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

Studies were performed to examine the lateral organization of the NADPH oxidase system in the plasma membrane of human neutrophils. Analysis of the subcellular fractionation of human neutrophils by isopycnic sedimentation of cavitated cell lysates suggested that there may be more than one population of plasma membrane vesicles formed upon cell disruption. One population (30-32% sucrose) contained surface accessible wheat germ agglutinin binding sites, alkaline phosphatase activity, and cytochrome b. Another population (34-36% sucrose) contained membrane-bound flavin and, when the cells were prestimulated with phorbol myristate acetate (PMA), NADPH-dependent superoxide generating activity. Approximately 25% of the neutrophil cytochrome b cosedimented with the heavy population, confirming our previous hypothesis (Parkos et al. (1985) J. Biol. Chem. 260, 6541-6547) that only a fraction of the total cellular cytochrome b is involved in superoxide production. The heavy plasma membrane fraction was also enriched in membrane associated actin and fodrin as detected by Western blot analysis. After extraction of the plasma membrane vesicles with detergent cocktails, the majority of superoxide generating activity remained associated with the detergent insoluble pellet. Western blot analysis demonstrated that the pellets were also enriched in actin. Further analysis of these pellets using rate-zonal detergent-containing sucrose density gradients indicated that the superoxide generating complex had an approximate sedimentation coefficient of 80 S, suggesting that the neutrophil superoxide generating system may form a complex on the plasma membrane which is associated with or somehow organized by the membrane skeletal matrix. This organization may be of functional relevance not only to the actual production of superoxide, but also to the targeting of microbicidal oxidants.
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PMID:The lateral organization of components of the membrane skeleton and superoxide generation in the plasma membrane of stimulated human neutrophils. 255 84

The effect of sodium butyrate was examined on the growth and phenotypic expression of a cell line derived from the ascitic fluid of an untreated patient with ovarian carcinoma. The chemical inducer of differentiation, sodium butyrate, markedly enhances the activity of the membrane-bound glycoprotein enzymes, alkaline phosphatase and gamma-glutamyl transpeptidase. The alkaline phosphatase corresponds to placental Regan type. Sodium butyrate (1 mM) alone has only a small inhibitory effect on cell growth. However, it was shown to potentiate the anti-proliferative effect of Adriamycin and to render the cells sensitive to cis-platinum.
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PMID:Sodium butyrate enhances the activities of membranal enzymes and increases drug sensitivity in a cell line from ascitic fluid of an ovarian carcinoma patient. 257 49

Two forms of alkaline phosphatase, extracted from human liver and named API1 and API3, are of high molecular mass, but API3 is the larger molecule and is membrane-bound while API1 is smaller and soluble. Enzyme kinetics are identical. It is suggested that API1 is produced from API3 by an endoprotease. We demonstrated the action of an endoprotease in human liver homogenate converting API3 into API1. In the absence of this enzyme no conversion occurred. This enzyme is active at an acidic pH (less than 6.5) in the presence of Ca.. or Mg.. -ions. It is inhibited by traces of EDTA. It is insensitive to diisopropyl fluoro-phosphate, to leupeptin and to reducing or oxidizing chemicals. At alkaline pH (8.6) its activity is rapidly destroyed. The enzyme is stable in acidic buffer. We conclude that API1 is indeed formed from API3 in the living cell by enzymatic conversion.
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PMID:Endoprotease in human liver transforming multiple forms of alkaline phosphatase. 265 95

The effects of Gossypol acetic acid (10 mg/kg b. wt. daily for 15 days), an experimental male antifertility agent and its subsequent withdrawal for another 15 days, on the structure and functions of the rat small intestinal tract have been investigated. Gossypol feeding causes a reduction in body weight and intestinal weight, length, protein, and nucleic acid contents. A 27%-50% reduction in the uptake of glucose, alanine, leucine, and calcium is observed after Gossypol feeding which is found to be reversible after 15 days of withdrawal of the drug. Gossypol also causes a significant reduction in the activities of sucrase, lactase, maltase and alkaline phosphatase in the intestinal homogenates as well as in the purified brush border membrane of the microvillus. A decrease in the maximum of apparent enzyme velocity and no change in the substrate affinity constant in these digestive hydrolases are observed on Gossypol treatment. It also causes a shift in the transition temperature in these enzymes and predictably changes the energy of activation both below and above the temperature of transition, although the Arrhenius expression of the temperature dependence still shows proximity, non-linearity, and is parallel to the control group. These changes are reversed on withdrawal of the drug and during the subsequent recovery period. Recovery experiments also show near identical values in kinetic parameters (Kt and Jmax) of 14C-glucose uptake in jejunal segments both in the presence and absence of Na+ ions. Also, no difference is observed between the control and recovery groups with respect to body and intestinal weight, intestinal length, and DNA, RNA, protein, lactate dehydrogenase and glucose-6-phosphate phosphohydrolase values in the intestinal homogenates. Phospholipid, cholesterol and sialic acid levels in both the groups also show nearly identical values. Molecular mechanism of the effects of Gossypol on brush border membrane-bound enzyme/carrier molecules operation is discussed in view of the kinetic and thermodynamic data obtained.
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PMID:Reversibility of the effects of gossypol acetic acid, an antispermatogenic/antifertility agent on the intestinal structure and functions of male albino rats. 274 9

The larval midgut epithelial cell of the silkworm, Bombyx mori, has two forms of alkaline phosphatase and trehalase, soluble and membrane-bound. Alkaline phosphatase and trehalase of the latter form are found in the brush border membrane and the basolateral membrane, respectively. In this work we studied the membrane anchors of these membrane-bound enzymes. Alkaline phosphatase was solubilized by phosphatidyl-inositol-specific phospholipase C, but not by papain. Conversely, trehalase was released from the membrane by papain, but not by phosphatidylinositol-specific phospholipase C. Both enzymes were solubilized in an amphiphilic form with 0.5% Triton X-100 plus 0.5% sodium deoxycholate (pH 7.0). The detergent-solubilized alkaline phosphatase and trehalase were converted to hydrophilic form on incubation with phosphatidylinositol-specific phospholipase C and papain, respectively. The effects of papain on solubilization and conversion of trehalase were completely inhibited by leupeptin. These results suggest that, in the silkworm larvae, alkaline phosphatase is anchored in the brush-border membrane via a glycosyl-phosphatidylinositol, while trehalase is associated with the basolateral membrane through a hydrophobic segment of the polypeptide.
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PMID:Membrane anchors of alkaline phosphatase and trehalase associated with the plasma membrane of larval midgut epithelial cells of the silkworm, Bombyx mori. 276 26

Several compounds were tested as inhibitors of the alkaline phosphatase (AlkPase) activity associated with the isolated brush border membrane of the tapeworm, Hymenolepis diminuta. Molybdate, arsenate, arsenite and beta-glycerophosphate (BGP) were competitive inhibitors of the hydrolysis of p-nitrophenyl phosphate, while levamisole and clorsulon were uncompetitive and mixed inhibitors, respectively. Molybdate was also a competitive inhibitor of the hydrolysis of BGP and 5'-adenosine monophosphate, and levamisole was an uncompetitive inhibitor of BGP hydrolysis. The apparent inhibitor constants (Ki') for molybdate and levamisole were virtually identical regardless of the substrate, and these data support the hypothesis that the AlkPase activity is represented by a single membrane-bound enzyme with low substrate specificity. Quinacrine, Hg2+, and ethylenediaminetetraacetate were also potent inhibitors of the AlkPase activity, but the mechanisms by which these latter three inhibitors function were not clear.
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PMID:Competitive, uncompetitive, and mixed inhibitors of the alkaline phosphatase activity associated with the isolated brush border membrane of the tapeworm Hymenolepis diminuta. 276 48

Isolation of two membrane-bound alkaline phosphatase (AP) species from avian growth plate cartilage matrix vesicle (MV) fractions is described. AP was first released from the membranes by phosphatidylinositol-specific phospholipase C (PIase C), followed by chromatography on DEAE-Bio-Gel A and Reactive-Red agarose. Two AP species having apparent Mr of 81.5 and 77 kDa by SDS-PAGE were purified in high yield and specific activity by this simple method. Treatment with neuraminidase to remove sialic acid residues reduced their size slightly, but did not diminish the difference in Mr between the two species. Digestion with N-glycanase, however, decreased both AP species to a common size of 59 kDa. This reveals that both enzymes are highly glycosylated and suggests that the two forms may result from differences in degree of glycation. The amino acid compositions of the two avian enzyme forms are very similar, but are markedly enriched in serine, glycine and glutamate when compared to those reported for mammalian liver-kidney-bone AP. Possible differences in amino acid sequence between the two avian forms have not been excluded. The cross-reactivity of polyclonal antibodies to these enzymes with bovine kidney, but not intestinal AP, indicate that the avian cartilage APs are of the liver-kidney-bone isozyme type.
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PMID:Isolation of two glycosylated forms of membrane-bound alkaline phosphatase from avian growth plate cartilage matrix vesicle-enriched microsomes. 280 49

We present a monoclonal IgG1 antibody, KiMy1R, which is specific for macrophages and their derivatives in the lymphatic tissue of the rat, and evaluate the distribution of subsets of mononuclear cells in popliteal and para-aortal lymph nodes of Wistar rats after injection of 50 mg DPH into the hindpads. Compared with resting lymphatic tissue and lymph nodes of animals treated with phenobarbital, DPH induced a significant increase (P less than 0.01) of the proportion of phagocytic cells. Furthermore, the soluble antigen alkaline phosphatase was traced after inoculation into the footpads of rats: in locoregional lymph nodes the percentage (mean 12.8/10(3] and the total number (mean 476 x 10(3) cells/lymph node) of cells with membrane-bound or intracytoplasmic alkaline phosphatase, as detected by a monoclonal anti-alkaline phosphatase antibody, were significantly higher (P less than 0.001) in animals pretreated with DPH than in rats pretreated with phenobarbital (mean 2.1/10(3); 31.2 x 10(3) cells/lymph node) and in untreated animals (mean 1.9/10(3); 4.1 x 10(3) cells/lymph node). If verified in humans, the effect of DPH in enhancing the number and function of macrophages and other antigen-presenting cells may exert favourable effects in patients with impairment of the mononuclear phagocytic system.
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PMID:Enhancement in number and function of antigen-presenting cells in the lymphatic tissue of rats after in vivo administration of diphenylhydantoin (DPH). 280 17

In isolated erythrocyte membranes, increasing the free Mg2+ concentration from 0.5 to 10 mM progressively activates the membrane-bound phosphatidylinositol (PtdIns) kinase and leads to the establishment of a new equilibrium with higher phosphatidylinositol 4-phosphate (PtdIns4P) and lower PtdIns concentrations. The steady-state turnover of the phosphomonoester group of PtdIns4P also increases at high Mg2+ concentrations, indicating a simultaneous activation of PtdIns4P phosphomonoesterase by Mg2+. Half-maximum inhibition of PtdIns kinase occurs at 10 microM free Ca2+ in the presence of physiological free Mg2+ concentrations. Increasing free Mg2+ concentrations overcome Ca2+ inhibition of PtdIns kinase. In the presence of Ca2+, calmodulin activates Ca2+-transporting ATPase 5-fold, but does not alter pool size and radiolabelling of PtdIns4P. In intact erythrocytes, adding EGTA or EGTA plus Mg2+ and the ionophore A23187 to the external medium does not exert significant effects on concentration and radiolabelling of polyphosphoinositides when compared with controls in the presence of 1.4 mM free Ca2+.
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PMID:Influence of Ca2+ and Mg2+ on the turnover of the phosphomonoester group of phosphatidylinositol 4-phosphate in human erythrocyte membranes. 282 96

Two soluble forms of inositol phosphate 5-phosphomonoesterase have been partially purified and characterized from rat brain and are referred to as type 1 and type 2 according to their order of elution from DEAE-Sepharose. Together, these enzymes represent 26 +/- 3% (mean +/- S.E., n = 4) of the total inositol 1,4,5-triphosphate (Ins(1,4,5)P3) phosphatase activity assayed in crude brain homogenate and are present in approximately equal total activities in a 100,000 x g supernatant, with the remainder being membrane-bound. Both soluble enzymes require Mg2+ for activity, are moderately inhibited by Ca2+ in the micromolar range, and can be inhibited by millimolar concentrations of a variety of phosphorylated compounds. The type 1 enzyme has been purified to a specific activity of 1.06 mumol/min/mg protein. It elutes as a 60-kDa protein on Sephacryl S-200. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the type 1 enzyme correlates with a pair of protein bands of 66 and 60 kDa. It has apparent Km values of 3 and 0.8 microM for Ins(1,4,5)P3 and inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4), respectively, and hydrolyses Ins(1,4,5)P3 approximately 12 times faster than Ins(1,3,4,5)P4. The type 2 enzyme has been purified to a specific activity of 15.2 mumol/min/mg protein, elutes as a protein of 160 kDa on Sephacryl S-300, and migrates as a similarly sized subunit on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It has an apparent Km for Ins(1,4,5)P3 of 18 microM. Its apparent Km for Ins(1,3,4,5)P4, however, is greater than 150 microM, suggesting that this enzyme is primarily an Ins(1,4,5)P3 5-phosphomonoesterase. The relationship of these two enzymes to the inositol tris/tetrakisphosphate pathway is discussed.
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PMID:Purification and characterization of two types of soluble inositol phosphate 5-phosphomonoesterases from rat brain. 282 17


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