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 ultracytochemical localization of eight hydrolytic enzymes (TMPase, 5'-NPase, TPPase, TTPase, Mg++-ATPase, Ca++-ATPase, ALPase and K+-NPPase) and one oxidative enzyme (MAO) was determined in rat brain capillary endothelial cells. In the somal plasma membrane, the enzymatic activity was mainly located in the antiluminal plasma membrane. This finding was appropriate for enzymes possessing the optimal pH at alkaline ranges, except for alkaline phosphatase. Most enzymes investigated showed a positive reaction on the pinocytotic vesicles of capillary endothelial cells. Differences in the intensity of the enzyme activities of the luminal and antiluminal plasma membranes may reflect the polarity in the capillary endothelial cells and relate to blood-brain barrier mechanisms.
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PMID:Ultracytochemical studies of capillary endothelial cells in the rat central nervous system. 632 56

The functional role of the alternating morphologic changes of the rat and hamster incisor ameloblasts at the stage of enamel maturation was investigated. Special attention was paid to the distribution of the intravenously injected horseradish peroxidase (HRP) throughout the ameloblastic layer. The ameloblasts at the stage of enamel maturation were divided into two groups with respect to their distal cell borders: ruffle-ended (RA) and smooth-ended ameloblasts (SA). In the ameloblastic layer, SA were distributed as several band-like structures (SA-bands) which ran transversely or obliquely along the distal surface of the ameloblastic layer. Intravenously injected HRP permeated the intercellular spaces of SA and reached the surface of the enamel, however it did not penetrate the distal junctions of RA. Five min after the injection, HRP was incorporated into the cytoplasmic vesicles of RA, while no incorporation was shown in SA. After 1 hr, however, HRP was incorporated into the incisal one-third of the ameloblasts in each SA-band. Acid phosphatase activity (p-nitrophenylphosphatase) was shown in the cytoplasmic vesicles, both in RA and SA. The most intense alkaline phosphatase activity was located on the ruffled border of RA, while no activity was detected on the unmodified apices of SA. Contact microradiography revealed a gradual increase of the radio opacity of enamel towards the incisal direction independent of the alternating changes of overlaying RA and SA. However, the fluorescence of injected tetracycline showed intense labelling at the portions of enamel which corresponded to RA. The portions of enamel being overlayed by SA were located in between such labelled areas and showed only faint fluorescence of tetracycline. These results suggest that, RA actively degrade, resorb and then digest the organic matrices of the enamel and also transport minerals into the enamel. It is also suggested that SA are formed from the RA which have become inactive metabolically and here the exhausted cytoplasmic organelles seem to be renewed and reactivated.
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PMID:Ultrastructural and cytochemical observations on the alternating morphologic changes of the ameloblasts at the stage of enamel maturation. 723 66

Synaptic vesicles isolated from bovine cerebral cortex were found to contain alkaline phosphatase activity towards p-nitrophenylphosphate and alpha-naphthyl phosphate, but not towards pyridoxal phosphate. The enzyme had an apparent molecular weight of 125,000 and co-purified with the synaptic vesicles in parallel with the specific neurotransmitter content and with the loss of contaminating components, whereas the major phosphatase which was present in the brain homogenate, with an apparent molecular weight of 140,000 purified away. The optimal pH for the enzyme activity on p-nitrophenylphosphate was 9.8. At this pH the activity was 33.4 nmol/mg protein/min, and the apparent Km value was 0.31 +/- 0.05 mM. The pH dependency of the synaptic vesicle phosphatase activity towards p-nitrophenylphosphate differed from that of the Ca2+/Mg2+-dependentt ATP hydrolysis by the synaptic vesicles. Upon mild digestion of lyzed vesicles with trypsin, phosphatase activity was reduced whereas the ATPase activity was retained suggesting that the phosphatase and the ATPase are two different enzymes. The phosphatase was reversibly inhibited by ethyleneglycol bis (aminoethyl ether) N,N'-tetracetic acid (EGTA) and activity was restored by the addition of an equimolar amount of CA2+. Magnesium ions could restore only 30% of the activity. The activity of the synaptic vesicle phosphatase was not affected by o-phenanthroline, zinc ion or by cAMP. Tetranitromethane inactivated the enzyme irreversibly, whereas phenylmethanesulfonylfluoride diisopropylfluorophosphate and p-hydroxymercurybenzoate inhibited the activity partially. The enzyme did not have a diesterase activity. Adenosine mono-, di- and triphosphate inhibited the p-nitrophenylphosphatase activity and were also hydrolyzed by the vesicle preparation. However, the different kinetic parameters obtained with the nucleotide as inhibitors or as substrates suggest that additional enzymes are involved in the hydrolysis of the adenine nucleotides in vesicle preparation.
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PMID:A calcium-stimulated alkaline phosphatase associated with synaptic vesicles. 741 49

Alkaline phosphatase activity was released up to 100% from the membrane by using 0.1 U of phosphatidylinositol-specific phospholipase C from B. thuringiensis. The M(r) of solubilized enzyme was 145,000 by Sephacryl S-300 gel filtration and 66,000 by SDS-PAGE, suggesting a dimeric structure. Solubilization of the membrane-bound enzyme with phospholipase C did not destroy its ability to hydrolyze p-nitrophenyl phosphate (PNPP) (264.3 mumol min-1 mg-1),ATP (42.0 mumol min-1 mg-1) and pyrophosphate (28.4 mumol min-1 mg-1). The hydrolysis of ATP and PNPP by solubilized enzyme exhibited "Michaelian" kinetics with K0.5 = 70 and 979 microM, respectively. For pyrophosphate, K0.5 was 128 microM and site-site interactions were observed (n = 1.4). Magnesium ions were stimulatory (Kd = 1.5 mM) but zinc ions were powerful non-competitive inhibitors (Kd = 6.2 microM) of solubilized enzyme. Treatment of solubilized alkaline phosphatase with Chellex 100 reduced the original PNPPase activity to 5%. Cobalt (K0.5 = 10.1 microM), magnesium (K0.5 = 29.5 microM) and manganese ions (K0.5 = 5 microM) restored the activity of the apoenzyme with positive cooperativity, suggesting that phosphatidylinositol-specific phospholipase C-solubilized alkaline phosphatase is a metalloenzyme. The stimulation of the apoenzyme by calcium ions (K0.5 = 653 microM) was lower than that observed for the other ions (26%) and exhibited site-site interactions (n = 0.7). Zinc ions had no effect on the apoenzyme of the solubilized enzyme.
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PMID:Osseous plate alkaline phosphatase is anchored by GPI. 808 Dec 65

The ultracytochemical investigation of the localization of Mg(2+)-ATPase, Na+, K(+)-ATPase (ouabain-sensitive potassium-dependent p-nitrophenylphosphatase component of Na+, K(+)-ATPase complex), Ca(2+)-ATPase and alkaline phosphatase activities in choroid plexus of the adult and old rat brain ventricles has shown the age-related decrease in intensity of the enzymatic reactions. This can influence the character of liquor production, as well as metabolic, regulatory and transport processes in the blood-liquor barrier in aging. The most typical areas of enzymes activity localization have been established, which are zones of the greatest functional significance.
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PMID:[Ultracytochemical research on the different ATPases and alkaline phosphatase of the vascular plexuses of the rat brain in aging]. 821 24

Alkaline phosphatase activity was released up to 100% from the membrane by incubating the rat osseous plate membrane-bound enzyme with phosphatidylinositol-specific phospholipase C. The molecular weight of the released enzyme was 145,000 on Sephacryl S-300 gel filtration and 66,000 on PAGE-SDS, suggesting a dimeric structure. Solubilization of the membrane-bound enzyme with phospholipase C did not destroy its ability to hydrolyse PNPP, ATP and pyrophosphate. The hydrolysis of ATP and PNPP by phosphatidylinositol-specific phospholipase C-released enzyme exhibited 'Michaelian' kinetics with K0.5 = 70 and 979 microM, respectively. For pyrophosphate, K0.5 was 128 microM and site-site interactions were observed (n = 1.4). Magnesium ions were stimulatory (K0.5 = 1.5 mM) and zinc ions were a powerful noncompetitive inhibitor (Ki = 6.2 microM) of phosphatidylinositol-specific phospholipase C-released enzyme. Phosphatidylinositol-specific phospholipase C-released alkaline phosphatase was relatively stable at 40 degrees C. However, with increasing temperature from 40-60 degrees C, the enzyme was inactivated rapidly following first order kinetics and thermal inactivation constants varied from 5.08 x 10(-4) min-1 to 0.684 min-1. Treatment of phosphatydilinositol-specific phospholipase C-released alkaline phosphatase with Chellex 100 depleted to 5% its original PNPPase activity. Magnesium (K0.5 = 29.5 microM), manganese (K0.5 = 5 microM) and cobalt ions (K0.5 = 10.1 microM) restored the activity of Chelex-treated enzyme, demonstrating its metalloenzyme nature. The stimulation of Chelex-treated enzyme by calcium ions (K0.5 = 653 microM) was less effective (only 26%) and occurred with site-site interactions (n = 0.7). Zinc ions had no stimulatory effects. The possibility that the soluble form of the enzyme, detected during endochondral ossification, would arise by the hydrolysis of the Pl-anchored form of osseous plate alkaline phosphatase is discussed.
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PMID:Characterization of the phosphatidylinositol-specific phospholipase C-released form of rat osseous plate alkaline phosphatase and its possible significance on endochondral ossification. 875 Nov 58

A polynucleotide (or a fragment of RNA) was purified to apparent homogeneity by HPLC from mycelium of the wild strain 74A of the mould Neurospora crassa, after growth on sucrose and in the presence of saturating amounts of inorganic phosphate (Pi) for 72 hr at 30 degrees. The M(r) was ca 20,000 as determined by HPLC at pH 6.8. Polynucleotide synthesis ranged from 4.0 to 6.5 micrograms polynucleotide per mg dry mycelium in mycelium of the wild strain 74A and the various phosphorus regulatory and structural mutant strains of the mould N. crassa. Kinetic data showed that the polynucleotide interacts with mycelial Pi-repressible alkaline phosphatase by inhibiting its p-nitrophenylphosphatase activity and by protecting the enzyme against thermal inactivation in the presence of high concentrations of ammonium sulphate.
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PMID:Properties of a polynucleotide synthesized by strain 74A of Neurospora crassa. 882 30

The biological cycle of most amphibians undergoes seasonal variations. In this study, we investigated the mesonephros of Rana esculenta during active life and the natural hibernation period. The ultrastructural morphology of the different tracts constituting the nephron was analysed. Moreover, to evaluate the effect of seasonal temperature variations on the mesonephros function, the activity of some enzymes linked to membrane transport and playing regulatory roles in various metabolic pathways was investigated in different tracts of the frog nephron. During hibernation the glomerular filtration barrier appeared thicker than in the active life, lysosomes and paraplasmatic material, mostly glycogen, being accumulated in the proximal and distal tubule cells respectively. Cytoplasmic organelles, i.e., mitochondria, endoplasmic reticulum were observed in segregated areas. At the same time, changes in some enzyme activities were noted. The activity of some membrane-transport enzymes (5' nucleotidase and K+-p-nitrophenyl phosphatase) and of energetic metabolism (succinic dehydrogenase) was reduced. Nevertheless the alkaline phosphatase activity was not changed significantly, and this suggests that some metabolic activities were preserved in the hibernating samples. These results indicate morpho-functional adaptations of the kidney cells that preserve their role in osmoregulation and some metabolic processes, even during unfavourable seasons.
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PMID:An ultrastructural and cytochemical study of the mesonephros of Rana esculenta during activity and hibernation. 909 Sep 90

A soluble form of an alkaline phosphatase, obtained from the osseous plate of streptozotocin-induced diabetic rats, was purified 90-fold with a yield of 26%. The calculated Mr of the purified enzyme was 80,000 by denaturing polyacrylamide gel electrophoresis and 160,000 by gel filtration on Sephacryl S-300, suggesting a dimeric structure for its native form. In the absence of metal ions, the p-nitrophenylphosphatase activity of the purified enzyme was 4223.1 U/mg. Magnesium or calcium ion concentrations up to 2 mM increased the specific activity of the enzyme to 9896.5 and 10,796.2 U/mg, respectively. The enzyme was stimulated to a lesser extent by MnCl2 (5390.1 U/mg) and CoCl2 (5088.2 U/mg). The purified soluble alkaline phosphatase showed a broad substrate specificity, and among the less hydrolyzed substrates were pyrophosphate (1517.6 U/mg) and bis-p-nitrophenylphosphate (499.6 U/mg). The enzyme was relatively stable at 45 degrees for periods as long as 180 min, but was denatured rapidly above 50 degrees, following first order kinetics with T1/2 values ranging from 3.5 to 57.7 min. The results reported herein suggested that the soluble form of alkaline phosphatase from streptozotocin-induced diabetic rats had its kinetic properties altered, apparently as a consequence of changes in metal-binding properties.
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PMID:Streptozotocin-induced diabetes: significant changes in the kinetic properties of the soluble form of rat bone alkaline phosphatase. 1044 95

In an attempt to understand the mechanism underlying the tissue-dependent function, the expression of NHE-1 protein and its sub cellular localization was examined in the rat GI-tract and other tissues. Rat NHE-1 polyclonal antibodies were raised in rabbits using a NHE-1 fusion protein antigen. The antibodies recognized a 110 kD protein in rats and mice, but not in human or rabbit RBCs. Colon, stomach, brain, spleen and kidney expressed NHE-1 protein abundantly, whereas the skeletal muscle the least abundant. Ouabain-sensitive-K+-stimulated p-nitrophenylphosphatase (PNPPase), the partial activity of the sodium pump and alkaline phosphatase (Apase) were used as the markers of the basolateral and apical membranes. NHE-1 was detected predominantly in the PNPPase enriched membrane fractions, but was also detected in the apical membrane enriched fractions in the kidney cortex, jejunum and colon at a lower level. NHE-1 was detected in the plasma membrane enriched fractions from the skeletal muscle and ventricle. Immunofluorescence data showed a similar localization pattern of NHE-1 in the colon and kidney sections. These findings suggest that NHE-1 is localized both on the apical and basolateral membrane. In view of its similar sub cellular localization in the GI-tract and kidney, but a different level of expression, might suggest that the level of protein, but not the sub cellular distribution is important to regulate its tissue-dependent function.
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PMID:Expression and sub cellular localization of the sodium hydrogen exchanger isoform-1 in rat tissues: a possible functional relevance. 1135 47


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