase) [EC 1.6.99.3] consists of two identical subunits of 65 kDa, and each subunit contains the catalytic and liposome-binding regions. On treatment with trypsin, the polypeptide exhibiting the liposome-binding property in one of the subunits was digested to form an enzymatically active hetero-dimer (40 and 65 kDa), and then the polypeptide in the other subunit was digested to form an active homo-dimer (40 and 40 kDa). The hetero-dimer bound to liposomes, but the homo-dimer did not. Kinetic analysis showed that removal of one or two of the polypeptides in the enzyme slightly affects its kinetic parameters. For all the enzyme species, NAD inhibited competitively with respect to NADH and non-competitively with respect to 2,6-dichlorophenolindophenol. The partially determined amino acid sequence of this alkalophile enzyme suggested that (i) a long random-coiled peptide (58 amino acid residues) or a portion of the peptide is located between the polypeptides with liposome-binding and catalytic properties, (ii) the polypeptide exhibiting liposome-binding property is in the amino terminal region of the enzyme, (iii) the amino acid sequences around the subtilisin and trypsin cleavage sites of the peptide are hydrophilic and on the surface of the protein molecule and therefore are susceptible to digestion, and (iv) the FAD-binding site is located near the amino terminal region of the catalytic region.
...
PMID:Tryptic digestion of NADH dehydrogenase from alkalophilic Bacillus. 276 20

Assimilatory nitrate reductase from Chlorella is a homotetramer which contains one of each of the prosthetic groups FAD, heme, and molybdenum per subunit. Besides the reduction of nitrate by NADH, nitrate reductase also catalyzes the partial activities NADH:cytochrome c reductase, NADH:ferricyanide reductase, and reduced methyl viologen:nitrate reductase. Incubation of native nitrate reductase with either trypsin, Staphylococcus aureus V8 protease, or a natural inactivator protease from corn results in a loss of NADH:nitrate reductase and NADH:cytochrome c reductase activities but no loss of reduced methyl viologen:nitrate reductase activity. Incubation of nitrate reductase with V8 protease or corn inactivator protease resulted in two different products, each of which retained a different partial activity. Reduced methyl viologen:nitrate reductase activity was associated with a homotetrameric fragment of about 260 kDa which contained heme and molybdenum but no FAD. The molecular mass of native nitrate reductase determined under the same conditions was 375 kDa. NADH:ferricyanide reductase activity was associated with a monomeric species of approximately 30 kDa which contained FAD and the NADH-binding site. These results are consistent with a structure-function model of nitrate reductase which has the following features: FAD/NADH-binding domains exposed on the surface of the molecule, a protease-sensitive hinge region which connects the nitrate-reducing and NADH dehydrogenase moieties, and the quaternary structure maintained via association sites on the heme/molybdenum domain.
...
PMID:Functional domains of assimilatory NADH:nitrate reductase from Chlorella. 301 63

Oxidative phosphorylation and Ca2+-transport functions of liver mitochondria were normalized in rats with alloxane diabetes after peroral administration of phytoecdisteroids - ecdisterone and turkesterone (5 mg/kg) or nerobol (10 mg/kg) within 15 days. These drugs normalized the activity of NADH dehydrogenase and succinate dehydrogenase in respiratory chain of mitochondria, increased distinctly stability of the enzymes to the effect of such factors as heating, effect of phospholipase A2 or trypsin.
...
PMID:[Comparative study of the effect of ecdysterone, turkesterone and nerobol on the function of rat liver mitochondria in experimental diabetes]. 377 12

An azidoubiquinone derivative, 3-azido-2-methyl-5-methoxy [3H]-6-decyl-1,4-benzoquinone ([3H]azido-Q), was used to study the ubiquinone-protein interaction and to identify ubiquinone-binding proteins in bovine heart mitochondrial succinate-ubiquinone reductase. When the reductase was incubated with [3H]azido-Q and illuminated with long wavelength UV light, the decrease in the enzymatic activity correlated with the amount of azido-Q incorporated into the protein. When the illuminated, [3H]azido-Q-treated reductase was extracted with organic solvent and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, radioactivity was found primarily in the QPs1 subunit. The [3H]azido-Q-labeled QPs1 was purified from labeled reductase by a procedure involving ammonium sulfate fractionation, dialysis, organic solvent extraction, lyophilization, preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and cold acetone precipitation. The purified, [3H]azido-Q-labeled QPs1 protein was subjected to reductive carboxymethylation prior to digestion by trypsin. One azido-Q-linked peptide, with a retention time of 66.9 min, was obtained by high performance liquid chromatographic separation. The partial amino-terminal sequence of this peptide is GLTISQL-, indicating that this tryptic peptide comprises amino acid residues 113-140 of the revised amino acid sequence of QPs1. The Q-binding domain, using the proposed structure of QPs1, is probably located in the stretch connecting transmembrane helices 2 and 3 that extrude from the surface of the M side of the inner membrane.
...
PMID:Identification of the ubiquinone-binding domain in QPs1 of succinate-ubiquinone reductase. 789 Jul 54

CAB-7p is a chlorophyll a/b binding protein of photosystem I (PSI). It is found in light-harvesting complex I 680 (LHCI-680), one of the chlorophyll complexes produced by detergent solubilization of PSI. Two types of evidence are presented to indicate that assembly of CAB-7p into PSI proceeds through a membrane intermediate. First, when CAB-7p is briefly imported into chloroplasts or isolated thylakoids, we initially observe a fast-migrating membrane form of CAB-7p that is subsequently converted into PSI. The conversion of the fast-migrating form into PSI does not require stroma or ATP. Second, trypsin treatment of thylakoids containing radiolabeled CAB-7p indicates that there are at least two membrane forms of the mature 23-kD protein. The predominant form is completely resistant to proteolysis; a second form of the protein is cleaved by trypsin into 12- and 7-kD polypeptides. We interpret this to mean that the intermediate is a cleavable form that becomes protease resistant during assembly. This notion is supported by the observation that CAB-7p in LHCI-680 is largely cleaved by trypsin into 12- and 7-kD polypeptides, whereas CAB-7p in isolated PSI particles is trypsin resistant. In vitro, we generated a mutant form of CAB-7p, CAB-7/BgI2p, that was able to integrate into thylakoid membranes but was unable to assemble into PSI. The membrane form of CAB-7/BgI2p, like LHCI-680, was predominantly cleaved by trypsin into 12- and 7-kD fragments. We suggest that the mutant protein is arrested at an intermediate stage in the assembly pathway of PSI. Based on its mobility in nondenaturing gels and its susceptibility to protease cleavage, we suggest that the intermediate form is LHCI-680. We propose the following distinct stages in the biogenesis of LHCI: (a) apoprotein is integrated into the thylakoid, (b) chlorophyll is rapidly bound to apoprotein forming LHCI-680, and (c) LHCI-680 assembles into the native PSI complex.
...
PMID:Biogenesis of a photosystem I light-harvesting complex. Evidence for a membrane intermediate. 810 5

The Rhodobacter capsulatus genes encoding the NUOE and NUOF subunits, equivalent to the 24 kDa and 51 kDa subunits of the mammalian mitochondrial complex I, have been sequenced. According to the nucleotide sequence, the NUOE subunit is 389 amino acids long and has a molecular mass of 41.3 kDa. In comparison to the mitochondrial equivalent subunit, NUOE is extended at the C terminus by more than 150 amino acids. The NUOF subunit is 431 amino acids long and has a molecular mass of 47.1 kDa. A subcomplex containing both the NUOE and NUOF subunits was extracted by detergent treatment of R. capsulatus membranes and immuno-purified. This subcomplex is homologous to the mitochondrial FP fragment. Mass spectrometry after trypsin treatment of the NUOE subunit validates the atypical primary structure deduced from the sequence of the gene.
...
PMID:Immuno-purification of a dimeric subcomplex of the respiratory NADH-CoQ reductase of Rhodobacter capsulatus equivalent to the FP fraction of the mitochondrial complex I. 910 16


1 2 3 Next >>

---