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 absorbance of an alkaline solution of 4-nitrophenyl phosphate is a function of temperature. Quantitative evaluation of this phenomenon indicates that it (a) depends on the concentration of the compound and is independent of source, buffer concentration, and pH above 9.0; (b) is reversible; (c) is not a result of alkaline hydrolysis or 4-nitrophenol contamination; and (d) correlates with a temperature-induced shift of its absorbance spectrum. The phenomenon may represent a potential analytical problem in methods for alkaline phosphatase in which this compound is the substrate. If thermal equilibrium is not reached and maintained during an alkaline phosphatase assay, the thermochromic response will be included in the measured rate. The magnitude of this error depends on the thermal response and control characteristics of each particular instrument and the reaction conditions under which such an analysis is performed.
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PMID:Temperature dependence of the absorbance of alkaline solutions of 4-nitrophenyl phosphate--a potential source of error in the measurement of alkaline phosphatase activity. 1 64

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

We used paired-ion high-performance liquid chromatography to determine the 4-nitrophenol content of 4-nitrophenyl phosphate, a substrate for alkaline phosphatase analysis. This was done on a reversed-phase column with a mobile phase of methanol/water, 45/55 by vol, containing 3 ml of tetrabutylammonium phosphate reagent per 200 ml of solvent. At a flow rate of 1 ml/min, 4-nitrophenol was eluted at 9 min and monitored at 404 nm; 4-nitrophenyl phosphate was eluted at 5 min and could be monitored at 311 nm. Samples of 4-nitrophenyl phosphate obtained from several sources contained 0.3 to 7.8 mole of 4-nitrophenol per mole of 4-nitrophenyl phosphate.
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PMID:4-Nitrophenol in 4-nitrophenyl phosphate, a substrate for alkaline phosphatase, as measured by paired-ion high-performance liquid chromatography. 20 Mar 79

Serum alkaline phosphatase estimations by the Selected Method [Clin. Chem. 21, 1988 (1975)] are very sensitive to small errors in the wavelength setting of the spectrophotometer. With a setting error as small as 3 nm, results can be too low by as much as 23%. The product of the reaction, 4-nitrophenol, can be prepared in very pure form and can be used to check both the wavelength and absorbance accuracy of a spectrophotometer. The molar absorptivity for 4-nitrophenol obtained in the instrument being used should be used in calculating alkaline phosphatase activities.
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PMID:Factors affecting measurement of total alkaline phosphatase activity in human serum, especially wavelength accuracy. 65 84

A procedure for determination of serum alkaline phosphatase activity (EC 3.1.3.1) in diethanolamine (DEA) buffer with an AutoAnalyzer II apparatus was designed. The buffer used was 1.0 mol/l DEA-HC buffer, pH 9.8 at 37 degree C, containing 0.5 mmol/l of MgCl2 and 10 mmol/l of substrate 4-nitrophenyl-phosphate. The reaction time was about 3 min at 37 degree C. The enzyme activity (U/l) was calculated by determining the amount of 4-nitrophenol formed in reaction. A sampling rate of 70 samples per hour can be used with good linearity up to 1000 U/l. The results obtained by the new continuous-flow system were compared with those measured by the kinetic method according to the Scandinavian recommendation (10). A close correlation between the two methods was observed.
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PMID:A continuous-flow method for the determination of the activity of serum alkaline phosphatase in diethanolamine buffer. 115 23

On 120 patients, during normal pregnancy, from the 17th to the 42nd week of pregnancy, 372 heat labile alkaline phosphatase estimations were carried out by means of the 4-nitrophenol method. In addition to that, after incubation of sera at 65 degrees C for 30 minutes, the activity of the heat stable placental isoenzyme was checked. With progressing pregnancy, the heat stable fraction rises significantly and the heat labile fraction of total alkaline phosphatase increases slightly. There is a correlation between the readings of the two fractions. In 169 cases, the total urinary oestrogen output correlates also with the heat stable alkaline phosphatase.
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PMID:[Behavior of alkaline phosphatase in serum during pregnancy. I. Normal pregnancy]. 121 Aug 74

1. Effect of intracellular ATP on Cl- current (ICl) mediated by the GABA (gamma-aminobutyric acid) receptor subtype, GABAA, was studied in dissociated nucleus tractus solitarii (NTS) neurones using the whole-cell mode of patch clamp. A concentration-jump technique termed 'Y tube' was used to rapidly apply agents externally. Dissociated neurones were obtained from 1- to 3-week-old rats. 2. When the patch-pipette solution contained 2 mM-ATP, the amplitude of ICl elicited by 10(-5) M-GABA did not show any time-dependent decrease (apparent run-down), for more than 60 min after the initial recording. In the presence of ATP, the half-maximum concentration (KD) and Hill coefficient calculated from the GABA concentration-response curve were 9.12 microM and 1.47, respectively. 3. In the absence of intracellular ATP, the amplitude of GABA-induced ICl decreased with time. The relative peak amplitudes after 20 and 60 min from the initial recording were 0.40 +/- 0.09 (n = 11) and 0.16 +/- 0.05 (n = 8) with respect to the initial response. 4. Removal of Mg2+ from the internal solution induced run-down of the GABA response even in the presence of 2 mM-intracellular ATP, suggesting that both intracellular ATP (2 mM or more) and Mg2+ are necessary to prevent run-down of the GABA response. 5. Activation of dephosphorylation processes by alkaline phosphatase (100-200 microM) did not affect the GABA response in neurones perfused with internal solution containing 2 mM-ATP and 3 mM-Mg2+. Blocking the dephosphorylation process by okadaic acid, a phosphatase inhibitor, did not prevent the run-down of the GABA response. 6. Calcium influxes passing through both the voltage-dependent L-type Ca2+ channel and the glutamate receptor-operated cation channel did not affect ICl induced by GABA. 7. GABA-induced ICl was also maintained by adding 2 mM-ADP or ATP gamma S (adenosine-5'-O-3-thiotriphosphate) to the internal solution containing Mg2+. Addition of 2 mM-adenosine, AMP, cyclic AMP, AMP-PNP (adenylimido-diphosphate) or ADP beta S (adenosine-5'-O-2-thiodiphosphate) to the internal solution did not prevent the run-down of the GABA response even in the presence of 3 mM-intracellular Mg2+. Based on the chemical specificity of these ATP analogues, it is suggested that there is an ATP-sensitive binding site (ATP receptor) in the cytoplasmic side of the cell membrane.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Direct modulation of GABAA receptor by intracellular ATP in dissociated nucleus tractus solitarii neurones of rat. 138 52

In microsomes obtained from mouse pancreatic islets, the Mg complex of adenosine 5'-triphosphate (MgATP) increased the dissociation constant (KD) for binding of [3H]glibenclamide by sixfold. In the presence of Mg2+, not only ATP but also adenosine 5'-0-(3-thiotriphosphate) (ATP gamma S), adenosine 5'-diphosphate (ADP), guanosine 5'-triphosphate (GTP), guanosine 5'-diphosphate (GDP), guanosine 5'-0-(3-thiotriphosphate) (GTP gamma S) and guanosine 5'-0-(2-thiodiphosphate) (GDP beta S) inhibited binding of [3H]glibenclamide. These effects were not observed in the absence of Mg2+. Half maximally effective concentrations of the Mg complexes of ATP, ADP, ATP gamma S and GDP were 11.6, 19.0, 62.3 and 90.1 mumol/l, respectively. The non-hydrolyzable analogues adenosine 5'-(beta,gamma-imidotriphosphate) (AMP-PNP) and guanosine 5'-(beta,gamma-imidotriphosphate) (GMP-PNP) did not alter [3H]glibenclamide binding in the presence of Mg2+, MgADP acted much more slowly than MgATP and both MgADP and MgGDP did not inhibit [3H]glibenclamide binding when the concentrations of MgATP and MgGTP were kept low by the hexokinase reaction. Development of MgATP-induced inhibition of [3H]glibenclamide binding and dissociation of [3H]glibenclamide binding occurred at similar rates. However, the reversal of MgATP-induced inhibition of [3H]glibenclamide binding was slower than the association of [3H]glibenclamide with its binding site. Exogenous alkaline phosphatase accelerated the reversal of MgATP-induced inhibition of [3H]glibenclamide binding. MgATP enhanced displacement of [3H]glibenclamide binding by diazoxide. The data suggest that sulfonylureas and diazoxide exert their effects by interaction with the same binding site at the sulfonylurea receptor and that protein phosphorylation modulates the affinity of the receptor.
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PMID:Phosphate and thiophosphate group donating adenine and guanine nucleotides inhibit glibenclamide binding to membranes from pancreatic islets. 190 88

X-ray microanalysis has been used to characterize the enzyme activity hydrolyzing the ATP analogue 5'-adenylylimidodiphosphate (AMP-PNP) in taste bud cells. Rabbit foliate papillae fixed with paraformaldehyde and glutaraldehyde were incubated cytochemically with AMP-PNP as the substrate and lead ion as capture agent. The reaction product which appeared on the microvilli of taste bud cells was examined using an energy dispersive X-ray microanalyzer connected to an analytical electron microscope. The X-ray spectrum thus obtained was compared with that obtained from the product obtained from the demonstration of ATPase activity. Comparison of the phosphorus/lead ratios in the two products showed that twice as much phosphorus was released from an AMP-PNP molecule by the activity in question compared with that released from an ATP molecule by ATPase activity. This indicates that the enzyme hydrolyzes AMP-PNP into AMP and imidodiphosphate and that the enzyme is adenylate cyclase or ATP pyrophosphohydrolase, which possesses a similar hydrolytic property, but not ATPase or alkaline phosphatase, which hydrolyzes AMP-PNP into ADP-NH2 and orthophosphate. This paper provides an example of the use of X-ray microanalysis as a tool for enzyme distinction. The method is applicable to a variety of enzymes and tissues.
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PMID:Identification of 5'-adenylylimidodiphosphate-hydrolyzing enzyme activity in rabbit taste bud cells using X-ray microanalysis. 216 24

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


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