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)

A chemically reactive ATP analogue, 6-[(3-carboxy-4-nitrophenyl)thio]-9-beta-D-ribofuranosylpurine 5'-triphosphate (Nbs6ITP) has been synthesized. It has the ability to form stable thioether bonds between the 6-position of the purine ring and aliphatic mercapto groups. The nucleotide moiety of the reagent has been covalently bound to agarose, via iminobispropylamine and N-acetyl-homocysteine as space with the purpose of producing an affinity chromatography material. The affinity matrix binds solubilized F1 ATPase from a crude extract of Micrococcus sp. membranes. Afterwards the enzyme can be selectively eluted from the column at a defined ATP concentration. This method is superior to the conventional purification with respect to speed and convenince of the preparation. The affinity chromatography leads in a one-step process to the same purity to enzyme, substituting several steps of the conventional method. In addition, the affinity matrix was used for binding studies. Although the presence of Mg2+ ions is a prerequisite for the hydrolysis of nucleoside 5'-triphosphates, evidence is presented indicating that the binding of the nucleoside triphosphates to highly purified F1 ATPase from Micrococcus sp. appears not to be influenced by Mg2+ ion concentrations so far examined.
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PMID:Membrane-bound F1 ATPase from Micrococcus Sp. ATCC 398E. Purificationa and characterization ny affinity chromatography. 13 91

The key to symptomatology in uremia is nitrogen retention leading to amidination and transmidination of a variety of substrates. The product of this activity is a series of guanidino acids which are methyl receptors converting S-adenosylmethionine to adenosine and homocysteine. Adenosine is a potent inhibitor of the enzyme ATPase and, in this way, contributes to the anemia, the bleeding diathesis and the CNS symptoms of uremia. Homocysteine is an inhibitor of pyridoxal phosphate-induced reactions and contributes to the angiitis and thromboembolism so unexpectedly encountered in chronic uremia.
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PMID:Alternate reasons for atherogenesis in uremia. 15 May 96

We have investigated in intact chromaffin secretory vesicles the kinetics, specificity, and mechanism of intragranular ascorbic acid regeneration by extragranular ascorbic acid. The apparent Km of internal ascorbic acid regeneration for external ascorbic acid was 280 microM by Lineweaver-Burk analysis and 287 microM by Eadie-Hofstee analysis. Intragranular ascorbic acid regeneration was specifically mediated by extragranular ascorbic acid or its isomer isoascorbic acid; the reducing agents glutathione, thiourea, homocysteine, NADH, and NADPH did not support regeneration. The structural analog D-glucose did not inhibit regeneration by external ascorbic acid, suggesting specificity at the membrane site of electron transfer. The driving force for regeneration of intragranular ascorbic acid was independent of membrane potential, absolute intragranular and extragranular pH, and ATPase activity, but might be coupled to the pH difference across the chromaffin granule membrane. Since the apparent Km of regeneration was approximately 10-fold below the cytosolic concentration of ascorbic acid, the reaction may proceed at Vmax in situ.
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PMID:Ascorbic acid regeneration in chromaffin granules. In situ kinetics. 182 97

Heart sarcolemma has been shown to possess three catalytic sites (I, II and III) for methyl transferase activity (Panagia V, Ganguly PK and Dhalla NS. Biochim Biophys Acta 792:245-253, 1984). In this study we examined the effect of phosphatidylethanolamine N-methylation on ATP-independent Ca2+ binding and ATPase activities in isolated rat heart sarcolemma. Both low affinity (1.25 mM Ca2+) and high affinity (50 microM Ca2+) Ca2+ binding activities were decreased following incubation of sarcolemmal membranes with AdoMet under optimal conditions for site II and III. Similarly, Ca2+ ATPase activities measured at 1.25 mM and 4 mM Ca2+ were depressed by phospholipid N-methylation. S-adenosyl homocysteine, a specific inhibitor of phospholipid N-methylation, prevented the depression of low affinity Ca2+ binding and Ca2+ ATPase activities, whereas the methylation-induced effect on the high affinity Ca2+ binding was not influenced by this agent. Pretreatment of sarcolemma with methyl acetimidate hydrochloride, an amino group blocking agent, also prevented the methylation-induced inhibition of both Ca2+ binding and Ca2+ ATPase. A further decrease in Ca2+ binding and Ca2+ ATPase activities together with a marked increase in the intramembranal level of PC was seen when membranes were methylated under the site III conditions in the presence of phosphatidyldimethylethanolamine as exogenous substrate. There was no effect of phospholipid methylation on sarcolemmal Na+-K+ ATPase and Mg2+ ATPase activities. These results indicate a role of phospholipid N-methylation in the regulation of sarcolemmal Ca2+ ATPase and low affinity ATP-independent Ca2+ binding.
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PMID:Decreased Ca2+-binding and Ca2+-ATPase activities in heart sarcolemma upon phospholipid methylation. 284 56

Protein carboxylmethylase (S-adenosyl-L-methionine:protein O-methyltransferase, EC 2.1.1.24.) is believed to be involved in the regulation of sperm motility. To test this hypothesis, we investigated the effects of erythro-9-[3-(2-hydroxynonyl)]adenine (EHNA) which, in combination with adenosine and homocysteine thiolactone, inhibits protein carboxylmethylase activity in monocytes. This group of compounds inhibited sea urchin sperm motility. Unexpectedly, EHNA alone inhibited the motility., This observation was confirmed in intact spermatozoa from rats, rabbits, and humans. EHNA also inhibited the motility of demembranated, reactivated sea urchin and rat spermatozoa from which protein carboxylmethylase had been extracted. In these preparations, motility was restored by ATP. These observations suggested that EHNA arrests sperm motility by inhibiting the axonemal dynein ATPase on which motility depends. Kinetic analysis demonstrated that EHNA produced mixed inhibition of both the axonemal ATPase and the partially purified dynein 1 from sea urchin sperm tails, as well as the axonemal ATPase of rat sperm tails. These observations also provide evidence for the similarity of the active site of the dynein ATPase in sea urchin and rat spermatozoa.
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PMID:erythro-9-[3-(2-Hydroxynonyl)]adenine is an inhibitor of sperm motility that blocks dynein ATPase and protein carboxylmethylase activities. 645 42

Transposon mutagenesis was employed to isolate the gene(s) related with the biosynthesis of dipeptide antibiotic in Bacillus subtilis PY79 (a prototrophic derivative of the standard 168 strain). The blocked mutants were phenotypically selected from the transposon library by bioassay and the complete loss of biosynthetic ability was verified through ESI-mass spectrometry analysis. Four different bacilysin nonproducer mutants (Bac(-)::Tn10(ori-spc)) were isolated from the transposon library. The genes involved in bacilysin biosynthesis were identified as thyA (thymidilate synthetase), ybgG (unknown; similar to homocysteine methyl transferase) and oppA (oligopeptide permease), respectively. The other blocked gene was yvgW (unknown; similar to heavy metal-transporting ATPase); however, backcross studies did not verify its involvement in bacilysin biosynthesis. This gene, on the other hand, appeared to be necessary for efficient sporulation and transformation. Opp involvement was significant as it suggested that bacilysin biosynthesis is under or a component of the quorum sensing pathway which has been shown to be responsible for the establishment of sporulation, competence development and onset of surfactin biosynthesis. For verification, it was necessary to check the involvement of peptide pheromones (PhrA or PhrC) internalized by the Opp system and response regulator ComA as the essential components of this global control. phrA, phrC and comA deleted mutants of PY79 were thus constructed and the latter two genes were shown to be essential for bacilysin biosynthesis.
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PMID:Tn10 insertional mutations of Bacillus subtilis that block the biosynthesis of bacilysin. 1126 63

The objective of the present study was to investigate the effects of preincubation of hippocampus homogenates in the presence of homocysteine or methionine on Na+, K+-ATPase and Mg2+-ATPase activities in synaptic membranes of rats. Homocysteine significantly inhibited Na+, K+-ATPase activity, whereas methionine had no effect. Mg2+-ATPase activity was not altered by the metabolites. We also evaluated the effect of incubating glutathione, cysteine, dithiothreitol, trolox, superoxide dismutase and GM1 ganglioside alone or incubation with homocysteine on Na+, K+-ATPase activity. Tested compounds did not alter Na+, K+-ATPase and Mg2+-ATPase activities, but except for trolox, prevented the inhibitory effect of homocysteine on Na+, K+-ATPase activity. These results suggest that inhibition of this enzyme activity by homocysteine is possibly mediated by free radicals and may contribute to the neurological dysfunction found in homocystinuric patients.
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PMID:Inhibition of rat brain Na+, K+-ATPase activity induced by homocysteine is probably mediated by oxidative stress. 1187

In the present work, we investigated the kinetics of the inhibition of Na(+), K(+)-ATPase activity caused by homocysteine (Hcy) in rat hippocampus. We also studied the interaction between Hcy and phenylalanine (Phe) and the kinetics of alanine (Ala) reversal of the inhibition of Na(+), K(+)-ATPase caused by Hcy. The apparent K(m) and V(max) of Na(+), K(+)-ATPase for ATP as substrate were 0.55mM and 2.0nmol Pi released per min per mg of protein, respectively. K(i) value was approximately 0.1mM, and the inhibition was of the non-competitive type. The results also showed a competition between Hcy and Phe. Ala per se did not alter this enzyme, but prevented the inhibitory effect caused by Hcy, suggesting a common binding site for these substances. It is proposed that the inhibition of Na(+), K(+)-ATPase by Hcy may be one of the mechanisms related to the neuronal dysfunction observed in human homocystinuria.
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PMID:On the mechanism of the inhibition of Na(+), K(+)-ATPase activity caused by homocysteine. 1203 38

Homocystinuria is an inborn error of sulfur amino acid metabolism characterized predominantly by vascular and nervous system dysfunction. In this study we determined the in vitro effects of homocysteine and methionine, metabolites which accumulate in homocystinuria, on Na+, K+-ATPase, and Mg2+-ATPase activities in synaptic membranes from the hippocampus of rats. The results showed that both metabolites significantly inhibit Na+, K+-ATPase but not Mg2+-ATPase activity at concentrations usually observed in plasma of homocystinuric patients. Furthermore, incubation of hippocampal homogenates with homocysteine also elicited an inhibition of the enzyme activity which was however prevented by the simultaneous addition of cysteine to the medium. In addition, cysteine or methionine per se did not modify the two enzymatic activities. These findings indicate that oxidation of critical groups in the enzyme may possibly be involved in homocysteine inhibitory effect. Moreover, kinetic studies performed to investigate the interaction between homocysteine and methionine on Na+, K+-ATPase inhibition suggested a common site for the two amino acids in the enzyme. Considering the critical role exerted by Na+, K+-ATPase in brain, it is proposed that the inhibition provoked by homocysteine and methionine on the enzyme activity may be possibly related to the brain dysfunction characteristic of homocystinuria.
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PMID:Inhibition of Na+, K+-ATPase activity by the metabolites accumulating in homocystinuria. 1208 40

Hyperhomocysteinemia occurs in homocystinuria, an inherited metabolic disease clinically characterized by thromboembolic episodes and a variable degree of neurological dysfunction whose pathophysiology is poorly known. In this study, we induced elevated levels of homocysteine (Hcy) in blood (500 microM), comparable to those of human homocystinuria, and in brain (60 nmol/g wet tissue) of young rats by injecting subcutaneously homocysteine (0.3-0.6 micromol/g of body weight) twice a day at 8-hr intervals from the 6th to the 28th postpartum day. Controls received saline in the same volumes. Na(+),K(+)-ATPase and Mg(2+)-ATPase activities were determined in the hippocampus of treated Hcy- and saline-treated rats. Chronic administration of Hcy significantly decreased (40%) Na(+),K(+)-ATPase activity but did not alter Mg(2+)-ATPase activity. Considering that Na(+),K(+)-ATPase plays a crucial role in the central nervous system, our results suggest that the brain dysfunction found in homocystinuria may be related to the reduction of brain Na(+),K(+)-ATPase activity.
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PMID:Reduction of Na(+),K(+)-ATPase activity in hippocampus of rats subjected to chemically induced hyperhomocysteinemia. 1251 10


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