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)

Small cultures of human amniotic cells were preincubated for 24 h. Human prolactin was then added to the medium. After a further short period of incubation the tubes were chilled, the medium removed and the cells rinsed with saline. The tubes then received cold Tris-sucrose and were frozen, to disrupt the cells. After thawing, adenosine triphosphatase (ATPase) and p-nitrophenyl phosphatase (PNPase) were measured. Buffer was added containing either ATP or PNP and the tubes were incubated for 30 min. Inorganic phosphate released from ATP and p-nitrophenol was measured spectrophotometrically. Prolactin stimulated both enzyme activities. The ATPase log dose-response curve was linear between approximately 12.5 and 200 mIU/l. It was inhibited by ouabain. Isobutyl-1-methylxanthine inhibited the ATPase but not the alkaline phosphatase activity. One of these human amniotic cell enzymes may provide the basis for a sensitive bioassay for human prolactin.
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PMID:Enzyme activation of human prolactin: a potential basis for a bioassay. 247 90

The effect of matrix components extracted Bovine periodontal ligament (PDL) on cell proliferation and alkaline phosphatase activity of cultured human periodontal ligament fibroblast (HPLF) were examined in order to understand the cell-tissue interaction of periodontal ligament. Bovine PDL tissue was sequentially extracted with 0.05 M Tris HCl buffer, pH 7.4, containing 1M NaCl or 4M GdmCl. After seeding 24 hours, the cultured HPLF were exposed to the extracts for two through eight days. Nine days after seeding, HPLF indicated four times high activity on ALP and 1.6 times the amount of total protein than those of control (without extract), while DNA synthesis increased only 1.2 times. On the contrary, the NaCl extract depressed the ALP activity of HPLF. The GdmCl extract enhanced both the total protein and ALP activity in dose-dependently. The ALP increasing activity of GdmCl extract on HPLF is stable to heat (78 degrees C, 20 min) and collagenase treatment but partially inactivated by trypsin digestion. Since the GdmCl extract also induced colony formation of NRK-49F cell in soft agarose, it was suggested that the extract contain EGF and TGF-beta like factor. Molecular size of this factor was estimated as 20-50Kd using Sepharose CL-6B gel chromatography. Furthermore, this factor from Sepharose CL-6B were separated into two forms by ion exchange CM-Sepharose column chromatography. Purified preparation from reversed phase column chromatography contained 14Kd, 15Kd, 17Kd, 20Kd, 28Kd40Kd, and 46Kd components on SDS-PAGE. This factor may accumulate in extracellular matrix, and may play a role of cell-tissue interaction and homeostasis in periodontal ligament.
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PMID:[Biochemical study on the TGF-beta like growth factor derived from bovine periodontal ligament]. 248 40

Saito et al recently reported that the alkaline phosphatase (ALPase) of human periodontal ligament fibroblasts (HPLF) showed remarkably high activity which was similar, but not identical phenotype, to that present in osteoblasts, and suggested that HPLF could be termed as "osteoblastic fibroblast." The present study attempts to explore the ALPase synthesized on HPLF in relation to 1,25(OH)2D3. These HPLF were obtained by the explantation method and then subcultured in D-MEM containing 2 mg FCSP/ml, 50 micrograms ascorbic acid/ml and penicillin/streptomycin after trypsinization. The HPLF were inoculated at a cell density of 1.25 x 10(4) cells/cm2 in culture wells. After 24hr, the HPLF were treated every two days for 7 days with 0.5-10nM 1,25 (OH)2D3. Then, ALPase activity, DNA and protein contents were assayed by the methods using p-nitrophenylphosphate, diaminobenzoic acid and Coomassie Brilliant Blue, respectively. Also, ALPase was prepared from the confluent HPLF incubated with 5 nM 1,25 (OH)2D3 for 12 days, and digested with and without trypsin. The crude ALPase which was solubilized with 10mM Tris-HCl, pH 7.4 containing 0.2 mM MgCl2 and 0.1% NP-40 was applied to 5-15% gradient SDS-PAGE and stained with beta-naphththylacid phosphate and First Blue BB salt in 60 mM borate buffer pH 9.7. The cell growth which was assayed by DNA contents and the incorporation of 3H-thymidine was decreased by 1,25(OH)2D3. On the other hand, ALPase activity was increased approximately 3.6 fold at 6 day by the addition of 5 nM 1,25(OH)2D3. From the separation of ALPase activity on SDS-PAGE, 110 K and 120-130 K ALPase were identified. The 110 K ALPase, which was not changed by 1,25(OH)2D3, was converted to 100K, releasing 10K peptide after trypsin treatment. This 110K ALPase might be tightly associated with cell membrane structure. The 120-130K ALPase was remarkably increased by 1,25(OH)2D3 on SDS-PAGE and completely digested with trypsin. The ALPase in the cultured HPLF might be located not only on the plasma membrane but also in the extracellular matrix. Therefore, 1,25(OH)2D3 may regulate the cell cycle and also the gene expression of ALPase of HPLF.
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PMID:[Biochemical study of human periodontal ligament fibroblasts--1,25 (OH)2D3 dependent alkaline phosphatase]. 248 52

Phosphorylated rabbit cardiac alpha alpha-tropomyosin has been prepared either enzymatically (Montgomery, K., and Mak, A.S. (1984) J. Biol. Chem. 259, 5555-5560) or by fractionation of the phosphorylated and nonphosphorylated forms on a Mono Q column in 9 M urea, 50 mM Tris, pH 8.0. Although the phosphorylated and nonphosphorylated forms showed no difference in their F-actin binding properties, the phosphorylated protein had substantially higher viscosities at low ionic strengths, indicating a greater propensity for head-to-tail interaction. Similar measurements showed the strengthening of this interaction by whole troponin to be substantially reduced by phosphorylation even though the binding of whole troponin and troponin T to tropomyosin was demonstrated by affinity chromatography to be, if anything, strengthened by phosphorylation. In a reconstituted actin (4 microM) plus myosin subfragment 1 ATPase assay (50 mM ionic strength), significantly higher activities over a range (1 to 8 microM) of subfragment 1 concentrations were observed with phosphorylated tropomyosin compared with the nonphosphorylated protein. In the fully reconstituted system with troponin, there was no significant difference in the inhibition of ATPase in the absence of Ca2+. However, in its presence, the activities were appreciably increased with the phosphorylated tropomyosin compared to those with the nonphosphorylated form. These differences were eliminated by treatment of the phosphorylated tropomyosin with alkaline phosphatase. This is the first demonstration of an effect of phosphorylation on the functional properties of tropomyosin.
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PMID:Effect of phosphorylation on the interaction and functional properties of rabbit striated muscle alpha alpha-tropomyosin. 252 28

The function of aspartic acid residue 101 in the active site of Escherichia coli alkaline phosphatase was investigated by site-specific mutagenesis. A mutant version of alkaline phosphatase was constructed with alanine in place of aspartic acid at position 101. When kinetic measurements are carried out in the presence of a phosphate acceptor, 1.0 M Tris, pH 8.0, both the kcat and the Km for the mutant enzyme increase by approximately 2-fold, resulting in almost no change in the kcat/Km ratio. Under conditions of no external phosphate acceptor and pH 8.0, both the kcat and the Km for the mutant enzyme decrease by approximately 2-fold, again resulting in almost no change in the kcat/Km ratio. The kcat for the hydrolysis of 4-methyl-umbelliferyl phosphate and p-nitrophenyl phosphate are nearly identical for both the wild-type and mutant enzymes, as is the Ki for inorganic phosphate. The replacement of aspartic acid 101 by alanine does have a significant effect on the activity of the enzyme as a function of pH, especially in the presence of a phosphate acceptor. At pH 9.4 the mutant enzyme exhibits 3-fold higher activity than the wild-type. The mutant enzyme also exhibits a substantial decrease in thermal stability: it is half inactivated by treatment at 49 degrees C for 15 min compared to 71 degrees C for the wild-type enzyme. The data reported here suggest that this amino acid substitution alters the rates of steps after the formation of the phospho-enzyme intermediate.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Alteration of aspartate 101 in the active site of Escherichia coli alkaline phosphatase enhances the catalytic activity. 268 45

The Dictyostelium discoideum alkaline phosphatase was investigated kinetically in an attempt to elucidate its mechanism of action. Analysis of the hydrolysis of p-nitrophenyl phosphate by stopped-flow spectrophotometry revealed biphasic kinetics, suggesting a double displacement enzyme mechanism. Furthermore, Tris stimulated activity in an uncompetitive manner, a result that was consistent with this interpretation. The enzyme was inhibited reversibly by phosphate at low ionic strength, but the inhibition was irreversible at high ionic strength and the latter effect was enhanced at alkaline pH values. These results indicate that high ionic strength and alkaline pH conditions bring about a conformational change that renders the enzyme susceptible to irreversible inhibition by phosphate.
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PMID:Studies on the mechanism of action of the alkaline phosphatase from Dictyostelium discoideum. 270 77

The C-terminal two-thirds of the rat liver ATP synthase beta subunit has been overexpressed and exported to the Escherichia coli periplasm under the direction of the alkaline phosphatase (phoA) promoter and leader peptide. The processed soluble protein contains the 358 amino acids from glutamate 122 to the rat liver beta C-terminal serine 479, including all the regions that have been predicted by chemical and genetic modification studies to be involved in nucleotide, Pi, and Mg2+ binding. Through a simple sequence of Tris/EDTA/lysozyme treatment, osmotic lysis, and alkaline pH washes, the processed beta subunit fragment can be prepared in greater than 95% purity and at a yield of greater than 20 mg/liter of culture. It interacts with 2'(3')-O-(2,4,6-trinitrophenyl) adenosine 5'-triphosphate (TNP-ATP) which exhibits a strong enhancement of fluorescence upon binding. A similar enhancement is observed upon interaction with TNP-ADP. Enhancement observed with both TNP-nucleotides is markedly reduced by prior addition of either ATP or ADP and almost completely prevented by the ATP synthase inhibitor 7-chloro-4-nitrobenz-2-oxa-1,3-diazole. Both TNP-ATP and TNP-ADP bind at a stoichiometry of approximately 1 mol of nucleotide/mol of beta subunit fragment. Under the same conditions, TNP-AMP does not exhibit a fluorescence enhancement. This work demonstrates that, in the absence of interaction with other ATP synthase subunits, the rat liver beta subunit sequence from glutamate 122 to the C terminus exhibits no more than one readily detectable nucleotide binding domain. This success in producing a "functional" beta subunit fragment has significance for the pursuit of genetic and physical studies focused on the structure and function of the rat liver ATP synthase beta subunit.
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PMID:Mitochondrial ATP synthase. Overexpression in Escherichia coli of a rat liver beta subunit peptide and its interaction with adenine nucleotides. 290 92

Oligomycin-sensitive particulate ATPase (MB ATPase) from L. donovani promastigotes was solubilized by chloroform treatment. Polyacrylamide gel electrophoresis revealed several protein bands, with the major one possessing ATPase activity. The solubilized enzyme had Mg2+-ATPase and Ca2+-ATPase but no K+-dependent alkaline phosphatase activity. The Mg2+-ATPase activity was stimulated by monovalent cations and was not sensitive to oligomycin. Hence it is referred to as F1 ATPase. It had optimum activity at pH 7.6 and 30 degrees C. The Arrhenius plot for MB ATPase was biphasic with activation energies (Ea) of 16.2 and 3.4 kcal mol-1, while F1 ATPase exhibited a linear plot with Ea = 10.1 kcal mol-1. Lineweaver-Burk plots were biphasic with Km values of 0.17 and 1.25 mM for MB ATPase and 0.18 and 1.33 mM for F1 ATPase. The enzyme could be preserved at -15 degrees C in Tris-SO2-(4)-EDTA-ATP-glycerol (t1/2 = 20 days).
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PMID:Solubilization and kinetic characterization of mitochondrial adenosine triphosphatase from Leishmania donovani promastigotes. 297 May 89

The catalytic properties of the HhaII restriction endonuclease were studied using plasmid pSK11 DNA containing a single 5'-G-A-N-T-C HhaII cleavage site as substrate. Reactions were followed by two methods: 1) gel electrophoretic analysis of nicked circular and linear DNA products, or 2) release of 32P-labeled inorganic phosphate from specifically labeled HhaII sites in a reaction coupled with bacterial alkaline phosphatase. The enzyme is optimally active at 37 degrees C in 10 mM Tris-HCl (pH 9.1) and 4-10 mM MgCl2 without added NaCl. Activity is stabilized by the presence of 2-mercaptoethanol and 0.2% Triton X-100 or 50 microgram/ml bovine serum albumin. At enzyme concentrations below 10 nM and using pSK11 as substrate, initial kinetic rates were dependent on the order of mixing of reactants. A lag of 3-4 min was observed if enzyme or substrate was added last. Preincubation of substrate and enzyme followed by initiation of the reaction with MgCl2 or preincubation of the enzyme with nonspecific DNA followed by initiation with substrate eliminated or reduced the lag, respectively, and speeded up the reactions. Under a wide range of reaction conditions, nicked pSK11 DNA accumulated early, while linear molecules appeared later, suggesting that HhaII cleaves one strand at a time in separate binding events. The apparent Km for covalently closed pSK11 DNA molecules was approximately 17 nM, and the turnover number for the conversion of covalent to nicked sites was 1.1 single strand scissions/min. Pre-steady state kinetic analysis indicated that cleavage of the first phosphodiester bond in a site is first order with a rate constant of about 0.8 min-1, while cleavage of the second phosphodiester bond is first order with a rate constant of about 0.2 min-1.
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PMID:Catalytic properties of the HhaII restriction endonuclease. 299 12

Purified isoenzymes of human alkaline phosphatase from placenta, intestine and liver were investigated as catalysts for phosphotransferase activity, using the phosphoacceptors Tris, 2-amino-2-methyl-1-propanol, 2-amino-2-methyl-1,3-propanediol, diethanolamine, 2-(ethylamino)ethanol, ethanolamine, and N-methyl-D-glucamine. All of the compounds supported phosphotransferase catalysis, conforming to saturation kinetics. There was little difference among the isoenzymes with respect to Km values of the acceptors, but the liver form was the most efficient (highest Vmax/Km) in forming phosphoacceptors; it was also the most efficient (highest Vamax/Ka) when the phosphoacceptors were considered as activators. At Vmax the isoenzymes differed little in their support of phosphotransferase activity relative to phosphohydrolysis, although the intestinal enzyme tended to be the poorest. The two best acceptors were diethanolamine, providing the highest phosphotransferase velocity, and 2-(ethylamino)ethanol, having the lowest Km. The phosphoaceptors that bound Zn2+ tightly did not function well in the phosphotransferase reaction, and vice versa. However, temporal assessment of the phosphohydrolytic and phosphotransferase activities during removal of Zn2+ from the enzyme with 1,10-phenanthroline revealed no evidence of a special role for Zn2+ in the latter activity.
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PMID:Phosphotransferase activity of human alkaline phosphatases and the role of enzyme Zn2+. 303 34


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