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:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of mild hypothermia on Na(+)-K+ ATPase and lipid peroxidation in canine brain tissue following a 18-minute cardiac arrest and resuscitation for 8 hours were studied. Mild hypothermia improved the restoration of the activity of Na(+)-K+ ATPase, LDH, protect the activity of SOD, decrease the loss of GSH, but not completely blocked the ischemia reperfusion induced lipid peroxidation.
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PMID:[Effects of mild hypothermia on Na(+)-K+ ATPase and lipid peroxidation in canine brain tissue following cardiac arrest and resuscitation]. 1068 82

Translocase mediates preprotein translocation across the Escherichia coli inner membrane. It consists of the SecYEG integral membrane protein complex and the peripheral ATPase SecA. Here we show by functional assays, negative-stain electron microscopy and mass measurements with the scanning transmission microscope that SecA recruits SecYEG complexes to form the active translocation channel. The active assembly of SecYEG has a side length of 10.5 nm and exhibits an approximately 5 nm central cavity. The mass and structure of this SecYEG as well as the subunit stoichiometry of SecA and SecY in a soluble translocase-precursor complex reveal that translocase consists of the SecA homodimer and four SecYEG complexes.
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PMID:SecYEG assembles into a tetramer to form the active protein translocation channel. 1069 27

SecA ATPase is critical for protein translocation across the Escherichia coli inner membrane. To understand this activity further, the high affinity nucleotide binding activity of SecA was characterized. We found that at 4 degrees C SecA homodimer binds one ADP molecule with high affinity. This nucleotide binding activity was conformationally regulated by temperature: at low temperature SecA affinity for ADP was high with a slow exchange rate, whereas at high temperature the converse was true. Azi- and PrlD-SecA proteins that confer azide-resistant and signal sequence suppressor phenotypes were found to have reduced affinity for ADP and accelerated exchange rates compared with wild type SecA. Consistent with this observation, fluorescence and proteolysis studies indicated that these proteins had a conformationally relaxed state at a reduced temperature compared with SecA. The level of Azi- and PrlD-SecA protein was also elevated in inverted membrane vesicles where it displayed higher membrane ATPase activity. These results provide the first direct evidence for conformational regulation of the SecA-dependent nucleotide cycle, its alteration in azi and prlD mutants, and its relevance to in vivo protein export.
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PMID:Nucleotide binding activity of SecA homodimer is conformationally regulated by temperature and altered by prlD and azi mutations. 1074 39

This study investigated the effects of quantity and type of diet fed to superovulated donor heifers on molecular and metabolic indices of embryonic development. These effects included the relative abundances of mRNAs for the alpha 1 subunit of Na/K-ATPase and the antioxidant enzyme Cu/Zn-SOD, as well as pyruvate utilization in bovine morulae and blastocysts developed in vivo. Heifers were fed a daily ration of either grass silage and a citrus-beet pulp-based concentrate or grass silage and a barley-based concentrate for 116 days, both at 3 kg per day or ad libitum. In embryos derived from heifers fed the pulp-based diets, the relative abundances of the transcripts were not affected by either day of collection or quantity of diet. In embryos derived from heifers fed the barley-based diets, the relative abundances of the Na/K-ATPase transcripts were also not changed by these main effects, while the relative abundances of the Cu/Zn-SOD transcripts were affected by day of collection and by the quantity of diet. Pyruvate metabolism was affected by day of collection, and was significantly increased in day 8 embryos compared with day 7 and day 6 embryos. Diet quantity did not affect pyruvate utilization, whereas diet type did increase pyruvate metabolism in the barley group when compared with the pulp group. The results of this study show for the first time that molecular and metabolic variations may exist in embryos derived in vivo and developed in donor heifers on nutritional regimens differing in type and quantity. Differences in embryos collected on different developmental days may be attributed to varying cell numbers. Alterations in the relative abundances of the Cu/Zn-SOD transcripts and pyruvate metabolism caused by the quantity of diet fed to the donor animal were likely to have been due to alterations in metabolic end products that accumulate in reproductive tract fluids, whereas differences in embryonic metabolism caused by type of diet are related to the composition of the diet. These findings characterize embryos produced in vivo at the molecular level, indicating that the molecular markers used in the present study can differentiate between populations of embryos produced under different nutritional regimens and determine conditions conductive to the production of good quality embryos.
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PMID:Effects of superovulated heifer diet type and quantity on relative mRNA abundances and pyruvate metabolism in recovered embryos. 1079 27

Several works have shown the importance of the creatine kinase (CK) system for cardiac energetics and Ca2+ homeostasis. Nevertheless, CK-deficient mice have cardiac function close to normal, at least under conditions of low or moderate workload. To characterize possible adaptive changes of the sarcoplasmic reticulum (SR) and potential role of glycolytic support in cardiac contractility we used the skinned fibre technique to study properties of the SR and myofibrils, in control and muscle-type homodimer (MM-/mitochondrial-CK)-deficient mice. In control fibres, SR Ca2+ loading with ATP and phosphocreatine (solution PL) was significantly better than loading with ATP alone (solution AL), as determined by analysis of caffeine-induced tension transients. Loading in the presence of ATP and glycolytic intermediates (solution GL) was not significantly different from solution PL. These data indicate that Ca2+ uptake by the SR in situ depends on a local ATP:ADP ratio that is controlled by both CK and glycolytic enzymes. In CK-deficient mice, Ca2+ loading was impaired in solution PL due to the absence of CK. In solution GL, loading was significantly increased, such that calculated Ca2+ release parameters were normalized to those in control fibres in solution PL. In CK-deficient mice, fibre kinetic parameters of tension recovery were impaired after quick stretch in solution PL and were not improved in solution GL. These results show that in CK-deficient mice, at least under basal conditions, glycolysis can replace the CK system in fueling the SR Ca2+ ATPase, but not the myosin ATPase, and may in part explain the limited phenotypic alterations seen in the hearts of these mice.
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PMID:Glycolysis supports calcium uptake by the sarcoplasmic reticulum in skinned ventricular fibres of mice deficient in mitochondrial and cytosolic creatine kinase. 1088 44

Both FliH and the ATPase FliI are cytoplasmic components of the Salmonella type III flagellar export apparatus. Dominance and inhibition data have suggested that the N-terminus of FliI interacts with FliH and that this interaction is important for the ATPase function of the C-terminal domain of FliI. N-terminally histidine-tagged, wild-type FliI retarded untagged FliH in a Ni-NTA affinity chromatography assay, as did N-His-tagged versions of FliI carrying catalytic mutations. In contrast, N-His-tagged FliI carrying the double mutation R7C/L12P did not, further indicating that the N-terminus of FliI is responsible for interaction with FliH. Native agarose gel electrophoresis confirmed that FliH and FliI form a complex. Analytical gel filtration with in-line multiangle light scattering indicated that FliH alone forms a dimer, FliI alone remains as a monomer, and FliH and FliI together form a (FliH)2FliI complex. Ni-NTA affinity chromatography using N-His-tagged FliH and a large excess of untagged FliH confirmed that FliH forms a homodimer. The ATPase activity of the FliH-FliI complex was about 10-fold lower than that of FliI alone; the presence or absence of ATP did not affect the formation of the complex. We propose that FliH functions as a negative regulator to prevent FliI from hydrolysing ATP until the flagellar export apparatus is competent to link this hydrolysis to the translocation of export substrates across the plane of the cytoplasmic membrane into the lumen of the nascent flagellar structure.
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PMID:FliH, a soluble component of the type III flagellar export apparatus of Salmonella, forms a complex with FliI and inhibits its ATPase activity. 1099 79

Copper (Cu) is an essential trace element and constitutes the active center of the redox Cu enzymes such as Cu, Zn-superoxide dismutase (Cu, Zn-SOD), ceruloplasmin and cytochrome c oxidase. Among hereditary diseases due to a defect in the metabolism of Cu, Menkes disease (caused by a Cu deficiency) and Wilson disease (caused by the excessive accumulation of Cu) have been shown to be caused by the mutation of genes encoding Cu-binding ATPase for the efflux of Cu, ATP7A and ATP7B, respectively. Following the identification of these causative genes, intracellular Cu transporters (Cu chaperones) specific for the Golgi apparatus, mitochondria and Cu, Zn-SOD were discovered, and these findings have facilitated the study of the underlying mechanisms of the biological regulation of Cu. Apart from these physiological and biochemical studies, toxicological studies have elucidated the underlying mechanisms of the occurrence of acute hepatitis caused by the accumulation of Cu accumulating in the liver of an animal model for Wilson disease, LEC rats. In these toxicological studies, two biological aspects of metallothionein (MT), i.e., antioxidant and prooxidant depending on the Cu/Zn ratio in Cu-containing MT have been proposed. The present article overviews the recent findings on the biological regulation of Cu and on the toxicological aspect of Cu. It is known that Cu forms a stable ternary complex with molybdenum and sulfur under reductive conditions in the body. On the basis of this observation, tetrathiomolybdate (TTM) has been applied to remove Cu from the liver of Long-Evans rats with a cinnamon-like coat color (LEC) rats. Precise mechanisms underlying the complex formation between Cu bound to MT and TTM were presented, and an appropriate protocol for the chelation therapy was also proposed together with the mechanisms underlying the occurrence of side-effects.
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PMID:[Biological regulation of copper and selective removal of copper: therapy for Wilson disease and its molecular mechanism]. 1108 2

RNA triphosphatase catalyzes the first step in mRNA cap formation which entails the cleavage of the beta-gamma phosphoanhydride bond of triphosphate-terminated RNA to yield a diphosphate end that is then capped with GMP by RNA guanylyltransferase. Here we characterize a 303 amino acid RNA triphosphatase (Pct1p) encoded by the fission yeast SCHIZOSACCHAROMYCES: pombe. Pct1p hydrolyzes the gamma phosphate of triphosphate-terminated poly(A) in the presence of magnesium. Pct1p also hydrolyzes ATP to ADP and P(i) in the presence of manganese or cobalt (K(m) = 19 microM ATP; k(cat) = 67 s(-1)). Hydrolysis of 1 mM ATP is inhibited with increasing potency by inorganic phosphate (I(0.5) = 1 mM), pyrophosphate (I(0.5) = 0.4 mM) and tripolyphosphate (I(0.5) = 30 microM). Velocity sedimentation indicates that Pct1p is a homodimer. Pct1p is biochemically and structurally similar to the catalytic domain of Saccharomyces cerevisiae RNA triphosphatase Cet1p. Mechanistic conservation between Pct1p and Cet1p is underscored by a mutational analysis of the putative metal-binding site of Pct1p. Pct1p is functional in vivo in S.cerevisiae in lieu of Cet1p, provided that it is coexpressed with the S.pombe guanylyltransferase. Pct1p and other yeast RNA triphosphatases are completely unrelated, mechanistically and structurally, to the metazoan RNA triphosphatases, suggesting an abrupt evolutionary divergence of the capping apparatus during the transition from fungal to metazoan species.
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PMID:Characterization of Schizosaccharomyces pombe RNA triphosphatase. 1113 8

In Salmonella typhimurium, formation of the cobalt-carbon bond in the biosynthetic pathway for adenosylcobalamin is catalyzed by the product of the cobA gene which encodes a protein of 196 amino acid residues. This enzyme is an ATP:co(I)rrinoid adenosyltransferase which transfers an adenosyl moiety from MgATP to a broad range of co(I)rrinoid substrates that are believed to include cobinamide, its precursor cobyric acid and probably others as yet unidentified, and hydroxocobalamin. Three X-ray structures of CobA are reported here: its substrate-free form, a complex of CobA with MgATP, and a ternary complex of CobA with MgATP and hydroxycobalamin to 2.1, 1.8, and 2.1 A resolution, respectively. These structures show that the enzyme is a homodimer. In the apo structure, the polypeptide chain extends from Arg(28) to Lys(181) and consists of an alpha/beta structure built from a six-stranded parallel beta-sheet with strand order 324516. The topology of this fold is very similar to that seen in RecA protein, helicase domain, F(1)ATPase, and adenosylcobinamide kinase/adenosylcobinamide guanylyltransferase where a P-loop is located at the end of the first strand. Strikingly, the nucleotide in the MgATP.CobA complex binds to the P-loop of CobA in the opposite orientation compared to all the other nucleotide hydrolases. That is, the gamma-phosphate binds at the location normally occupied by the alpha-phosphate. The unusual orientation of the nucleotide arises because this enzyme transfers an adenosyl group rather than the gamma-phosphate. In the ternary complex, the binding site for hydroxycobalamin is located in a shallow bowl-shaped depression at the C-terminal end of the beta-sheet of one subunit; however, the active site is capped by the N-terminal helix from the symmetry-related subunit that now extends from Gln(7) to Ala(24). The lower ligand of cobalamin is well-ordered and interacts mostly with the N-terminal helix of the symmetry-related subunit. Interestingly, there are few interactions between the protein and the polar side chains of the corrin ring which accounts for the broad specificity of this enzyme. The corrin ring is oriented such that the cobalt atom is located approximately 6.1 A from C5' of the ribose and is beyond the range of nucleophilic attack. This suggests that a conformational change occurs in the ternary complex when Co(III) is reduced to Co(I).
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PMID:Three-dimensional structure of ATP:corrinoid adenosyltransferase from Salmonella typhimurium in its free state, complexed with MgATP, or complexed with hydroxycobalamin and MgATP. 1114 30

Two substances which are products of the isoprenoid pathway, can participate in lipid peroxidation. One is digoxin, which by inhibiting membrane Na(+)-K+ ATPase, causes increase in intracellular Ca2+ and depletion of intracellular Mg2+, both effects contributing to increase in lipid peroxidation. Ubiquinone, another products of the pathway is a powerful membrane antioxidant and its deficiency can also result in defective electron transport and generation of reactive oxygen species. In view of this and also in the light of some preliminary reports on alteration in lipid peroxidation in neuropsychiatric disorders, a study was undertaken on the following aspects in some of these disorders (primary generalised epilepsy, schizophrenia, multiple sclerosis, Parkinson's disease and CNS glioma)--1) concentration of digoxin, ubiquinone, activity of HMG CoA reductase and RBC membrane Na(+)-K+ ATPase 2) activity of enzymes involved in free radical scavenging 3) parameters of lipid peroxidation and 4) antioxidant status. The result obtained indicates an increase in the concentration of digoxin and activity of HMG CoA reductase, decrease in ubiquinone levels and in the activity of membrane Na(+)-K+ ATPase. There is increased lipid peroxidation as evidenced from the increase in the concentration of MDA, conjugated dienes, hydroperoxides and NO with decreased antioxidant protection as indicated by decrease in ubiquinone, vit E and reduced glutathione in schizophrenia, Parkinson's disease and CNS glioma. The activity of enzymes involved in free radical scavenging like SOD, catalase, glutathione peroxidase and glutathione reductase is decreased in the above diseases. However, there is no evidence of any increase in lipid peroxidation in epilepsy or MS. The role of increased operation of the isoprenoid pathway as evidenced by alteration in the concentration of digoxin and ubiquinone in the generation of free radicals and protection against them in these disorders is discussed.
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PMID:Isoprenoid pathway and free radical generation and damage in neuropsychiatric disorders. 1127 6


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