Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pyrophosphate, p-nitrophenyl phosphate and a variety of pyrimidine and purine nucleotides are hydrolyzed by the solubilized membrane-bound enzymes of the brush border plasma membrane of Hymenolepis diminuta. The pH optima (or ranges) for hydrolysis of substrates are 8.0 (pyrophosphate), 8.8 (p-nitrophenyl phosphate), 8.4-8.9 (nucleoside monophosphates), and 7.1-8.1 (nucleoside triphosphates); all substrates, with the exception of nucleoside triphosphates, have a higher affinity for the solubilized enzyme at pH 7.4 than at their optimal pH for hydrolysis. ATP is degraded completely by the enzyme preparation to adenosine and inorganic phosphate, but since neither ADP nor ATP accumulate in the incubation medium it is not known whether ATP hydrolysis involves the sequential hydrolysis of terminal phosphate groups. Isoelectric focusing and various chromatographic procedures (gel permeation, ion-exchange and hydrophobic interaction chromatography) fail to separate the alkaline phosphatase, phosphodiesterase, 5'-nucleotidase, adenosine triphosphatase and ribonuclease activities associated with the solubilized membrane preparation. Additionally, inhibitor studies indicate that only a single enzyme with low substrate specificity is involved in the hydrolysis of nucleotides, p-nitrophenyl phosphate, pyrophosphate and hexose phosphate esters. Purines and pyrimidines and their nucleosides interact with the active site, and in some instances activity of the enzyme is stimulated by an unknown mechanism.
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PMID:Nucleotide hydrolysis by solubilized membrane-bound enzymes of the brush border plasma membrane of Hymenolepis diminuta. 613 88

Praziquantel (PZ) at concentrations down to 5 x 10(-8) M induced a rapid contraction of Hymenolepis diminuta musculature. This effect was accompanied by a strong inhibition of 45Ca2+ incorporation which showed some dependence on Ca2+ concentration. Ca2+ efflux experiments showed that PZ markedly stimulated the release of Ca2+ from tapeworms preloaded with 45Ca2+, with the effluxed Ca2+ being derived from a small fast pool and a larger slow pool. This stimulatory effect appeared., like PZ-induced muscle contraction, to be independent of external Ca2+. By carrying out 45Ca2+ exchange experiments under near equilibrium conditions and atomic absorption spectroscopy it could be demonstrated that PZ resulted in a net excretion of endogenous Ca2+. In PZ-induced contracted worms adenylate nucleotide levels and the adenylate energy charge were not significantly different from those of untreated control worms. Also, PZ had no effect on Ca2+-stimulated ATPase activity of the tapeworm's tegumental brush border. Nor did the drug alter the activities of Ca2+-ATPases in whole homogenates of worms or mitochondria, microsomal or soluble fractions. Although the mechanism of PZ-induced changes in Ca2+ transport was not elucidated, it is suggested that the sustained release of endogenous Ca2+ may affect the sequence of excitation-contraction coupling and that such interference may cause the observed massive contraction of the tapeworm's musculature.
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PMID:The effect of praziquantel on calcium in Hymenolepis diminuta. 621 63

Preparations of isolated brush border plasma membrane of Hymenolepis diminuta and H. microstoma possess the following enzymatic activities: alkaline phosphohydrolase (E.C. 3.1.3.1); Type I phosphodiesterase (E.E. 3.1.4.1); ribonuclease (E.C. 3.1.4.22); adenosine triphosphatase (E.C. 3.6.1.3); and 5'-nucleotidase (E.C. 3.1.3.5). The following enzymatic activities could not be demonstrated in either membrane preparation: Type II phosphodiesterase (E.C. 3.1.4.18); cyclic adenosine-3', 5'-monophosphate phosphodiesterase (E.C. 3.1.4.17); leucine aminopeptidase (E.C. 3.4.11.1); maltase (alpha-glucosidase; E.C. 3.2.1.20); and lactase (beta-galactosidase; E.C. 3.2.1.23). These data generally agree with those of previous studies in which similar membrane-bound enzymes were demonstrated in intact (living) worms.
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PMID:A comparison of membrane-bound enzymes of the isolated brush border plasma membranes of the cestodes of Hymenolepis diminuta and H. microstoma. 628 Jan 22

During growth and maturation of the tapeworm, Hymenolepis diminuta, significant decreases occur in the brush border membrane-bound alkaline phosphatase, phosphodiesterase, 5'-nucleotidase, adenosine triphosphatase and ribonuclease activities. These decreases are accompanied by qualitative and quantitative changes in the polypeptide profiles of the brush border membrane fraction. Gradients of enzymatic activities and polypeptide profiles are also demonstrable when mature tapeworms are cut into pieces and the brush border membrane of each piece analyzed individually. In fully developed tapeworms the enzymatic activities and polypeptide profiles of membrane preparations reflect mainly the contributions of the more mature proglottids; these proglottids constitute most of the tapeworm biomass. The most anterior sections of these fully developed worms are biochemically similar to young, developing worms.
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PMID:Alterations in brush border membrane proteins and membrane-bound enzymes of the tapeworm, Hymenolepis diminuta, during development in the definitive host. 663 65

Ca2+ and Mg2+ caused a concentration-dependent activation of ATP hydrolysis by mitochondrial membranes of Hymenolepis diminuta, a rat intestinal cestode. Ca2+ was the more potent, but Mg2+ the more effective. The Lineweaver-Burk plot yielded Km and Vmax values of 1.15 nM and 217.4 nmol Pi min-1 mg-1 protein for Ca(2+)-dependent activity, and 1.86 mM and 333.3 nmol Pi min-1 mg-1 protein for Mg(2+)-dependent activity, respectively. Neither Na+ nor K+, nor a combination of the two cations, induced the hydrolysis of ATP. Ouabain, a specific inhibitor of Na+/K+ ATPase, did not affect the rate of ATP hydrolysis induced by Mg2+ alone or in combination with Na+ or K+. The membrane-bound enzyme was not affected by neuraminidase and concanavalin A. Ca2+ and Mg2+ also induced appreciable hydrolysis of other nucleoside triphosphates by the membranes. Some known anthelmintics, e.g. niclosamide, praziquantel and mebendazole, had no effect on ATPase activities. In addition to other compounds including respiratory inhibitors and uncouplers of phosphorylation, ruthenium red, which blocks Ca2+ influx into the cestode mitochondria, had no influence on the rate of ATP hydrolysis induced by the cations. Triton X-100 was found most suitable for solubilization of both activities. The differences between cestode ATPase and its mammalian counterpart have been discussed.
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PMID:Ca2+/Mg(2+)-dependent ATPase activity in Hymenolepis diminuta mitochondria. 767 97

Beetles infected with metacestodes of the rat tapeworm, Hymenolepis diminuta, exhibit reduced fecundity, due to alterations in vitellogenesis. Follicle cell patency is retarded and inefficient vitellogenin uptake ensues. Here, we have reassessed patency and its stimulation by JH III at day 3 post-infection, when the most detrimental changes are observed in other ovarian processes. In Rhodnius prolixus, patency is believed to be brought about by the action of a JH-dependent membrane-bound Na(+)/K(+) ATPase (EC 3.6.1.3); however, this had not been established in Tenebrio molitor. Therefore, the properties of the enzyme, with respect to optimal assay conditions and juvenile hormone dependency, are reported. Maximal stimulation occurred between 50 and 500 nM JH III, a range over which greatest increases in patency were also observed. In infected insects, a 35% reduction in Na(+)/K(+) ATPase activity was noted, but exposure to 50 nM JH III is sufficient for stimulation to a specific activity 89% that of JH-treated controls. In a similar fashion, patency in infected insects is reduced, but can be 'rescued' by 50 nM JH III. Moreover, in the absence of exogenous hormone, patency in infected beetles can be elevated to control levels after in vitro culture (6 h), with exchange of medium every 2 h. The possibility that such reversible decreases in enzyme activity and patency are caused by a JH binding inhibitor molecule is discussed. Copyright 1997 Elsevier Science Ltd. All rights reserved
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PMID:The Interplay between Patency, Microsomal Na(+)/K(+) ATPase Activity and Juvenile Hormone, in Tenebrio molitor Parasitized by Hymenolepsis diminuta. 1276 95

Hymenolepis diminuta mitochondria catalyze nonenergy-linked and energy-linked NADH-->NADP(+) transhydrogenations, with the latter driven by electron-transport dependent NADH oxidation (electron transport-driven, ETD) or ATP hydrolysis (ATP-driven, ATPD). Using submitochondrial particles, NADH-->NADP(+) transhydrogenations were characterized further. ETD and ATPD reactions were enhanced by bovine serum albumin (BSA) and were inhibited by N,N'-dicyclohexylcarbodiimide (DCCD), carbonyl cyanide 3-chlorophenylhydrazone (CCCP), carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP), and niclosamide. The nonenergy-linked reaction was unaffected by these additives. Except for DCCD inhibition of the ATPD reaction, BSA mitigated inhibitor effects on energy-linked activities. BSA enhanced NADH oxidase (but not ATPase) activity. Although DCCD inhibited NADH oxidase and ATPase, BSA only lessened oxidase inhibition. With protonophores, an increase in NADH oxidase (but not ATPase) activity was suggested. Oxidase inhibition by rotenone was unaffected by BSA. The ATP-hydrolyzed/NADPH-formed for the ATPD reaction was almost unity. A model for H. diminuta energy-linked transhydrogenation is presented.
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PMID:Catalysis of NADH-->NADP+ transhydrogenation by adult Hymenolepis diminuta mitochondria. 1632 69