PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “ALKALINE PHOSPHATASE”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 469 records · Page 26Linked to original sources
PubMed1987

Specific assays for human alkaline phosphatase isozymes.

Specific assays for human intestinal and liver alkaline phosphatases were developed by use of isozyme specific monoclonal antibodies bound to paper discs. The assays are fast, specific and convenient to use as demonstrated by determinations of alkaline phosphatase isozymes in sera and tissues. In sera from forty healthy individuals the activity of the tissue unspecific alkaline phosphatase was determined to 32 +/- 12 IU/l (mean +/- SD). The activity of the intestinal alkaline phosphatase was found to be ten-fold lower, 3.5 +/- 6.3 IU/l (mean +/- SD), and of the placental alkaline phosphatase another ten-fold lower, 0.3 +/- 0.2 IU/l (mean +/- SD), than that of the tissue unspecific alkaline phosphatase. Several normal tissues contained all three isozymes, the intestinal mucosa, for example, which besides intestinal alkaline phosphatase also expresses trace amounts of placental and liver-bone-kidney alkaline phosphatase. Seminomas, known to express eutopically placental-like alkaline phosphatase were demonstrated to contain increased levels of both intestinal and liver-bone-kidney alkaline phosphatases as compared to the normal testis.

Alkaline Phosphatase↗
PubMed1995

Protein phosphatase inhibitors, okadaic acid and calyculin A, induce alkaline phosphatase activity in osteoblastic cells derived from newborn mouse calvaria.

To determine whether protein phosphatases can affect bone regulation, we examined the effects of okadaic acid (OA) and calyculin A (CA), specific inhibitors of protein phosphatases type 1 and type 2A, on alkaline phosphatase activity of mouse osteoblastic cells. Clone MC3T3-E1 cells were cultured with varying concentrations of OA and CA. OA and CA stimulated alkaline phosphatase (ALP) activity in the cells in dose-dependent fashion with a maximal effect at concentrations of 5 nM and 2 nM, respectively. The properties of OA-induced and native ALP in the cells were the same and they were liver-bone-kidney type. These results show that protein phosphatase inhibitors stimulate bone formation in vitro and that phosphorylation and dephosphorylation of specific proteins in the cells may be involved in bone regulation in vivo as well.

Alkaline Phosphatase↗
PubMed1986

Biochemical characterization of alkaline phosphatase from partly mineralized bovine enamel.

Alkaline phosphatase (AP) from partly mineralized bovine enamel was studied. The enzyme resembles alkaline phosphatases in other calcifying tissues. The Km was 0.46 mM; the phosphatase was strongly inhibited by 1 mM Levamisol or EDTA and it showed the same sensitivity towards heating as bone alkaline phosphatase. The inactivation caused by phosphate ions was approximately about 30%. In a zymogram, five isozymes of enamel alkaline phosphatase can be recognized. In a SDS-polyacrylamide gel a single band showing enzyme activity was visualized. This enzyme has an apparent molecular weight of 140,000.

Alkaline Phosphatase↗
PubMed1981

Altered form of placental alkaline phosphatase produced by JAR choriocarcinoma cells in culture.

The alkaline phosphatase activity expressed by JAR choriocarcinoma cells was compared to the placental isoenzyme of human alkaline phosphatase by several criteria. JAR cell alkaline phosphatase was similar to the placental isoenzyme with respect to heat and urea stability and sensitivity to most inhibitors, but it differed significantly from placental alkaline phosphatase in its sensitivity to L-phenylalanylglycylglycine. In contrast to the serum form of placental alkaline phosphatase, the JAR cell enzyme was highly hydrophobic as determined by octyl agarose chromatography and appeared to be larger than the placental isoenzyme based on gel filtration and polyacrylamide gel electrophoresis. The slowly migrating hydrophobic JAR cell activity could be converted into a fast-migrating hydrophilic form similar to the serum placental isoenzyme by treatment with trypsin-like proteases. Conversion to the hydrophilic form was accompanied by a decrease in subunit molecular weight from 68,000 to 66,000, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of 33P-labeled enzyme. Peptide mapping of the 33P-labeled molecules by limited proteolysis in the presence of sodium dodecyl sulfate showed JAR cell alkaline phosphatase to be closely related to the placental isoenzyme with respect to primary structure. However, placental alkaline phosphatase appeared to be richer in sialic acid residues than was the JAR cell enzyme. We conclude that JAR cells produce a form of placental alkaline phosphatase that contains a hydrophobic region not associated with the free serum enzyme and that the tumor cell enzyme is modified or processed differently than is the enzyme found in the term placenta.

Alkaline Phosphatase↗
PubMed1991

Isolation, transcription, and inactivation of the gene for an atypical alkaline phosphatase of Synechococcus sp. strain PCC 7942.

The alkaline phosphatase of Synechococcus sp. strain PCC 7942 is 145 kDa, which is larger than any alkaline phosphatase previously characterized and approximately three times the size of the analogous enzyme in Escherichia coli. The gene for the alkaline phosphatase, phoA, was cloned and sequenced, and the protein that it encodes was found to have little similarity to other phosphatases. Some sequence similarities were observed between the Synechococcus sp. strain PCC 7942 alkaline phosphatase, the alpha subunit of the ATPase from bacteria and chloroplasts, and the UshA sugar hydrolase of E. coli. Also, limited sequence similarity was observed between a region of the phosphatase and a motif implicated in nucleotide binding. Interestingly, although the alkaline phosphatase is transported across the inner cytoplasmic membrane and into the periplasmic space, it does not appear to have a cleavable signal sequence at its amino terminus. The half-life of the mRNA encoding the alkaline phosphatase, measured after inhibition of RNA synthesis, is approximately 5 min. Similar kinetics for the loss of alkaline phosphatase mRNA occur upon the addition of phosphate to phosphate-depleted cultures, suggesting that high levels of this nutrient inhibit transcription from phoA almost immediately. The phoA gene also appears to be the first gene of an operon; the largest detectable transcript that hybridizes to a phoA gene-specific probe is 11 kb, over twice the size needed to encode the mature protein. Other phosphate-regulated mRNAs are also transcribed upstream of the phoA gene. Insertional inactivation of phoA results in the loss of extracellular, phosphate-regulated phosphatase activity but does not alter the capacity of the cell for phosphate uptake.

Alkaline Phosphatase↗
PubMed1971

Serum alkaline phosphatase in hypophosphatasia.

It is recognized that serum alkaline phosphatase may reflect enzyme contributions from bone, liver, and intestine. We have investigated serum alkaline phosphatases in two siblings with hypophosphatasia. After administration of long-chain triglycerides, the major alkaline phosphatase component of their sera was shown to be of intestinal origin on the basis of inhibition by l-phenylalanine. Starch block electrophoresis suggested that there were other regions of l-phenylalanine-sensitive alkaline phosphatase in addition to the major slow-moving intestinal band. Medium-chain triglycerides which are absorbed by the portal route did not cause a similar augmentation of intestinal alkaline phosphatase activity. These studies indicate that serum levels of intestinal alkaline phosphatase are increased normally after long-chain fat feeding in hypophosphatasia and may be the major component of total serum alkaline phosphatase activity.

Alkaline Phosphatase↗
PubMed1981

Independent biosynthesis of soluble and membrane-bound alkaline phosphatases in the suckling rat ileum.

Enzymically active intestinal alkaline phosphatase exists in both soluble and membrane-bound forms in the suckling rat. Antiserum prepared against purified soluble alkaline phosphatase (anti-AlP) was shown to be monospecific when assessed by Ouchterlony double-diffusion analysis and immunoelectrophoresis. The two forms of alkaline phosphatase were antigenically identical and possessed similar affinities for anti-AlP. To study the biosynthesis of the two forms, 14-day-old rats were injected intraperitoneally with [(3)H]leucine. The labelling kinetics of alkaline phosphatase, extracted from supernatant and brush-border membrane fractions with anti-AlP, was followed over 20h. Incorporation of [(3)H]leucine into membrane-bound alkaline phosphatase was rapid, reaching a plateau at 6h. The soluble enzyme showed slower incorporation of label and maximal radioactivity was not reached until 12h after labelling, a lag of 6h behind the membrane-bound enzyme. Soluble alkaline phosphatase could not have been a precursor of the membrane form, as there was no early peak of radioactivity in the soluble form. To determine if the soluble enzyme was irreversibly derived from the membrane enzyme, a newly developed technique of labelling brush-border membrane proteins in vivo by intraluminal injection of diazotized [(125)I]iodosulphanilic acid was used. The appearance of (125)I in soluble and membrane alkaline phosphatase was then monitored over a 7h period, encompassing the lag between maximal leucine labelling of the two forms. The results failed to show either a proportional transfer of radioactivity from membrane to soluble alkaline phosphatase or an absolute increase in radioactivity of the soluble form during degradation of brush-border alkaline phosphatase. Therefore there does not appear to be a serial precursor/product relationship between the soluble and membrane-bound forms of suckling-rat intestinal alkaline phosphatase.

Alkaline Phosphatase↗
PubMed1980

Role of phosphatidylinositol in attachment of alkaline phosphatase to membranes.

The mechanism of release of alkaline phosphatase from membranes by phosphatidylinositol-specific phospholipase C from Staphylococcus aureus was studied. Alkaline phosphatase was readily released from pig kidney microsomes by phospholipase C but not by a variety of other treatments, e.g., high ionic strength, extremes of pH, divalent cations, chelating agents, or analogues of the polar head group of phosphatidylinositol. Alkaline phosphatase released from microsomes by phospholipase C did not bind to phospholipid vesicles containing phosphatidylinositol. Alkaline phosphatase solubilized from microsomes by butanol extraction, however, was able to bind phospholipid vesicles even when they contained no phosphatidylinositol. The ability of butanol-extracted alkaline phosphatase to bind to phospholipid vesicles was destroyed by added phosphatidylinositol-specific phospholipase C. Hydrolysis of added phosphatidylinositol by endogenous phospholipase activity in butanol extracts was also accompanied by loss of binding ability. Loss of binding ability was paralleled by a decrease in the apparent molecular weight of alkaline phosphatase. These results indicate that alkaline phosphatase is attached to membranes by a strong interaction with phosphatidylinositol.

Alkaline Phosphatase↗
PubMed1981

Alkaline phosphatase and calcification, correlated or not?

The effects of alkaline phosphatase inhibitors (levamisole, L-bromotetramisole) on the activity of the enzyme and on calcification in vitro were studied, to find out whether there is a relationship between alkaline phosphatase and calcification. Metatarsal bones of 15 1/4-day-old embryonic mice were dissected and cultured for 40 hours in the presence and absence of inhibitor. Levamisole and L-bromotetramisole fully inhibited calcification in vitro when present in concentrations which almost totally inhibited alkaline phosphatase activity, as measured biochemically or histochemically. However, incorporation of 3H-thymidine and 35S-sulphate was also inhibited. Furthermore, D-bromotetramisole, the dextroform of bromotetramisole which has no effect on alkaline phosphatase, inhibited calcification and 3H-thymidine and 35S-sulphate incorporation as well. The results of this study show that these inhibitors cannot be used to study the relationship between alkaline phosphatase and calcification. In addition, they suggest that although alkaline phosphatase may be important for the process of calcification, it is probably not a critical factor.

Alkaline Phosphatase↗
PubMed1976

Plasma membrane localization of alkaline phosphatase in HeLa cells.

The localization of alkaline phosphatase in HeLa cells was examined by electron microscopic histochemistry and subcellular fractionation techniques. Two monophenotypic sublines of HeLa cells which respectively produced Regan and non-Regan isoenzymes of alkaline phosphatase were used for this study. The electron microscopic histochemical results showed that in both sublines the major location of alkaline phosphatase is in the plasma membrane. The enzyme reaction was occasionally observed in some of the dense body lysosomes. This result was supported by data obtained from a subcellular fractionation study which showed that the microsomal fraction rich in plasma membrane fragments had the highest activity of alkaline phosphatase. The distribution of this enzyme among the subcellular fractions closely paralleled that of the 5'-nucleotidase, a plasma membrane marker enzyme. Characterization of the alkaline phosphatase present in each subcellular fraction showed identical enzyme properties, which suggests that a single isoenzyme exists among fractions obtained from each cell line. The results, therefore, confirm the reports suggesting that plasma membrane is the major site of alkaline phosphatase localization in HeLa cells. The absence of any enzyme reaction in the perimitochondrial space in these cultured tumor cells also indicates that the mitochondrial localization of the Regan isoenzyme reported in ovarian cancer may not be a common phenomenon in Regan-producing cancer cells.

Alkaline Phosphatase↗
PubMed1981

[Alkaline phosphatase isoenzymes and hyperthyroidism].

We determined the serum total alkaline phosphatase as well as the alkaline phosphatase isoenzyme pattern in untreated and treated hyperthyreoses in the condition of euthyreosis and compared them with those of a healthy control group. The isoenzyme patterns, expressed as L/K quotient, ranged between 1.3 and 2.5 in the normal group and between 0.3 and 1.3 in the group with hyperthyreosis. The increase of the total alkaline phosphatase in hyperthyreosis was nearly exclusively conditioned by the increase of the activity of the osseous isoenzyme. The latter was increased already also then, when the total alkaline phosphatase had not transgressed the upper border of the normal. Depending on the functional condition of the thyroid gland the liver isoenzyme did not show any significant changes. In the course up to one year under thyrostatic therapy the increased activity of the osseous alkaline phosphatase decreased into the normal region as an expression of the very slowly repairing hyperthyreosis-conditioned disturbances of the osseous metabolism. An increase of the activity of the total alkaline phosphatase or of the osseous isoenzyme in the initial phase of a thyreostatic therapy of the sequel of an increase of the reactive activity of osteoblasts and must not lead to diagnostic and therapeutic uncertainties. By reason of the high sensitivity of the L/K quotient in hyperthyreoses (L/K at 95.5 % below 1.3) with a simultaneously high specifity of 89.5% the alkaline osseous phosphatase is to be discussed by all means as a helpful parameter of the peripheral function of the thyroid gland.

Alkaline Phosphatase↗
PubMed1985

On the difference between colonic and small intestinal alkaline phosphatase.

Colonic and small intestinal alkaline phosphatase extracts were studied biochemically and electrophoretically to elucidate the source of a reported difference in cellulose acetate electrophoretic mobility. Both preparations were inactivated with 0.5 mmol/L L-phenylalanine but retained full activity in the presence of 1.0 mmol/L tetramisole. Treatment with neuraminidase changed a minor fraction of the small intestinal but the major portion of the colonic alkaline phosphatase to a cathodically migrating form. The most likely explanation for our findings is that the colon and small intestinal alkaline phosphatase are mixtures of the same multiple forms but in different proportions.

Alkaline Phosphatase↗
PubMed1985

The active-site and amino-terminal amino acid sequence of bovine intestinal alkaline phosphatase.

The active site of bovine intestinal alkaline phosphatase (orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1) was labeled with [32P]Pi, a radioactive CNBr peptide was isolated and the amino acid sequence was determined. The sequence of the active-site peptide has limited homology (26%) with the active-site sequence of Escherichia coli alkaline phosphatase except for the ten residues immediately flanking the active-site serine (70%). A possible amino acid sequence deduced from the amino acid composition of an active-site tryptic peptide from human placental alkaline phosphatase is very similar to the bovine intestinal active-site sequence. The amino-terminal sequence of bovine intestinal alkaline phosphatase is homologous (69%) with the human placental enzyme but not with the E. coli phosphatase.

Alkaline Phosphatase↗
PubMed1976

The effect of 1alpha-hydroxyvitamin D3 and cortisone on the development of chick duodenal alkaline phosphatase in organ culture.

The development of alkaline phosphatase influenced by 1 alpha-OH-D3 (a synthetic active form of vitamin D3) and cortisone was studied in chick duodenal organ cultures. The administration of cortisone to the embryo in ovo on the 14th day of incubation resulted in a precocious increase in alkaline phosphatase after six days (20-day embryo). When duodena from 14-, 18- and 20-day embryos were cultured in the presence of cortisone, there was no significant enhancement of alkaline phosphatase activity except for a marginal effect observed in the 18-day duodenum. On the other hand, the alkaline phosphatase activity in cultured duodena from 20-day chick embryos was significantly stimulated by the addition of 1 alpha-OH-D3. The effects of cortisone and 1 alpha-OHD-3 were not additive. The activity of maltase, another intestinal enzyme, was not influenced by 1 alpha-OH-D3. Studies on inactivation of alkaline phosphatase by EDTA suggest that the observed increase in alkaline phosphatase activity induced by the administration of 1 alpha-OH-D in vitro may be related to the qualitative changes in the enzyme that take place during development in vivo.

Alkaline Phosphatase↗