Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.3.1 (alkaline phosphatase)
 47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In rats changes in plasma membrane enzyme activities due to Gal-N intoxication were studied by enzymehistochemical methods. The bile canalicular 5'-nucleotidase and nucleoside polyphosphatase activities decreased; the sinusoidal 5'-nucleotidase remained unchanged. The bile canalicular leucyl-beta-naphthyl-amidase showed an increase in activity; the alkaline phosphatase activity remained unchanged. In contrast to the spotty necrosis, changes in plasma membrane enzyme activities were seen in all liver cells, suggesting that changes of these activities, occurring after Gal-N treatment, do not correlate with cell death. The conclusion was drawn that the deviations of the enzyme activities might be due to changes in the lipid environment of the enzyme proteins in the membrane. With the exception of alkaline phosphatase, partial hepatectomy caused the same changes in enzyme activities as did Gal-N intoxication. Nevertheless Gal-N administration to partial hepatectomized rats did not lead to hepatic necrosis. Galactose given simultaneously or within two hours after Gal-N prevented both changes in plasma membrane enzyme activities and hepatocellular damage. This suggests an important role of galactolipids and galactoproteins in the plasma membrane alterations.
 ...
PMID:A histochemical study about changes in rat liver plasma membrane enzyme activities after galactosamine administration. 15 4

Solubilization of protein membranes by detergents and protein liberation from the membranes induced by proteolytic enzymes results in a change of activity of membrane-bound phosphohydrolases--alkaline phosphatase and polyphosphatase. The activity of enzymes under conditions of repressed and derepressed biosynthesis of phosphohydrolases changes differently, thus indicating their different membrane environment in the two types of membranes. Some data were obtained on the localization of alkaline phosphatase in a hydrophobic region, possibly in lipid bilayer and polyphosphatase in the surface layers of the membrane.
 ...
PMID:[Effect of detergents and proteolytic enzymes on membrane-bound phosphohydrolases in Escherichia coli cells with repressed and depressed biosynthesis of these enzymes]. 18 55

The effects of orthophosphate and mutations in the regulatory genes of alkaline phosphatase on the activities of pyrophosphatase and polyphosphatase of E. coli were studied. It was shown that orthophosphate represses the synthesis of alkaline phosphatase as well as that of polyphosphatase without having any effect on pyrophosphatase. The genes phoR and phoS are involved in the formation of a repressory complex both for alkaline phosphatase and polyphosphatase. The gene phoT is probably involved in a partial repression of pyrophosphatase synthesis.
 ...
PMID:[Interrelationship between metabolic and genetic regulation of alkaline phosphatase and poly- and pyrophosphatases]. 21 15

The phosphorus contents of acid-soluble pools, lipid, ribonucleic acid, and acid-insoluble polyphosphate were lowered in Synechococcus in proportion to the reduction in growth rate in phosphate-limited but not in nitrate-limited continuous culture. Phosphorus in these cell fractions was lost proportionately during progressive phosphate starvation of batch cultures. Acid-insoluble polyphosphate was always present in all cultural conditions to about 10% of total cell phosphorus and did not turn over during balanced exponential growth. Extensive polyphosphate formation occurred transiently when phosphate was given to cells which had been phosphate limited. This material was broken down after 8 h even in the presence of excess external orthophosphate, and its phosphorus was transferred into other cell fractions, notably ribonucleic acid. Phosphate uptake kinetics indicated an invariant apparent K(m) of about 0.5 muM, but V(max) was 40 to 50 times greater in cells from phosphate-limited cultures than in cells from nitrate-limited or balanced batch cultures. Over 90% of the phosphate taken up within the first 30 s at 15 degrees C was recovered as orthophosphate. The uptake process is highly specific, since neither phosphate entry nor growth was affected by a 100-fold excess of arsenate. The activity of polyphosphate synthetase in cell extracts increased at least 20-fold during phosphate starvation or in phosphate-restricted growth, but polyphosphatase activity was little changed by different growth conditions. The findings suggest that derepression of the phosphate transport and polyphosphate-synthesizing systems as well as alkaline phosphatase occurs in phosphate shortage, but that the breakdown of polyphosphate in this organism is regulated by modulation of existing enzyme activity.
 ...
PMID:Regulation of phosphate accumulation in the unicellular cyanobacterium Synechococcus. 22 42

The activity of several phosphohydrolases, viz. alkaline phosphatase (EC 3.1.3.1), acid phosphatase (EC 3.1.3.2), ATPase (EC 3.6.1.3), tripolyphosphatase (EC 3.6.1.2) and polyphosphatase (EC 3.6.1.11), was studied in Pseudomonas aeruginosa VKM B-889 and Pseudomonas maltophilia VKM B-591. In the absence of orthophosphate in the medium when alkaline phosphatase was derepressed, its activity in P. aeruginosa rose in parallel with that of acid phosphatase, tripolyphosphatase and polyphosphatase. The maximal activity of alkaline phosphatase was detected in the cultural broth while that of the remaining enzymes was found in the soluble fraction of the cells. In P. maltophilia, the activity of phosphohydrolases was not regulated with orthophosphate; even when the cells were grown in its presence, the activity was much higher than that of acid phosphatase, ATPase and tripolyphosphatase of the derepressed cells of P. aeruginosa. In P. maltophilia, the maximal activity of the enzymes, just as that of alkaline phosphatase, was detected in the fraction of cellular membranes.
 ...
PMID:[Exogenous orthophosphate regulation of the phosphohydrolase activities of Pseudomonas aeruginosa and Pseudomonas maltophilia]. 627 4

Polyphosphate metabolism in Escherichia coli was studied in order to determine the role of polyphosphates in energy and phosphate metabolism. Phosphate-shift experiments were performed on wild-type E. coli W3110 and on an E. coli strain mutant in the genes encoding the polyphosphate-metabolizing enzymes polyphosphate kinase (PPK) and polyphosphatase (PPX). The levels of polyphosphates were measured by [31P]NMR, and the activities of PPK and PPX were measured using enzymatic assays. During phosphate starvation, the intracellular level of polyphosphate was not detectable in E. coli W3110; the activities of PPX and alkaline phosphatase were high relative to those during exponential growth. During the shift from phosphate starvation to phosphate surplus conditions, PPX activity decreased and PPK activity and intracellular polyphosphate stores increased dramatically. These results imply an important role for polyphosphates in cellular energy and phosphate storage and in adaptation to adverse growth conditions.
 ...
PMID:Polyphosphate metabolism in Escherichia coli. 783 34

The effects of some protein kinase effectors on phosphohydrolase and transport activities of yeast vacuoles have been studied. The platelet-activating factor (PAF), a plant vacuolar protein kinase C stimulator, had a protonophoric and membrane-damaging effects on yeast vacuoles and inhibited the ATP-dependent delta mu H+ formation and ATP-dependent secondary transport but stimulated the ATPase and pyrophosphatase hydrolase activities by abrogating proton control. PAF increasing the tonoplast permeability for the corresponding substrates also stimulated pyrophosphatase, polyphosphatase and alkaline phosphatase activities. Lysolipid sphingosine, a plant vacuolar protein kinase C inhibitor, poorly stimulated the ATPase activity and the ATP-dependent formation of Em in isolated yeast vacuoles, while the pyrophosphatase activity increased by 200%. Other hydrolase activities tested were insensitive to the effect of the lysolipid. Sphingosine inhibited the ATP-dependent citrate transport only insignificantly. Heparin, an effective casein kinase inhibitor, suppressed the ATPase and polyphosphatase activities in isolated yeast vacuoles. The polyphosphatase activity was inhibited both in the vacuolar sap and the tonoplast solubilized by a Zwittergent TM-314, in contrast with the ATPase activity which was inhibited by heparin only in isolated vacuoles. Heparin is suggested to inhibit polyphosphatase by directly influencing the enzyme.
 ...
PMID:[The effect of PAF, sphingosine and heparin on certain phosphohydrolase and transport activity of yeast vacuoles]. 794 17

Polyphosphate degradation and phosphate secretion were optimized in Escherichia coli strains overexpressing the E. coli polyphosphate kinase gene (ppk) and either the E. coli polyphosphatase gene (ppx) or the Saccharomyces cerevisiae polyphosphatase gene (scPPX1) from different inducible promoters on medium- and high-copy plasmids. The use of a host strain without functional ppk or ppx genes on the chromosome yielded the highest levels of polyphosphate, as well as the fastest degradation of polyphosphate when the gene for polyphosphatase was induced. The introduction of a hybrid metabolic pathway consisting of the E. coli ppk gene and the S. cerevisiae polyphosphatase gene resulted in lower polyphosphate concentrations than when using both the ppk and ppx genes from E. coli, and did not significantly improve the degradation rate. It was also found that the rate of polyphosphate degradation was highest when ppx was induced late in growth, most likely due to the high intracellular polyphosphate concentration. The phosphate released from polyphosphate allowed the growth of phosphate-starved cells; excess phosphate was secreted into the medium, leading to a down-regulation of the phosphate-starvation (Pho) response. The production of alkaline phosphatase, an indicator of the Pho response, can be precisely controlled by manipulating the degree of ppx induction. Copyright 1998 John Wiley & Sons, Inc.
 ...
PMID:Optimization of polyphosphate degradation and phosphate secretion using hybrid metabolic pathways and engineered host strains 1009 96

Harold, F. M. (National Jewish Hospital, Denver, Colo.), and Ruth L. Harold. Degradation of inorganic polyphosphate in mutants of Aerobacter aerogenes. J. Bacteriol. 89:1262-1270. 1965.-Extracts of Aerobacter aerogenes contained two enzymes capable of degrading polyphosphate, polyphosphatase and polyphosphate kinase. By use of a suicide technique, a mutant (Pn-4) blocked in polyphosphate degradation was isolated; this mutant was found to lack polyphosphatase. The results indicate that polyphosphatase mediates the main pathway of polyphosphate degradation, and, therefore, that polyphosphate does not serve as a microbial phosphagen. A second mutant (Pn-3) exhibited transient accumulation of polyphosphate when cells were transferred to fresh growth medium. This strain was constitutive for elevated levels of polyphosphate kinase, polyphosphatase, and alkaline phosphatase; the transient accumulation of polyphosphate may be due to the shifting ratios of the biosynthetic and degradative enzymes during growth. These mutants were employed in studies on the competitive relationship between polyphosphate and nucleic acids. It was concluded that nucleic acid synthesis inhibits polyphosphate synthesis and also stimulates polyphosphate degradation.
 ...
PMID:DEGRADATION OF INORGANIC POLYPHOSPHATE IN MUTANTS OF AEROBACTER AEROGENES. 1429 96

Relatively large amounts of inorganic polyphosphate [poly(P)] (400 microM) have been found in normal osteoblasts. The effect of poly(P) with an average chain length of 65 phosphate residues on cell calcification was therefore investigated with the use of MC3T3-E1 cells. Expression of both osteopontin and osteocalcin was induced by poly(P) (0.1 approximately 1 mM), and cells treated with poly(P) were strongly stained by alizarin red. In addition, the level of alkaline phosphatase activity induced in poly(P)-treated cells was two-fold higher than that in either orthophosphate-treated or control cells but not higher than that in cells treated with beta-glycerophosphate and ascorbic acid. In contrast, however, polyphosphatase activities were activated by poly(P) treatment to levels up to six-fold greater than that in controls. MC3T3-E1 cells may utilize poly(P) as a phosphate source for calcification rather than phosphate sources that are mainly produced by ALPase. Poly(P)-dependent induction of polyphosphatase activities may therefore promote calcification in MC3T3-E1 cells.
 ...
PMID:Induction of calcification in MC3T3-E1 cells by inorganic polyphosphate. 1527 69


1 2 Next >>