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 kinetic study of the C2+ ATPase activity of lymphocyte plasma memebranes allowed some properties of this enzyme to be evidenced. The Ca2+-activated hydrolysis of ATP is independent of a non-specific alkaline phosphatase. The substrate of the ATPase activity is the chelate Ca2+- ATP. Mg2+ may substitute for Ca2+ both as chelating ion and as activating ion. Several results suggest that we have only one ATPase, activated either by Ca2+-, or by Mg2+ with less efficiency; both chelates hve the same Km; pH values for maximum activity and transition temperatures are identical; the effects of free ions are also the same, activation at low concentration and inhibition at high concentration.
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PMID:[Kinetics of Ca 2+ or Mg 2+ activated ATPase from lymphocyte plasma membranes]. 0 56

The histrochemistry of the adrenal glands was studied in four adult male marmosets (two Callithrix jacchus and two Callithrix penicillata). It was impossible to demonstrate any reactivity to UDPG-GT, ADH, alanyl aminopeptidase, leucine aminopeptidase, xilitol (NAD-dependent) dehydrogenase, beta-glucuronidase and aryl-sulfatase in these glands. Total phosphorylase was found in scattered cells of the glomerulosa and adjacent outer fasciculata of one C. penicillata. The dehydrogenases (LDH, G-6-PDH,6-PGDH, NADPH2-TR,ICDH,SDH,NADH2-TR, alpha-GPDH, beta-OHBDH) as well as the hydrolases (except alkaline phosphatase, ATPase, and acetylcholinesterase) showed a stonger reactivity in the cortical part. Some hydrolases (naphthol acetate esterase, acid phosphatase) and cytochrome oxidase were less reactive in the zona glomerulosa, where the dehydrogenases were more abundant. The outer fasciculata and the reticularis also showed a strong dehydrogenase reactivity.
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PMID:Histochemical studies on the adrenal glands of the marmosets (Callithrix jacchus and Callithrix penicillata). 0 44

Some of the characteristics of the pyrophosphatase and ATPase activities studied in isolated cartilage matrix vesicles were found to be similar to those already reported for the solubilized and purified bone alkaline phosphatase. Thus, the pH optimum of the pyrophosphatase activity responded similarly to changes in the concentration of Mg2+, Ca2+, and PPi. Further, the ATPase activity was not activated by Ca2+ in the presence of an optimal Mg2+ concentration. It is proposed that a function of the alkaline phosphatase of matrix vesicles in vivo is to hydrolyze the substrates PPi, ADP, and ATP, which are known inhibitors of calcium phosphate precipitation.
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PMID:Pyrophosphatase and ATPase of isolated cartilage matrix vesicles. 1 78

Free-flow electrophoresis was used to subfractionate membrane vesicles from calf thymocyte plasma membranes. The fractionation resulted in a separation of vesicle populations bearing four different enzymes: alkaline nitrophenyl-phosphatase (orthophosphoric-monoester phosphohydrolase (alkalin optimum) EC 3.1.3.1), gamma-glutamyltransferase (EC 2.3.2.2), (Mg2+ + Na+ + K+)-ATPase (ATP phosphohydrolase, EC 3.6.1.3) and acyl-CoA:lysophosphatidylcholine acyltransferase (acyl-CoA:1-acylglycero-3-phosphocholine-O-acyltransferase, EC 2.3.1.23). The specific content of cholesterol and total phospholipid coincided with the distribution of membrane-bound protein. However, vesicles migrating towards the cathode had a higher molar ratio of cholesterol to phospholipid (0.75) compared to those migrating to the anode (0.55). Sodium dodecyl sulphate-gel electrophoresis of pooled vesicle fractions also demonstrates distinct differences in their protein pattern. Electron-micrographic thin sections show that the vesicle populations have a similar morphology and size distribution. These results are discussed in terms of heterogeneity of the original thymocytes, contamination with intracellular membranes and a heterogeneous structure of the plasma membrane.
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PMID:Fractionation of membrane vesicles. II. A method for separation of membrane vesicles bearing different enzymes by free-flow electrophoresis. 2 91

The activity of calcium-stimulated ATPase (E.C. 3.6.1.3) in homogenates of the secretory enamel organ of rat incisors was studied biochemically. ATP hydrolysis was estimated from the amount of inorganic phosphate liberated. An analysis of the total degradation of ATP was initially performed to ensure that the enzyme assays pertained to the original substrate, ATP, and were not influenced by reaction products formed. Standard incubations were run in tris-maleate buffer, pH 8.2, with 3 mM ATP, 3 mM Ca2+ and 0.5 mM R 8231 at 37 degrees C. The presence of R 8231 was necessary to inhibit nonspecific alkaline phosphatase. The calcium-stimulated ATPase was completely inhibited when heated at 55-60 degrees C for 5 min. The pH optimum was found to be 8.2. The hydrolysis was substantially dependent on Ca2+ and was fastest when the ATP:Ca2+ ratio was 1:1. High substrate concentrations inhibited the hydrolysis. The addition of 1 mM Zn2+ and Ni2+ to the incubation medium markedly inhibited the hydrolysis as did, though less strongly, p-hydroxymercuribenzoate, oligomycin, EDTA and ruthenium red. l-Cysteine, mercaptoethanol, iodoacetic acid and sodium azide were without effect. F- was without effect unless added to a final concentration above 15 mM to media where Ca2+ had first been allowed to react with ATP.
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PMID:Calcium-stimulated ATPase activity in homogenates of the secretory enamel organ in the rat. 2 89

The interpretation of the morphological features of alcoholic hepatitis is discussed in terms of a comparison with the results of an ultrastructural and histoenzymological study of the liver biopsies of nine patients. In these patients liver biopsies were performed in the initial stage of the illness and fifteen days after five were re-biopsied, when the clinical and biological signs were improved. The correlations between morphological and biological data were good, especially for the levels of serological and histoenzymological alkaline phosphatase and gamma-glutamyltranspeptidase evaluations. However, when histological appearances had returned to normal, after two weeks of abstinence from alcohol several histological and ultrastructural features of the initial hepatitis persisted. The presence of evolving cirrhosis was a contributing factor to the severity of the changes seen. Morphologically, apart from the changes due to chronic alcoholic intoxication (steatosis, mitochondrial alteration), the hepatitic lesions comprise Mallory's bodies, cytoplasmic oedema and mitochondrial swelling. Cholestasis was invariably present. Histo-enzymologically there was a reduction in ATPase activity suggesting a metabolic failure in the energy producing pathways. In addition, in the periphery of lobules an active cirrhotic process was present, with tubular de-differentiation of hepatocytes and an increase in gamma-glutamyltranspeptidase on the cytoplasmic membrane. Because of the absence of any topographical relationship between hepatitis and cirrhosis, the presence of lymphocytes in the neighbourhood of the ductules suggested an indirect relationship between both processes, perhaps an autoimmune response initiated by Mallory's bodies.
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PMID:[The hepatocyte in acute alcoholic hepatitis. Histoenzymological and ultrastructural analysis (author's transl)]. 3 Oct 27

Kinetic parameters for the hydrolysis of a number of physiologically important phosphoesters by purified human liver alkaline phosphatase have been determined. The enzyme was studied at pH values of 7.0 to 10.0. The affinity of the enzyme for the compounds was determined by competition experiments and by their direct employment as substrates. Phosphodiesters and phosphonates were not hydrolysed but the latter were inhibitors. Calcium and magnesium ions inhibited the hydrolysis of ATP and PP1 and evidence is presented to show that the metal complexes of these substrates are not hydrolysed by alkaline phosphatase. A calcium-stimulated ATPase activity could not be demonstrated for the purified enzyme or the enzyme in the presence of a calcium-dependent regulator protein. Nevertheless, the influence of magnesium and calcium ions on the ATPase activity of alkaline phosphatase means that precautions must be taken when assaying for Ca2+-ATPase in the presence of alkaline phosphatase. The low substrate Km values and the hydrolysis which occurs at pH 7.4 mean that the enzyme could have a significant phosphohydrolytic role. However, liver cell phosphate concentrations, if accessible to the enzyme, are sufficient to strongly inhibit this activity.
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PMID:Phosphoester specificity of purified human liver alkaline phosphatase. 3 70

Purified chondrocytic alkaline phosphatase (orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1) from bovine fetal epiphyseal cartilage hydrolyzes a variety of phosphate esters as well as ATP and inorganic pyrophosphate. Optimal activities for p-nitrophenyl phosphate, ATP and inorganic pyrophosphate are found at pH 10.5, 10.0 and 8.5, respectively. The latter two substrates exhibit substrate inhibition at high concentrations. p-Nitrophenyl phosphate demonstrates decreasing pH optima with decreasng substrate concentration. Heat inactivation studies indicate that both phosphorolytic and pyrophosphorolytic cleavage occur at the same site on the enzyme. Mg2+ (0.1-10.0 mM) and Mn2+ (0.01-0.1 mM) show a small stimulation of p-nitrophenyl phosphate-splitting activity at pH 10.5. Levamisole, Pi, CN-, Zn2+ and L-phenylalanine are all reversible inhibitors of the phosphomonoesterase activity. Pi is a competitive inhibitor with a Ki of 10.0 mM. Levamisole and Zn2+ are potent non-competitive inhibitors with inhibition constants of 0.05 and 0.04 mM, respectively. The chondrocytic alkaline phosphatase is inhibited irreversibly by Be2+, EDTA, EGTA, ethane-1-hydroxydiphosphonate, dichloromethane diphosphonate, L-cysteine, phenyl-methylsulfonyl fluoride, N-ethylmaleimide and iodoacetamide. NaCL, KCL and Na2SO4 at 0.5-1.0 M inhibit the enzyme. At pH 8.5, the cleavage of inorganic pyrophosphate (pyrophosphate phosphohydrolase, EC 3.6.1.1) by the chondrocytic enzyme is slightly enhanced by low levels of Mg2+ and depressed by concentrations higher than 1mM. Ca2+ show only inhibition. Similar effects of Mg2+ and Ca2+ on the associated ATPase (ATP phosphohydrolase, EC 3.1.6.3) activity were observed. Arrhenius studies using p-nitrophenyl phosphate and AMP as substrates have accounted for the ten-fold difference in V in terms of small differences in both the enthalpies and entropies of activation which are 700 cal/mol and 2.3 cal/degree per mol, respectively.
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PMID:Enzymatic characterization of the chondrocytic alkaline phosphatase isolated from bovine fetal epiphyseal cartilage. 4 Jun 3

Coronal odontoblast-predentin tissue was taken from intact teeth and from teeth with carious lesions of varying depths, and the samples (20, 200 x g, saline-soluble fractions) were studied for their ability to hydrolyze adenosine triphosphate (ATP) and phosphoserine. A significantly higher rate of ATP hydrolysis at pH 9.8 was detected in enamel caries and a significantly lower rate in advanced caries than in intact teeth. The rates of the hydrolysis of phosphoserine at pH 9.8 did not differ between the various tooth groups, and the only clear trend indicating elevated enzyme activity was seen in the group of initial dentin caries. The ATP and phosphoserine hydrolysis at pH 9.8 were considered to have been due to the nonspecific alkaline phosphatase (EC 3.1.3.1) activity. In the presence of both levamisole and ouabain, maximal enzyme-dependent ATP hydrolysis was observed at pH 7.9. The remaining ATP-cleaving activity was thought to have been due to the Ca2+Mg2+-dependent ATPase (EC 3.6.1.3). The Ca2+Mg2+-dependent ATPase activities at pH 7.9 remained at constant levels in both the intact and carious groups. The parameters studied in vitro were thought to reflect changes in the mineralization rate of reparative dentin as a response to caries in vivo.
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PMID:The hydrolysis rates of ATP and phosphoserine in the odontoblast-predentin region of intact and carious human teeth. 4 67

Plasma membranes from normal, full-term human placental trophoblast have been isolated by a new procedure. The method depends upon isopycnic zonal centrifugation using linear sucrose/Ficoll density gradients. Enrichment of plasma membrane marker enzymes with respect to trophoblast homogenate is found in two distinct peaks (designated B and D) of the fractionated effluent recovered from the rotor. Fraction B is enriched with membrane-bound alkaline phosphatase and 5'-nucleotidase, but not with (Na+, K+)-ATPase of F(-)-stimulated adenylate cyclase. It is suggested that this material is derived from the maternal-facing microvillous plasma membrane. Fraction D, enriched with (Na+, K+)-ATPase, F(-)-stimulated adenylate cyclase and, to a smaller extent, with 5'-nucleotidase and alkaline phosphatase is, by exclusion, proposed to be derived from the fetal-facing basal plasma membrane. Both plasma membrane fractions are shown to be free of appreciable contamination, using specific markers for endoplasmic reticulum, mitochondria, nuclei and lysosomes. The separation of the two membrane fractions is shown to depend both upon these membranes forming closed vesicles during homogenization and upon the buoyant densities of such vesicles differing in such a way that microvillous plasma membranes band at a lower density than basal plasma membranes. No separation of the membranes is achieved in gradients in which the vesicles are collapsed.
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PMID:Separation of the microvillous (maternal) from the basal (fetal) plasma membrane of human term placenta: methods and physiological significance of marker enzyme distribution. 9 48


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