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)

The disruption of the molecular organization of the plasma membrane of leukocytes by phagocytosable particles, or by agents such as surfactants, antibodies, phospholipase C, fatty acids and chemotactic factors, leads to a stimulation of the phagocyte oxidative metabolism. Concanavalin A (Con A) has been used as a tool to study the mechanism of this metabolic regulation. The binding of Con A to the surface of polymorphonuclear leukocytes (PMNL) or macrophages produces a rapid enhancement of oxygen uptake and glucose oxidation through the hexose monophosphate pathway (HMP). This is explained by an activation of the granular NADPH oxidase, the key enzyme in the metabolic stimulation. The effect of Con A is not due to endocytosed lectin, since Con A covalently coupled to large sepharose beads still acts as stimulant. The metabolic changes caused by Con A are reversible. If, after the onset of stimulation, sugars with high affinity for Con A are added to the leukocyte suspension, the activity of granular NADPH oxidase and the rate of respiration and glucose oxidation return to their resting values. The metabolic burst, while partially supressed by treatment of PMNL with iodoacetate, sodium flouride and cytochalasin B, is slightly increased by colchicine. Con A induces a selective release of granular enzymes (beta-glucuronidase, peroxidase, alkaline phosphatase) from PMNL, whereas no leakage of cytoplasmic enzymes is observed. The enzyme release is inhibited by iodoacetate and by drugs known to increase cell levels of cyclic AMP. Based on a current view of the mode of interaction between Con A and cell surfaces, a model of the metabolic disruption of leukocytes is presented.
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PMID:Concanavalin A as a probe for studying the mechanism of metabolic stimulation of leukocytes. 16 45

4-Nitrophenyl and 2-napthyl monoesters of phenylphosphonic acid have been synthesized, and an enzyme catalyzing their hydrolysis was resolved from alkaline phosphatase of a commerical calf intestinal alkaline phosphatase preparation by extensive ion-exchange chromatography, chromatography on L-phenylalanyl-Sepharose with a decreasing gradient of (NH4) 2SO4, and gel filtration. Detergent-solubilized enzyme from fresh bovine intestine was purified after (NH4)2SO4 fractionation by the same technique. The purified enzyme is homogeneous by polyacrylamide gel electrophoresis and sedimentation equilibrium centrifugation. It has a molecular weight of 108,000, contains approximately 21% carbohydrate, and has an amino acid composition considerably different from that reported from alkaline phosphatase from the same tissue. The homogeneous intestinal enzyme, an efficient catalyst of phosphonate ester hydoolysis but not of phosphate monoester hydrolysis, was identified as a 5'-nucleotide phosphodiesterase by its ability to hydrolyze 4-nitrophenyl esters of 5'-TMP but not of 3'-TMP. Also consistent with this identification was the ability of the enzyme to hydrolyze 5'-ATP to 5'-AMP and PPi, NAD+ to 5'-AMP and NMN, TpT to 5'-TMP and thymidine, pApApApA to 5'-AMP, and only the single-stranded portion of tRNA from the 3'-OH end. Snake venom 5'-nucleotide phosphodiesterase also hydrolyzes phosphonate esters, but 3'-nucleotide phosphodiesterase of spleen and cyclic 3',5'-AMP phosphodiesterase do not. Thus, types of phosphodiesterases can be conveniently distinguished by their ability to hydrolyze phosphonate esters. As substrates for 5'-nucleotide phosphodiesterases, phosphonate esters are preferable to the more conventional esters of nucleotides and bis(4-nitrophenyl) phosphate because of their superior stability and ease of synthesis. Furthermore, the rate of hydrolysis of phosphonate esters under saturating conditions is greater than that of the conventional substrates. At substrate concentrations of 1 mM the rates of hydrolysis of phosphonate esters and of nucleotide esters are comparable and both superior to that of bis(4-nitrophenyl) phosphate.
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PMID:Hydrolysis of phosphonate esters catalyzed by 5'-nucleotide phosphodiesterase. 17 Sep 64

Rat spermatozoa from the cauda epididymidis, freed from their cytoplasmic droplets and acrosomes, were found to have a lower lipid content and to incorporate [14C]glucose into their glycerides and glycerophosphatides at a lower rate than spermatozoa from the caput epididymidis. Against the background of the activities of some glycolytic enzymes which remained constant the activity of alkaline phosphatase decreased in spermatozoa migrating through the epididymis, whereas the activity of monoglyceride lipase increased. The corresponding enzyme activities of non-flagellate germ cells of the testis were measured for comparison. The triglyceride lipase of non-flagellate germ cells and of spermatozoa from both caput and cauda epididymidis was activated by cyclic 3':5'-AMP.
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PMID:Changes in lipase and phosphatase activities of rat spermatozoa in transit from the caput to the cauda epididymidis. 17 29

In ten patients with Paget's disease of bone (Group I) intramuscular injection of 50 MRC units of synthetic Salmon calcitonin (SCT) induced a marked decrease of serum calcium (-1,444 mg%), serum phosphorus (-1,06 mg%), urinary total hydroxyproline (-71%), and a marked increase of urinary cyclic AMP (+ 114%). These changes occur at maximum 6 hours after the injection with a return to the initial values after 24 hours. In six other patients with Paget's disease (Group II) the acute biological effects were of the same nature and magnitude after the injection of 100 MRC units of SCT. In this group a significant but temporary increase of the plasma parathyroid hormone level was demonstrated. The magnitude of the hypocalcemia seems proportional to the initial serum alkaline phosphatase and urinary hydroxyproline levels. After one month of treatment, the alkaline phosphatase and urinary hydroxyproline have more marked and more regular decrease in group II who received 100 MRC units of SCT daily than in group I who received 50 MRC units three times a week. The cellular mechanisms of these biological changes are discussed. A posology of two daily injections of 50 MRC units of SCT is suggested when a quick and maximum stoppage of pagetic remodeling is required.
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PMID:[Short-term biological effects of synthetic salmon calcitonin in Paget's disease. Influence of posology]. 17 38

The P4 variant of Dictyostelium discoideum is characterized by the production of fruiting structures in which the overall proportion of stalk to spore material is increased, relative to the wild type. The altered morphology of the mutant is due to increased sensitivity to cyclic AMP which promotes stalk cell differentiation. In the presence of 10-4 M-cyclic AMP the entire population of P4 amoebae forms clumps of stalk cells on the surface of the dialysis membrane support. Measurement of changes in activity of a range of developmentally-regulated enzymes during the development of P4 in the presence and absence of cyclic AMP has allowed us to identify three classes of enzyme: (i) Those, such as beta-glucosidase II, trehalose-6-phosphate synthetase and uridine diphosphogalactose-4-epimerase, which are required for the production of spores. (ii) Enzymes, primarily but perhaps not exclusively, required during stalk cell formation. Typical of these are N-acetylglucosaminidase and alkaline phosphatase. (iii) General enzymes, such as threonine dehydrase, alpha-mannosidase and uridine diphosphoglucose pyrophyosphorylase, which are present inboth pre-stalk and pre-spore cells and appear to be necessary for the development of both cell types.
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PMID:Enzyme activity changes during cyclic AMP-induced stalk cell differentiation in P4, a variant of Dictyostelium discoideum. 17 91

Cholera enterotoxin, 45 mug per 250 g body weight, administered intravenously to rats, caused a 6-fold rise in the activity of liver alkaline phosphatase in 12 hr. There was no change in bile volume or in the concentration or total bile content of Na+, K+, HCO3-, or Cl- for 36 hr after the administration of cholera toxin. However, bile phospholipid output fell markedly from a control level of 15.0 +/- 1.0 mumol per 6 hr to a low level of 4.0 +/- 1.2 mumol per 6 hr in the 12- to 18-hr collection, P less than 0.001. There was a similar fall in bile acid secretion, from a control value of 9.8 +/- 0.4 mumol per 6 hr to 4.1 +/- 0.9 mumol in the 12- to 18-hr period, P less than 0.01. The cholera effect was prolonged. Bile acid and phospholipid secretion rates did not return to control values until 30 to 36 hr after the administration of cholera enterotoxin. The cholera toxin-induced reductions in bile acid and phospholipid secretion into bile did not appear to be mediated by adenyl cyclase or cyclic AMP because neither glucagon, a known stimulator of liver adenyl cyclase, nor dibutyryl cyclic AMP had any effect on the secretion into bile of bile acids or phospholipid. The administration of cholera toxin was not associated with any increase in the secretion of free choline into bile. Glucagon and dibutyryl cyclic AMP, two other substances known to increase the activity of rat liver alkaline phosphatase, also had no stimulatory effect on the secretion of free choline into bile. The results do not support the hypothesis that the main function of rat liver alkaline phosphatase is to facilitate the excretion of free choline into bile.
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PMID:Effects of cholera enterotoxin, glucagon, and dibutyryl cyclic AMP on rat liver alkaline phosphatase, bile flow, and bile composition. 17 82

The purpose of this study was to try to differentiate histochemically between the various enzymes which may catalyze the hydrolysis of ATP in developing rat dental tissues. Freeze cut and freeze dried sections of molar and incisor teeth were incubated in lead capture-based media at pH 5.0, 7.2 or 9.4 with one of the following substrates: beta-glycerophosphate, AMP, ADP, ATP, AMP-PNP and tetrasodium pyrophosphate. To establish the enzymatic nature of the hydrolysis parallel sections were incubated after prior fixation in either formaldehyde or glutaraldehyde. By comparing the enzymatic stainings obtained with the various substrates and at the different pH:s, it was concluded that ATP can be visibly hydrolyzed in rat dental tissues by alkaline phosphatase (stratum intermedium, apical part of maturation ameloblasts, basal part of all ameloblasts, odontoblasts and subodontoblastic layer), specific ATPase (apical and basal parts of secretory ameloblasts) and ATP pyrophosphatase and/or adenylate cyclase (stratum intermedium, odontoblasts). Acid phosphatase, specific ADPase, 5'-nucleotidase, inorganic pyrophosphatase, 3':5'-cyclic-AMP-phosphodiesterase and adenylate kinase on the other hand, seem not to be engaged in the ATP hydrolysis to such a degree as to complicate the interpretation of the histochemical staining. The alkaline phosphatase part of the ATP hydrolysis appeared to be rather insensitive to aldehyde fixation, while the hydrolysis effected by specific ATPase and ATP pyrophosphatase and/or adenylate cyclase was extinguished after fixation with formaldehyde for 4 h or glutaraldehyde for 10 min.
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PMID:Adenosine triphosphate hydrolysis in rat dental tissues. A histochemical study to differentiate the enzymes involved. 18 60

The possible role of cytoplasmic microtubules in the renal handling of phosphate and its regulation by parathyroid hormone (PTH) was evaluated with colchicine, a microtubule-disrupting agent. Colchicine-treated rats were thyroparathyroidectomized (TPTX) and subsequently infused with PTH. Treatment with a total dose of 1 mg colchicine had no effect on glomerular filtration rate or fractional excretions of sodium and potassium. Fractional excretion of phosphate in colchicine-treated TPTX rats was significantly higher compared with TPTX controls. After PTH infusion, control rats responded with increases in fractional excretion of phosphate and urinary cyclic AMP but colchicine-treated rats had variable and insignificant changes in both parameters. Fractional excretion of sodium and potassium did not change significantly after PTH. Renal cortical activities of cyclic AMP phosphodiesterase, soluble alkaline phosphatase, cytochrome oxidase, leucine aminopeptidase, or basal adenylate cyclase were not significantly affected by colchicine treatment. On the other hand, stimulation of adenylate cyclase by a submaximal dose of PTH was markedly decreased in colchicine-treated rats, and the activity of membrane-bound alkaline phosphatase was also significantly decreased. The binding of radioactive colchicine in renal cortical extracts from rats treated with colchicine was significantly diminished. These results suggest that disruption of cytoplasmic microtubules in renal cortical cells interferes with phosphate transport and its regulation by PTH.
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PMID:Effect of colchicine on urinary phosphate and regulation by parathyroid hormone. 18 12

Cardiac myofibrils were purified from canine myocardium, and the regulatory proteins (troponin + tropomyosin) were extracted and shown to contain endogenous cyclic AMP-dependent protein kinase activity. Other cyclic nucleotide stimulated the protein kinase activity but only at higher concentrations. The enzyme was able to catalyze phosphorylation of conventional substrates such as histones and casein as well as a component of the regulatory protein fraction with a molecular weight of 28,000 daltons. Endogenous phosphorylation required the presence of Mg2+ and was inhibited by Ca2+. A protein kinase inhibitor obtained from skeletal muscle inhibited the cyclicAMP-dependent phosphorylation. Escherichia coli alkaline phosphatase dephosphorylated the endogenous substrates. The level of phosphorylation found is severalfold higher than we have previously reported. A protein kinase, with its close association with the regulatory proteins, seems to be well suited to transmitting the message from the cyclic AMP to the regulatory proteins, a phenomenon that may influence the cardiac contractility via the troponin phosphorylation. The inhibitory effect of troponin on actomyosin might be changed by its state of phosphorylation.
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PMID:Phosphorylation of cardiac regulatory proteins by cyclic AMP-dependent protein kinase. 18 66

A procedure for the purification of cholesterol ester hydrolase from bovine adrenal cortical 105000 x g supernatant is described. Preincubation of a crude enzyme extract with [gamma-32P]ATP followed by purification resulted in the isolation of a phosphorylated preparation of cholesterol ester hydrolase. The phosphorylated cholesterol ester hydrolase appeared to be composed of 4 subunits, each having a molecular weight of 41000 +/- 280, only one of which may be phosphorylated. Preincubation of the crude enzyme preparation with [alpha-32P]ATP followed by purification did not produce a phosphorylated preparation of cholesterol ester hydrolase. Cyclic-AMP-dependent protein kinase, cyclic AMP, ATP and magnesium ions were required for activation of purified cholesterol ester hydrolase in vitro and the time course of activation closely paralleled the time course of phosphorylation of the enzyme. The addition of ATP, cyclic AMP and magnesium ions to the bovine adrenal cortical 105000 x g supernatant produced a 2.5-fold stimulation in cholesterol ester hydrolase activity. This stimulation was abolished if protein kinase inhibitor was added prior to the addition of ATP cyclic AMP and magensium ions. The addition of magnesium ions or calcium ions to a crude preparation of cholesterol ester hydrolase was found to inhibit activity; however the same additions made to a purified preparation of cholesterol ester hydrolase were not inhibitory. The decrease in cholesterol ester hydrolase activity on incubation with magnesium ion was accompanied by a loss of 32P radioactivity from the protein. Preincubation of a crude preparation of cholesterol ester hydrolase with alkaline phosphatase resulted in a deactivation of cholesterol ester hydrolase. It is suggested that bovine adrenal cortex cholesterol ester hydrolase is activated by a phosphorylation catalysed by a cyclic-AMP-dependent protein kinase. Deactivation of cholesterol ester hydrolase is accomplished by dephosphorylation catalysed by a phosphoprotein phosphatase, dependent on magnesium or calcium ions.
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PMID:Purification and control of bovine adrenal cortical cholesterol ester hydrolase and evidence for the activation of the enzyme by a phosphorylation. 18 99


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