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 synthesis of the free radical gas nitric oxide (NO) is catalyzed by the enzyme NO synthase (NOS). NOS converts arginine and molecular oxygen to NO and citrulline in a reaction that requires NADPH, FAD, FMN, and tetrahydrobiopterin as cofactors. Three types of NOS have been identified by molecular cloning. The activity of the constitutively expressed neuronal NOS (nNOS) and endothelial NOS (eNOS) is Ca(2+)/calmodulin-dependent, whereas that the inducible NOS (iNOS) is Ca(2+)-insensitive. The predominant NOS isoform in skeletal muscle is nNOS. It is present at the sarcolemma of both extra- and intrafusal muscle fibers. An accentuated accumulation of nNOS is found in the endplate area. This strict sarcolemmal localization of nNOS is due its association with the dystrophin-glycoprotein complex, which is mediated by the syntrophins. The activity of nNOS in skeletal muscle is regulated by developmental, myogenic, and neurogenic influences. NO exerts several distinct effects on various aspects of skeletal muscle function, such as excitation-contraction coupling, mitochondrial energy production, glucose metabolism, and autoregulation of blood flow. Inside the striated muscle fibers, NO interacts directly with several classes of proteins, such as soluble guanylate cyclase, ryanodine receptor, sarcoplasmic reticulum Ca(2+)-ATPase, glyceraldehyde-3-phosphate dehydrogenase, and mitochondrial respiratory chain complexes, as well as radical oxygen species. In addition, NO produced and released by contracting muscle fibers diffuses to nearby arterioles where it acts to inhibit reflex sympathetic vasoconstriction.
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PMID:NO message from muscle. 1174 89

The cardiac sarcoplasmic reticulum calcium-ATPase (SERCA2a), Na+/Ca2+ exchanger (NCX1), and ryanodine receptor (RyR2) are proteins involved in the regulation of myocyte calcium. We tested whether exercise training (ET) alters those proteins during development of chronic heart failure (CHF). Ten dogs were chronically instrumented to permit hemodynamic measurements. Five dogs underwent 4 wk of cardiac pacing (210 beats/min for 3 wk and 240 beats/min for the 4th wk), whereas five dogs underwent the same pacing regimen plus daily ET (5.1 +/- 0.3 km/h, 2 h/day). Paced animals developed CHF characterized by hemodynamic abnormalities and reduced ejection fraction. ET preserved resting hemodynamics and ejection fraction. Left ventricular samples were obtained from all dogs and another five normal dogs for mRNA (Northern analysis, band intensities normalized to glyceraldehyde-3-phosphate dehydrogenase) and protein level (Western analysis, band intensities normalized to tubulin) measurements. In failing hearts, SERCA2a was decreased by 33% (P < 0.05) and 65% (P < 0.05) in mRNA and protein level, respectively, compared with normal hearts; there was only an 8.6% reduction in mRNA and a 32% reduction in protein in exercised animals (P < 0.05 from CHF). mRNA expression of NCX1 increased by 44% in paced-only dogs compared with normal (P < 0.05) but only by 22% in trained dogs (P < 0.05 vs. CHF); protein level of NCX1 was elevated in paced-only dogs (71%, P < 0.05) but partially normalized by ET (33%, P < 0.05 from CHF). RyR2 was not altered in any of the dogs. In conclusion, long-term ET may ameliorate cardiac deterioration during development of CHF, in part via normalization of myocardial calcium-handling proteins.
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PMID:Exercise training normalizes altered calcium-handling proteins during development of heart failure. 1189 19

A vast number of experimental and clinical studies implicates oxygen-derived free radicals (especially, superoxide and the hydroxyl radical) and high energy oxidants (such as peroxynitrite) as mediators of acute and chronic inflammation. The purpose of this review is to summarize the pharmacological actions of melatonin in acute and chronic inflammation. Reactive oxygen species can modulate a wide range of toxic oxidative reactions. These include initiation of lipid peroxidation, direct inhibition of mitochondrial respiratory chain enzymes, inactivation of glyceraldehyde-3-phosphate dehydrogenase, inhibition of membrane sodium/potassium ATPase activity, inactivation of membrane sodium channels, and other oxidative modifications of proteins. Reactive oxygen species (e.g., superoxide, peroxynitrite, hydrogen peroxide and hydroxyl radical) are all potential reactants capable of initiating DNA single strand breakage, with subsequent activation of the nuclear enzyme poly (ADP ribose) synthetase (PARS), leading to eventual severe energy depletion of the cells, and necrotic-type cell death. These toxic reactions are likely to play a role in the pathophysiology of inflammation. Melatonin has been shown to possess both in vitro and in vivo important antioxidant activities as well as to inhibit the activation of poly (ADP ribose) synthetase. A large number of experimental studies have documented that melatonin exerts important anti-inflammatory actions.
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PMID:Pharmacological actions of melatonin in acute and chronic inflammation. 1189 98

Oxidative stress results from an oxidant/antioxidant imbalance: an excess of oxidants relative to the antioxidant capacity. Recent evidence strongly suggests that oxidant stress plays a major role in several aspects of ischemia and reperfusion. Immunohistochemical and biochemical evidence demonstrate the significant role of reactive oxygen species, in particular superoxide and its reaction product peroxynitrite, formed by the interaction of superoxide and nitric oxide, in endothelial and tissue injury associated with ischemia and reperfusion. Endothelial cell damage, neutrophil activation and infiltration into tissues, lipid peroxidation, direct inhibition of mitochondrial respiratory chain enzymes, inactivation of glyceraldehyde-3-phosphate dehydrogenase, inhibition of membrane sodium/potassium ATPase activity, inactivation of membrane sodium channels and other oxidative protein modifications contribute to the cytotoxic effect of superoxide and peroxynitrite. In addition, superoxide and peroxynitrite trigger DNA strand breakage, with subsequent activation of the nuclear enzyme poly-ADP ribosyl synthetase, a pathway which contributes to the cellular injury in ischemia and reperfusion. In vivo, removal of superoxide (and thus of peroxynitrite) by superoxide dismutase mimetics (SODm), which mimic the catalytic activity of the human superoxide dismutase enzymes, prevent the cellular energetic failure and tissue damage associated with ischemia and reperfusion and exert an overall beneficial effect in this situation. The role(s) of superoxide and the potential utility of SODm will be discussed in this review.
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PMID:Superoxide, superoxide dismutase and ischemic injury. 1213 8

The understanding of control of metabolic processes requires quantitative studies of the importance of the different enzymatic steps for the magnitude of metabolic fluxes and metabolite concentrations. An important element in such studies is the modulation of enzyme activities in small steps above and below the wild-type level. We review a genetic approach that is well suited for both Metabolic Optimization and Metabolic Control Analysis and studies on the importance of a number of glycolytic enzymes for metabolic fluxes in Lactococcus lactis. The glycolytic enzymes phosphofructokinase (PEK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), pyruvate kinase (PYK) and lactate dehydrogenase (LDH) are shown to have no significant control on the glycolytic flux in exponentially growing cells of L. lactis MG1363. Introduction of an uncoupled ATPase activity results in uncoupling of glycolysis from biomass production. With MG1363 growing in defined medium supplemented with glucose, the ATP demanding processes do not have a significant control on the glycolytic flux; it appears that glycolysis is running at maximal rate. It is likely that the flux control is distributed over many enzymes in L. lactis, but it cannot yet be excluded that one of the remaining glycolytic steps is a rate-limiting step for the glycolytic flux.
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PMID:Experimental determination of control of glycolysis in Lactococcus lactis. 1236 90

In this study, we show that reactive oxygen species production induced by tumour necrosis factor alpha (TNF-alpha) in L929 cells was associated with a decrease in the steady-state mRNA levels of the mitochondrial transcript ATPase 6-8. Simultaneously, the transcript levels of two nuclear-encoded glycolytic enzymes, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and phosphofructokinase, were increased. These changes were associated with decreased protein levels of the ATPase subunit a (encoded by the mitochondrial ATPase 6 gene) and cytochrome c oxidase subunit II, and increased protein levels of phosphofructokinase. Since TNF-alpha had no effect on the amount of mitochondrial DNA, the results suggested that TNF-alpha acted at the transcriptional and/or post-transcriptional level. Reactive oxygen species scavengers, such as butylated hydroxianisole and butylated hydroxytoluene, blocked the production of free radicals, prevented the down-regulation of ATPase 6-8 transcripts, preserved the protein levels of ATPase subunit a and cytochrome c oxidase subunit II, and attenuated the cytotoxic response to TNF-alpha, indicating a direct link between these two phenomena.
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PMID:Reactive oxygen species mediate the down-regulation of mitochondrial transcripts and proteins by tumour necrosis factor-alpha in L929 cells. 1247 Feb 98

Oxidative stress results from an oxidant/antioxidant imbalance, an excess of oxidants, or a depletion of antioxidants. A considerable body of recent evidence suggests that oxidative stress and exaggerated production of reactive oxygen species play a major role in several aspects of septic shock and ischemia and reperfusion. Initiation of lipid peroxidation, direct inhibition of mitochondrial respiratory chain enzymes, inactivation of glyceraldehyde-3-phosphate dehydrogenase, inhibition of membrane Na /K adenosine triphosphatase activity, inactivation of membrane sodium channels, and other oxidative protein modifications contribute to the cytotoxic effect of reactive oxygen species. In addition, reactive oxygen species are potent triggers of DNA strand breakage, with subsequent activation of the nuclear enzyme poly-adenosine 5'-diphosphate ribosyl synthetase, and eventual severe energy depletion of the cells. Pharmacologic evidence suggests that the peroxynitrite-poly-adenosine 5'-diphosphate ribosyl polymerase pathway contributes to the cellular injury in shock and endothelial injury. Treatment with superoxide dismutase mimetics, which selectively mimic the catalytic activity of the human superoxide dismutase enzymes, has been shown to prevent the cellular energetic failure associated with shock and ischemia-reperfusion and to prevent tissue damage associated with these conditions. In this article, we will briefly review the role of superoxide in septic shock and ischemia-reperfusion injury. We hope to present evidence to support the potential development of superoxide dismutase mimetics as novel and effective agents in the area of critical care medicine.
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PMID:Therapeutic potential of superoxide dismutase mimetics as therapeutic agents in critical care medicine. 1254 74

Protein phosphatases play a major role in the regulation of L-type calcium current (I(Ca)) in heart cells. We previously showed developmental differences in the effects of inhibitors of protein phosphatases (PP's) on the modulation of I(Ca), with greater stimulatory effects on I(Ca) observed in newborn than in adult ventricular cells. We hypothesized that this developmental difference might be due to greater expression and levels of PP 1 and PP 2A in newborn than in adult ventricular cells. We thus determined the mRNA expression of alpha and beta subunits of PP 1 and the a subunit of PP 2A in adult and newborn rabbit ventricles and levels of PP 1 and PP 2A in total homogenates, particulate membranes, and in soluble fraction prepared from isolated ventricular myocytes from adult and newborn rabbits. RT-PCR analysis demonstrated the presence of mRNA of these subunits of PP's in both newborn and adult ventricles. Northern blot analysis using 32P labeled cDNA probes specific for PP 1alpha, PP 1beta and PP 2Aalpha showed that the expression of steady state mRNA levels for PP 1alpha, PP 1beta and PP 2Aalpha were much higher in newborn compared to adult rabbit ventricles. mRNA for glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and for sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) in rabbit ventricles were measured as controls. GAPDH did not show significant developmental changes while mRNA for SERCA was higher in adult compared to newborns. Western blot analysis showed that PP 1 and PP 2A protein levels were also much higher in newborn compared to adult rabbit ventricular cells. Immunoblot analysis in particulate membranes and soluble fraction showed that PP1 was mainly membrane bound while PP 2 was present only in soluble fraction. These findings suggest that the two major protein phosphatases (PP 1 and PP 2A) in heart are expressed at much higher levels in newborn and decline to lower levels in adult ventricular myocytes. The presence of high levels of PP's and particularly PP 1 in newborn cells may be responsible for the greater dependence of newborn cells on the inhibition of PP as a mechanism of action of beta-agonist isoproterenol on I(Ca).
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PMID:Expression of protein phosphatases during postnatal development of rabbit heart. 1270 48

The nature of oxidative damage to Saccharomyces cerevisiae caused by levels of HOCl that inhibit cell replication was explored with the intent of identifying the loci of lethal lesions. Functions of cytosolic enzymes and organelles that are highly sensitive to inactivation by HOCl, including aldolase, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and the mitochondrion, were only marginally affected by exposure of the yeast to levels of HOCl that completely inhibited colony formation. Loss of function in membrane-localized proteins, including the hexose transporters and PMA1 H(+)-ATPase, which is the primary proton pump located within the S. cerevisiae plasma membrane, was also marginal and K(+) leak rates to the extracellular medium increased only slowly with exposure to increasing amounts of HOCl, indicating that the plasma membrane retained its intrinsic impermeability to ions and metabolites. Adenylate phosphorylation levels in fermenting yeast declined in parallel with viability; however, yeast grown on respiratory substrates maintained near-normal phosphorylation levels at HOCl doses several-fold greater than that required for killing. This overall pattern of cellular response to HOCl differs markedly from that previously reported for bacteria, which appear to be killed by inhibition of plasma membrane proteins involved in energy transduction. The absence of significant loss of function in critical oxidant-sensitive cellular components and retention of ATP-synthesizing capabilities in respiring yeast cells exposed to lethal levels of HOCl suggests that toxicity in this case may arise by programmed cell death.
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PMID:HOCl-mediated cell death and metabolic dysfunction in the yeast Saccharomyces cerevisiae. 1487 79

Multilocus sequence typing (MLST) was used to obtain insights into the genetic relationships between 14 vancomycin-resistant Enterococcus faecium (VREF) isolates from humans (hospitalized patients, 5 strains) and nonhuman sources (meat and poultry, 9 strains) in northern Italy over the period 1993-2001. The typing scheme (Homan et al., 2002, J. Clin. Microb., 40:1963-1971) based on seven housekeeping genes--adk (adenylate kinase), atpA (ATP synthase, alpha subunit), ddl (D-alanine-D-alanine ligase), gyd (glyceraldehyde-3-phosphate dehydrogenase), gdh (glucose-6-phosphate dehydrogenase), purK (phosphoribosylaminoimidazole carboxylase ATPase subunit), and pstS (phosphate ATP-binding cassette transporter)--was used. In the 14 VREF analyzed, the number of unique alleles ranged from 1 (gyd) to 8 (atpA). Isolates from hospitalized patients were defined by the unique allele purK 1. Nine sequence types (STs) were identified. All of the epidemic strains isolated over the period 2000-2001 showed identical or closely related pulsed-field gel electrophoresis (PFGE) patterns and clustered in the same ST78. These strains shared six of the seven alleles with the strain CA20 representative of the 1993-1999 outbreaks, which PFGE indicated as being unrelated to those of the recent outbreaks. MLST confirmed the unrelatedness of human and nonhuman strains already detected by PFGE. All isolates clustered in three main genetic lineages: group A comprised two of the three isolates from meat; group C the human strains of all outbreaks and one poultry strain; and group B four of the five poultry strains and one meat strain. All human strains carried the esp gene and clustered in the C1 sublineage that has been described as having emerged recently worldwide.
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PMID:Vancomycin-resistant Enterococcus faecium isolates causing hospital outbreaks in northern Italy belong to the multilocus sequence typing C1 lineage. 1525 26


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