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:3.1.3.1 (alkaline phosphatase)
47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The specific activity of adenosine diphosphatase (ADPase) was determined in rat tissue homogenates using a specific radioassay. 14 different tissues were sampled and activity was found in most homogenates examined. The levels ranged from very little activity in the pancreas to high levels in the duodenum and ileum. High levels of ADPase activity found in the gastrointestinal tract could be partially attributed to non-specific alkaline phosphatase. It is concluded that ADPase activity is widely distributed in rat tissues.
...
PMID:Tissue distribution of adenosine diphosphatase activity in the rat. 632 44

Human placental chorioepithelial brush border membrane, which is in direct contact with maternal blood flow, has platelet aggregation inhibiting activity. In the present study, the mechanism of this action has been examined in relation to ADP (adenosine diphosphate) degrading activity and alkaline phosphatase activity of brush border membrane vesicles (BBMV). BBMV prepared from human early and term placental villi, inhibited platelet aggregation induced by ADP. BBMV had potent ADP degrading (ADPase) activity. ADP was quickly degraded by BBMV. ADP degrading activity of BBMV was not so different between early and term placenta. Alkaline phosphatase activity of late placental BBMV was about three times greater than that of early placental BBMV. On the other hand, ADP degrading activity of late placental BBMV was almost the same as that of early placental BBMV. Inhibiting activity of platelet aggregation induced by ADP and ADP degrading activity of BBMV, were not inhibited by levamisole (alkaline phosphatase inhibitor).
...
PMID:Platelet aggregation inhibiting activity of human placental chorioepithelial brush border membrane vesicles--the role of alkaline phosphatase. 806 52

In the present report we describe an apyrase (ATP diphosphohydrolase, EC 3.6.1.5) in rat blood platelets. The enzyme hydrolyses almost identically quite different nucleoside di- and triphosphates. The calcium dependence and pH requirement were the same for the hydrolysis of ATP and ADP and the apparent Km values were similar for both Ca(2+)-ATP and Ca(2+)-ADP as substrates. Ca(2+)-ATP and Ca(2+)-ADP hydrolysis could not be attributed to the combined action of different enzymes because adenylate kinase, inorganic pyrophosphatase and nonspecific phosphatases were not detected under our assay conditions. The Ca(2+)-ATPase and Ca(2+)-ADPase activity was insensitive to ATPase, adenylate kinase and alkaline phosphatase classical inhibitors, thus excluding these enzymes as contaminants. The results demonstrate that rat blood platelets contain an ATP diphosphohydrolase involved in the hydrolysis of ATP and ADP which are vasoactive and platelet active adenine nucleotides.
...
PMID:Characterization of an ATP diphosphohydrolase activity (APYRASE, EC 3.6.1.5) in rat blood platelets. 817 26

Transport of yeast alkaline phosphatase (ALP) to the vacuole depends on the clathrin adaptor-like complex AP-3, but does not depend on proteins necessary for transport through pre-vacuolar endosomes. We have identified ALP sequences that direct sorting into the AP-3-dependent pathway using chimeric proteins containing residues from the ALP cytoplasmic domain fused to sequences from a Golgi-localized membrane protein, guanosine diphosphatase (GDPase). The full-length ALP cytoplasmic domain, or ALP amino acids 1-16 separated from the transmembrane domain by a spacer, directed GDPase chimeric proteins from the Golgi complex to the vacuole via the AP-3 pathway. Mutation of residues Leu13 and Val14 within the ALP cytoplasmic domain prevented AP-3-dependent vacuolar transport of both chimeric proteins and full-length ALP. This Leucine-Valine (LV)-based sorting signal targeted chimeric proteins and native ALP to the vacuole in cells lacking clathrin function. These results identify an LV-based sorting signal in the ALP cytoplasmic domain that directs transport into a clathrin-independent, AP-3-dependent pathway to the vacuole. The similarity of the ALP sorting signal to mammalian dileucine sorting motifs, and the evolutionary conservation of AP-3 subunits, suggests that dileucine-like signals constitute a core element for AP-3-dependent transport to lysosomal compartments in all eukaryotic cells.
...
PMID:A dileucine-like sorting signal directs transport into an AP-3-dependent, clathrin-independent pathway to the yeast vacuole. 956 31

This study investigated the characteristics of ecto-nucleotidases in tissues lining the perilymphatic cavity of the cochlea. The perilymphatic space of the isolated guinea-pig cochlea was maintained with oxygenated artificial perilymph (AP) perfused at a rate of 100 microl/min. Following AP perfusion, either adenosine triphosphate (ATP), adenosine diphosphate (ADP) or adenosine monophosphate (AMP) was introduced into scala tympani, and perfusion arrested for 2 min for substrate incubation with cochlear tissues. Effluent collected from the cochlea was assayed for adenine nucleotide metabolites by reverse-phase high-performance liquid chromatography (RP-HPLC). Extracellular ATP and ADP were rapidly and sequentially hydrolysed to adenosine by Ca2+/Mg2+-dependent and Ca2+/Mg2+-independent enzymatic mechanisms. The degradation of extracellular ATP, ADP and AMP occurred in the presence of intact tissues, as demonstrated by the limited lactate dehydrogenase (LDH) activity (0-2.2%). ATPase activity was not affected by inhibitors of intracellular ATPases (oligomycin, ouabain, N-ethylmaleimide, 100 microM NaN3) and non-specific alkaline phosphatase (beta-glycerophosphate). The hydrolysis of ATP was inhibited by 5 mM NaN3, suramin, ATPgammaS, La3+ and CTP, the hydrolysis of ADP by beta,gamma-imidoATP, and AMP degradation by alpha,beta-methyleneADP. Ecto-ATPase, ecto-ADPase and ecto-5'-nucleotidase followed Michaelis-Menten hyperbolic kinetics, with estimated Km values of 2282 microM, 6619 microM and 881 microM, respectively. Our results indicate the presence of considerable ecto-nucleotidase activity within scala tympani of the cochlea, and support its role as the terminating mechanism for P2 receptor signalling known to occur in the cochlea. A competition plot is consistent with ATP and ADP degradation mediated by the same enzyme (ecto-ADP diphosphohydrolase) with two different catalytic sites.
...
PMID:The pharmacology and kinetics of ecto-nucleotidases in the perilymphatic compartment of the guinea-pig cochlea. 958 Apr 35

Although the submandibular gland of ferret is useful for studying salivary secretory processes which are regulated by nerves and involve myoepithelial activity, little attention has been paid to its parenchymal innervation and myoepithelial arrangements. Therefore, glands obtained postmortem from mature ferrets of both sexes were here examined with the use of light-microscopic histochemical techniques for cholinesterases, phosphatases and phosphorylase, histofluorescence for catecholamines, and milling dyes. Acetylcholinesterase staining was associated with nerve trunks in the interlobular stroma and an extensive intralobular network of nerve fibres, presumably of a cholinergic type, embracing acini and ducts. There were fewer fibres containing fluorescing catecholamines, presumably adrenergic. They were largely associated with acini. Numerous stellate cells with fine branching processes embracing acini, presumably myoepithelial cells, and a few spindle-shaped basal cells, investing striated ducts, were demonstrated on frozen tissue by alkaline phosphatase, but not by adenosine triphosphatase, inosine diphosphatase and phosphorylase. Cells of similar shape and distribution were also demonstrated by staining with milling dyes on fixed tissues, indicating possibly a filamentous constituent conferring mechanical stability and/or contractile ability. Together, these results suggest, firstly, that a cholinergic-type parenchymal innervation is prominent in the submandibular gland of ferret, although many adrenergic nerves are also present, and, secondly that the gland has a very extensive myoepithelial network which is possibly involved in membrane transport, and the support and or contraction of the secretory parenchyma.
...
PMID:Innervation and myoepithelial arrangements in the submandibular salivary gland of ferret investigated by enzyme, catecholamine and filament histochemistry. 1066 82

In the present report the enzymatic properties of an ATP diphosphohydrolase (apyrase, EC 3.6.1.5) in Trichomonas vaginalis were determined. The enzyme hydrolyses purine and pyrimidine nucleoside 5'-di- and 5'-triphosphates in an optimum pH range of 6.0--8.0. It is Ca(2+)-dependent and is insensitive to classical ATPase inhibitors, such as ouabain (1 mM), N-ethylmaleimide (0.1 mM), orthovanadate (0.1 mM) and sodium azide (5 mM). A significant inhibition of ADP hydrolysis (37%) was observed in the presence of 20 mM sodium azide, an inhibitor of ATP diphosphohydrolase. Levamisole, a specific inhibitor of alkaline phosphatase, and P(1), P(5)-di (adenosine 5'-) pentaphosphate, a specific inhibitor of adenylate kinase, did not inhibit the enzyme activity. The enzyme has apparent K(m) (Michaelis Constant) values of 49.2+/-2.8 and 49.9+/-10.4 microM and V(max) (maximum velocity) values of 49.4+/-7.1 and 48.3+/-6.9 nmol of inorganic phosphate x min(-1) x mg of protein(-1) for ATP and ADP, respectively. The parallel behaviour of ATPase and ADPase activities and the competition plot suggest that ATP and ADP hydrolysis occur at the same active site. The presence of an ATP diphosphohydrolase activity in T. vaginalis may be important for the modulation of nucleotide concentration in the extracellular space, protecting the parasite from the cytolytic effects of the nucleotides, mainly ATP.
...
PMID:Characterisation of an ATP diphosphohydrolase (Apyrase, EC 3.6.1.5) activity in Trichomonas vaginalis. 1140 67

The physiological action of extracellular ATP and other nucleotides in the nervous system is controlled by surface-located enzymes (ecto-nucleotidases) of which several families with partially overlapping substrate specificities exist. In order to identify ecto-nucleotidases potentially associated with neural cells, we chose PC12 cells for analysis. PC12 cells revealed surface-located ATPase and ADPase activity with apparent K(m)-values of 283 microM and 243 microM, respectively. Using PCR we identified the mRNA of all members of the ecto-nucleoside triphosphate diphosphohydrolase family investigated (NTPDase1 to NTPDase3, NTPDase5/6), of ecto-nucleotide pyrophosphatase/phosphodiesterase3 (NPP3), tissue-non-specific alkaline phosphatase and ecto-5'-nucleotidase. The surface-located catalytic activity differed greatly between the various enzyme species. Our data suggest that hydrolysis of ATP and ADP is mainly due to members of the ecto-nucleoside triphosphate diphosphohydrolase family. Activity of ecto-5'-nucleotidase and alkaline phosphatase was very low and activity of NPP3 was absent. For a detailed analysis of the cellular distribution of ecto-nucleotidases single and double transfections of PC12 cells were performed, followed by fluorescence analysis. Ecto-nucleotidases were distributed over the entire cell surface and accumulated intracellularly in varicosities and neurite tips. PC12 cell ecto-nucleotidases are likely to play an important role in terminating autocrine functions of released nucleotides and in producing extracellular nucleosides supporting the survival and neuritic differentiation of PC12 cells.
...
PMID:Multiple ecto-nucleotidases in PC12 cells: identification and cellular distribution after heterologous expression. 1155 76

Snake envenomation employs three well integrated strategies: prey immobilization via hypotension, prey immobilization via paralysis, and prey digestion. Purines (adenosine, guanosine and inosine) evidently play a central role in the envenomation strategies of most advanced snakes. Purines constitute the perfect multifunctional toxins, participating simultaneously in all three envenomation strategies. Because they are endogenous regulatory compounds in all vertebrates, it is impossible for any prey organism to develop resistance to them. Purine generation from endogenous precursors in the prey explains the presence of many hitherto unexplained enzyme activities in snake venoms: 5'-nucleotidase, endonucleases (including ribonuclease), phosphodiesterase, ATPase, ADPase, phosphomonoesterase, and NADase. Phospholipases A(2), cytotoxins, myotoxins, and heparinase also participate in purine liberation, in addition to their better known functions. Adenosine contributes to prey immobilization by activation of neuronal adenosine A(1) receptors, suppressing acetylcholine release from motor neurons and excitatory neurotransmitters from central sites. It also exacerbates venom-induced hypotension by activating A(2) receptors in the vasculature. Adenosine and inosine both activate mast cell A(3) receptors, liberating vasoactive substances and increasing vascular permeability. Guanosine probably contributes to hypotension, by augmenting vascular endothelial cGMP levels via an unknown mechanism. Novel functions are suggested for toxins that act upon blood coagulation factors, including nitric oxide production, using the prey's carboxypeptidases. Leucine aminopeptidase may link venom hemorrhagic metalloproteases and endogenous chymotrypsin-like proteases with venom L-amino acid oxidase (LAO), accelerating the latter. The primary function of LAO is probably to promote prey hypotension by activating soluble guanylate cyclase in the presence of superoxide dismutase. LAO's apoptotic activity, too slow to be relevant to prey capture, is undoubtedly secondary and probably serves principally a digestive function. It is concluded that the principal function of L-type Ca(2+) channel antagonists and muscarinic toxins, in Dendroaspis venoms, and acetylcholinesterase in other elapid venoms, is to promote hypotension. Venom dipeptidyl peptidase IV-like enzymes probably also contribute to hypotension by destroying vasoconstrictive peptides such as Peptide YY, neuropeptide Y and substance P. Purines apparently bind to other toxins which then serve as molecular chaperones to deposit the bound purines at specific subsets of purine receptors. The assignment of pharmacological activities such as transient neurotransmitter suppression, histamine release and antinociception, to a variety of proteinaceous toxins, is probably erroneous. Such effects are probably due instead to purines bound to these toxins, and/or to free venom purines.
...
PMID:Ophidian envenomation strategies and the role of purines. 1173 31

An ATP diphosphohydrolase was identified in the plasma membranes isolated from promastigote forms of Leishmania amazonensis. Both ATP and ADP were hydrolysed at similar rates by the enzyme. Other nucleotides such as UTP, GTP and CTP were also degraded, revealing a broad substrate specificity. Adding ATP and ADP simultaneously, the amount of hydrolysis achieved was compatible with the presence of a single enzyme. ATPase activity was not affected by addition of vanadate, ouabain, thapsigargin, dicyclohexylcarbodiimide, oligomycin and bafilomycin A, thus excluding involvement of P-, F- and V-type ATPases. The effects of pH in the range 6.5-8.5 were examined using ATP or p-NPP as substrate. At pH 7.4, the phosphatase activity decreased, and did not show a significant contribution to ATP hydrolysis. In addition, the enzyme was not inhibited by levamisole and ammonium molybdate, excluding alkaline phosphatase and nucleotidase activities, respectively. Sodium azide (5-10 mM) caused inhibition of the ATP and ADP hydrolysis in a dose-dependent manner. Calcium was the best activating metal ion for both ATPase and ADPase activities. Ultrastructural cytochemical microscopy showed ATP diphosphohydrolase on the surface and flagellar pocket of the parasite. We have proposed that L. amazonensis ATP diphosphohydrolase may participate in the salvage pathway of nucleosides.
...
PMID:Characterization and cytochemical localization of an ATP diphosphohydrolase from Leishmania amazonensis promastigotes. 1186 92


<< Previous 1 2 3 4 Next >>

---