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)

Methods have been developed for the addition of different metal ion species to the three distinct pairs of metal sites (A, B, and C) found in the dimer of apoalkaline phosphatase. This allows the preparation of hybrid alkaline phosphatases in which A and B sites of each monomer contain two different species of metal ion or the A and B sites of one monomer contain the same species of metal ion, while the adjacent monomer contains a second species. The following hybrids have been characterized in detail: (Zn(II)ACd(II)B)2 alkaline phosphatase, (Zn(II)AMg(II)B)2 alkaline phosphatase, (Cd(II)AZn(II)B)2 alkaline phosphatase, and (Zn(II)AZn(II]B)(Cd(II)ACd(II)B) alkaline phosphatase. 31P and, where appropriate, 113Cd NMR have been used to monitor the behavior of the covalent (E-P) and noncovalent (E X P) phosphointermediates and of the A and B metal ions. From the pH dependencies of the E-P in equilibrium E X P in equilibrium E + Pi equilibria, it is clear that A site metal is the dominant influence in dephosphorylation of E-P and may have a coordinated water molecule, which ionizes to ZnOH- at a low pH providing the nucleophile for dephosphorylation. A site metal also serves to coordinate phosphate in the E X P complex. B site metal has a much smaller effect on dephosphorylation rates, although it does dramatically alter the Pi dissociation rate, which is the rate-limiting step for the native enzyme at alkaline pH, and is probably important in neutralizing the charge on the phosphoseryl residue, thus potentiating the nucleophilic attack of the OH- bound at A site. Phosphate dissociation is slowed markedly by replacement of B site zinc by cadmium. There is clear evidence for long range effects of subunit-subunit interactions, since metal ion and phosphate binding at one active center alters the environments of A and B site metal ions and phosphoserine at the other active site.
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PMID:Zn(II)-113Cd(II) and Zn(II)-Mg(II) hybrids of alkaline phosphatase. 31P and 113Cd NMR. 637 Sep 97

Lysobacter enzymogenes produces an extracellular phosphatase (EC. 3.1.3.1) during the stationary phase of growth. The cells also produce a cell-associated alkaline phosphatase. This enzyme is found in the particulate fraction of cell extracts and may be membrane bound. The production of both phosphatases, especially the extracellular enzyme, is reduced by inorganic phosphate. The extracellular phosphatase was purified to a specific activity of 270 U/mg primarily by chromatography on carboxymethyl cellulose and gel filtration. The enzyme is stable under normal storage conditions but is rapidly inactivated above 70 degrees. It consists of one polypeptide with an approximate molecular weight of 25,000. The pH optimum is 7.5, and the Km for p-nitrophenylphosphate is 2.2 X 10(-4) M. The enzyme degrades a number of other phosphomonoesters but at a reduced rate compared with the rate obtained with p-nitrophenylphosphate. Phosphate and arsenate inhibit the enzyme, but EDTA and other chelating agents have no effect. The lack of a metal ion requirement for activity, the lower molecular weight, the soluble nature of the enzyme, and the lower pH optimum clearly distinguish the extracellular phosphatase from the cell-associated phosphatase and from other bacterial phosphatases.
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PMID:Production of two phosphatases by Lysobacter enzymogenes and purification and characterization of the extracellular enzyme. 642 86

beta-Glucuronidase from human lung neoplasms of various histological types and from uninvolved tissues was studied. A significant elevation of beta-glucuronidase activity was observed in adenocarcinoma and squamous cell carcinoma of the lung as compared with the corresponding uninvolved tissues (P less than 0.01). Saccharo-1,4-lactone, a strong inhibitor of the enzyme, exhibited a substantially greater stabilizing effect on the adenocarcinoma enzyme than on the other enzymes. However, removal of the carbohydrate moiety from the adenocarcinoma enzyme by treatment with endo-beta-N-acetylglucosamidase H (endoglycosidase H) brought about a decrease in the stabilizing effect. Tumor beta-glucuronidase showed considerable negative charge heterogeneity in the pI range from 4.2 to 6.2 in isoelectric focusing on polyacrylamide gel. Upon treatment with exogenous alkaline phosphatase or endoglycosidase H, the heterogenous variant forms of the tumor enzyme appeared to partly or completely lose their negative charge and to be converted into forms similar to those of the normal lung enzyme. These data strongly suggest that the variants are highly phosphorylated on the oligosaccharide chains of the enzyme. An experiment on the labelling of beta-glucuronidase with [32P]-phosphoric acid provided further evidence that the acidic variants found in lung cancers are extensively phosphorylated forms of the enzyme.
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PMID:Cancer-associated alteration of beta-glucuronidase in human lung cancer: elevated activity and increased phosphorylation. 643 19

The effect of phenylglyoxylation on brush-border-membrane functions was studied with membrane vesicles from rat kidney cortex. Na+-gradient-dependent uptake of phosphate, glucose and alanine was inhibited by 65, 88 and 70% by pre-incubation of vesicles with 50 mM-phenylglyoxal for 2 min. The inhibition showed a dependency for alkaline pH. Borate co-operativity in butanedione inactivation was used to prove that inhibition was caused by arginine modification. Intravesicular volumes, alkaline phosphatase, aminopeptidase M and Na+-H+ exchange were not affected by phenylglyoxal treatment. Inhibition of phosphate uptake was studied in more detail and showed that the chemical modification introduced by phenylglyoxal inhibited the overshoot of phosphate uptake caused by the Na+ gradient, and decreased the apparent maximal velocity of the phosphate-transport system in its interaction with Na+. Phosphate uptake measured in the absence of Na+ was not affected by phenylglyoxal. Shunting of the transmembrane electrical potential with K+ and valinomycin had no effect on phenylglyoxal inhibition, proving that the alteration of transmembrane electrical potential could not be responsible for this effect. Phenylglyoxal had no ionophoric effect on the Na+ gradients studied (1-100 mM). Na+ efflux was also unaffected by phenylglyoxal treatment. Na+, harmaline and amiloride were ineffective in protecting against phenylglyoxal inhibition, suggesting that the site modified was not an Na+-binding site. These results indicate the involvement of highly reactive arginine residues in phosphate, glucose and alanine uptake.
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PMID:Effect of arginine modification on kidney brush-border-membrane transport activity. 650 41

Prostaglandins seem to be involved in the pathogenesis of juxtaarticular osteopenia in rheumatoid arthritis. Therefore the influence of prostaglandins on in vitro electrolyte metabolism of human trabecular bone was tested. Trabecular bone was prepared from femoral heads of patients who had undergone hip replacement surgery for coxarthrosis. 500 mg samples of trabecular bone were incubated in modified Eagle's minimal essential medium. Net electrolyte movements between bone and incubation medium were measured. PGE2 caused an increase in the release of calcium (Ca) and magnesium (Mg) from bone into incubation medium as compared to controls (PGE2 1 micrograms/ml: Ca = 0.87 +/- 0.09 mmol/l*, Mg = 0.44 +/- 0.03 mmol/l*; controls: Ca = 0.81 +/- 0.09 mmol/l, Mg = 0.41 +/- 0.05 mmol/l; n = 15, *p less than 0.001). The effect of PGE2 was dose-dependent and comparable to the effect of human parathyroid hormone 1-34 (hPTH 1-34). PGE2 turned out to be the most potent prostaglandin on human trabecular bone. PGE1 and PGF2 alpha had about 50% and PGF1 alpha about 40% of the potency of PGE2. PGA1 and PGA2 had no effect. The effect of PGE2 could be completely inhibited by human calcitonin (hCT), similar to the inhibition of the effect of hPTH 1-34 by hCT. The effect of PGE2 was not further enhanced by hPTH 1-34. Magnesium metabolism was affected in all experiments in the same way as calcium metabolism. Phosphate metabolism, release of alkaline phosphatase and hydroxyproline from bone into incubation medium were not affected by prostaglandins.
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PMID:[Effect of prostaglandins on in vitro electrolyte metabolism in human spongiosa]. 659 15

Phosphate binding by rat renal brush border membranes occurs on a single protein, as visualized by SDS polyacrylamide gel electrophoresis. The same protein can also be specifically labelled by gamma-32P ATP at 0 degree C or in the absence of magnesium. The phosphate binding protein co-migrates with monomers of two alkaline phosphatase activity bands previously localized on acrylamide gel. Measurement of binding by TCA precipitation, ion-exchange chromatography and dialysis gave an average of 31.1 +/- 5.7 pmol phosphate bound/mg protein. Alkaline phosphatase would then represent 0.23% of total brush border membrane protein. Maximal binding activity is obtained at pH 6.5, but when membranes are phosphorylated at pH 6.5 and the pH increased to 9.4, 50% of the bound radioactivity is released. The binding of phosphate to this protein presents two different apparent Km: one at 40 microM for low and one at 390 microM for high substrate concentrations. The membrane bound phosphate is readily exchangeable with phosphate in the medium. Phosphate binding and phosphate release are complete within 5 s. Alkaline phosphatase substrates and EDTA are potent inhibitors of phosphate binding and produce over 90% inhibition. Characteristics of phosphate binding for kidney membrane bound alkaline phosphatase seem very similar to the soluble form of the enzyme from various sources.
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PMID:Characterization of phosphate binding by alkaline phosphatase in rat kidney brush border membrane. 663 81

Two siblings (boy and girl) born to a mother with familial hypophosphatemic rickets had abnormal values of serum phosphorus and serum alkaline phosphatase at the age of six weeks. At this age therapy with 1 alpha-hydroxycholecalciferol (1 alpha OHD3) and phosphate was started resulting in both siblings having normal growth of body length and radiological healing of the bone lesions but persistently low values of fasting serum phosphorus during the time of observation up to 60 and 26 months of age, respectively. Phosphate and 1 alpha OHD3 have a positive influence on serum phosphorus through their effect on the intestine. Neither of the patients developed hypercalcaemia during treatment. It seems, therefore, that the early administration of 1 alpha OHD3 with phosphate in infants with familial hypophosphatemic rickets prevents dwarfism and has a positive effect on intestinal absorption of phosphorus but not on fasting hypophosphatemia.
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PMID:The management of siblings with familial hypophosphatemic rickets. 665 89

Brush-border membrane vesicles prepared from rabbit kidney cortex were incubated at 37 degrees C for 30 min with phosphatidylinositol-specific phospholipase C. This maneuver resulted in a release of approx. 85% of the brush-border membrane-linked enzyme alkaline phosphatase as determined by its enzymatic activity. Transport of inorganic [32P]phosphate (100 microM) by the PI-specific phospholipase C-treated brush-border membrane vesicles was measured at 20-22 degrees C in the presence of an inwardly directed 100 mM Na+ gradient. Neither initial uptake rates, as estimated from 10-s uptake values (103.5 +/- 6.8%, n = 7 experiments), nor equilibrium uptake values, measured after 2 h (102 +/- 3.4%) were different from controls (100%). Control and PI-specific phospholipase C-treated brush-border membrane vesicles were extracted with chloroform/methanol to obtain a proteolipid fraction which has been shown to bind Pi with high affinity and specificity (Kessler, R.J., Vaughn, D.A. and Fanestil, D.D. (1982) J. Biol. Chem. 257, 14311-14317). Phosphate binding (at 10 microM Pi) by the extracted proteolipid was measured. No significant difference in binding was observed between the two types of preparations: 31.0 +/- 9.37 in controls and 29.8 +/- 8.3 nmol/mg protein in the proteolipid extracted from PI-specific phospholipase C-treated brush-border membrane vesicles. It appears therefore that alkaline phosphatase activity is essential neither for Pi transport by brush-border membrane vesicles nor for Pi binding by proteolipid extracted from brush-border membrane. These results dissociate alkaline phosphatase activity, but not brush-border membrane vesicle transport of phosphate, from phosphate binding by proteolipid.
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PMID:Enzymatic removal of alkaline phosphatase from renal brush-border membranes. Effect on phosphate transport and on phosphate binding. 669 85

The alkaline phosphatase of Plectonema boryanum shows a considerable increase in activity following placement of the cells in a phosphate free medium. Five days of phosphate starvation result in a 14-fold increase of alkaline phosphatase activity. Growth in the presence of inhibitors of transcription and translation indicate that the synthesis of the enzyme is de novo. Orthophosphate causes an immediate inhibition of enzyme activity. Enzyme was extracted from P. boryanum with lysozyme or polymyxin B treatment in order to make comparative studies of cell bound and cell free enzyme. Of several enzyme specific inhibitors tested, mercuric chloride was the most effective. Temperature studies showed that the cell bound enzyme was most active at 40 degrees C while the cell free enzyme was most active at 70 degrees C. The pH optimum was 9 for the cell free enzyme, and 8.8 for the cell bound. The enzyme was tested to determine if it could hydrolyse a number of different organic compounds. It hydrolysed p-nitrophenol phosphate 100%, fructose-6-phosphate 45%, beta-glycerol phosphate 25% and other compounds to a lesser degree. Of seventeen other Cyanobacteria tested for alkaline phosphatase, all were positive, and of these eleven were inducible for the enzyme. Ten of the isolates released some of the enzyme into the culture medium. Michaelis constants for the enzyme were also determined.
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PMID:Physiological aspects of alkaline phosphatase in selected cyanobacteria. 679 13

Simultaneous reduction in alkaloid yield and level of phosphatases by high concentrations of phosphate was observed in Claviceps sp. SD-58. Tryptophan-induced culture showed an increase in alkaloid yield and the level of phosphatases. Phosphate caused repression of both acid phosphatase (isoenzyme I) and alkaline phosphatase (isoenzymes III and V).
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PMID:Alkaloid production by Claviceps sp. SD-58; involvement of phosphatase isozymes. 683 54


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