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PubMed1988

Purification and some of the properties of alkaline phosphatase in guinea fowls (Numida meleagris galeata).

1. Alkaline phosphatase activity in the plasma of different strains of guinea fowls showed considerable variation both within and between sexes as well as within and between strains. 2. The enzymes from different strains of wild guinea fowls had different mobilities on disc polyacrylamide electrophoresis but each was characterised by a single band. 3. When the enzyme was purified 163-fold from the plasma of a domesticated grey breasted strain, both ion-exchange chromatography and gel-filtration purification steps yielded a single band of enzyme. 4. The purified enzyme had a molecular weight of 79,400 +/- 3,000 and was stable up to 60 degrees C at the optimum pH of 9.6. 5. Evidence is provided that guinea fowl alkaline phosphatase is a metalloenzyme.

Alkaline Phosphatase↗
PubMed2006

Effect of aluminum phosphate on alkaline phosphatase activity of polyurethane foam immobilized cyanobacteria.

The impact of insoluble phosphorus such as aluminum and rock phosphate on alkaline phosphatase activity of polyurethane foam immobilized cyanobacteria was assessed. Polyurethane foam immobilized Nodularia recorded the highest alkaline phosphatase activity of 9.04 (m. mol p-nitrophenol released h(-1) mg(-1) protein) in vitro. A higher concentration of aluminum phosphate was recorded a 25% reduction in alkaline phosphatase activity, ammonia content, and available phosphorus in culture filtrate of polyurethane foam immobilized cyanobacteria. In general, immobilized cyanobacteria exhibited a higher alkaline phosphatase activity in rock phosphate than aluminum phosphate.

Alkaline Phosphatase↗
PubMed1989

Changes of activities of some transferases, alkaline phosphatase and cholinesterase in the blood of women using oral contraceptives and in vitro influence of these agents on tissular enzyme levels in rat liver.

Aspartate aminotransferase, alanine aminotransferase, gamma-glutamyltransferase, and alkaline phosphatase activities in the blood serum of women taking the oral contraceptive preparation Microgynon through extended periods were raised; the activity of cholinesterase was simultaneously reduced. In rats liver homogenates ethynylestradiol, one of the active components of Microgynon, acted as an inducer of gamma-glutamyltransferase and alkaline phosphatase while leaving aspartate aminotransferase and alanine aminotransferase unaffected, but reduced the level of cholinesterase. Norgestrel, the other active component of the preparation, suppressed the biosynthesis of gamma-glutamyltransferase and alkaline phosphatase while leaving aspartate aminotransferase, alanine aminotransferase and cholinesterase levels unaffected. A mixture of ethynylestradiol plus norgestrel in the mass proportion occurring in Microgynon produced the same effects upon gamma-glutamyltransferase and alkaline phosphatase as ethynylestradiol alone. Estradiol, the parent hormone of ethynylestradiol, lacked the inducing capability of the latter while ethynylpropargyl chloride induced gamma-glutamyltransferase and alkaline phosphatase so it was concluded the inducing effect of ethynylestradiol must be ascribed to the ethynyl radical. Progesterone, the parent of norgestrel, shared the latter's suppressive activity for gamma-glutamyltransferase and alkaline phosphatase biosynthesis, and behaved like its derivative towards the other enzymes.

Adult↗
PubMed1987

Immunohistochemical study of alkaline phosphatase in growth plate cartilage, bone, and fetal calf isolated chondrocytes using monoclonal antibodies.

Monoclonal antibodies prepared against alkaline phosphatase of matrix vesicles from fetal bovine growth plate cartilage were used to study the distribution of alkaline phosphatase in bovine bone and cartilage. Primary chondrocyte cultures from bovine growth plate cartilage were prepared and expression of this antigen was followed during 3 d long cultured period. Same monoclonal anti-alkaline phosphatase antibodies recognized both osteoblasts in metaphyseal bone as well as proliferating and hypertrophic chondrocytes in growth plate cartilage. Extracellular reaction was observed in lower areas of growth plate cartilage after hyaluronidase digestion of tissue sections. In isolated growth plate chondrocytes strong membrane associated reaction as well as weaker intracytoplasmic reaction were noticed and especially in large hypertrophic cells membrane reaction was clustered showing "capping-like" phenomenon. These results indicates the high similarity of alkaline phosphatase in bone and cartilage and its uneven distribution in chondrocyte plasma membrane.

Alkaline Phosphatase↗
PubMed1984

Alkaline phosphatase and gamma-glutamyl transpeptidase as polarization markers during the organization of LLC-PK1 cells into an epithelial membrane.

Confluent monolayers of LLC-PK1 cells, an epithelial cell derived from a normal pig kidney, contain high levels of alkaline phosphatase and gamma-glutamyl transpeptidase activities. Inhibition studies show a close similarity between alkaline phosphatase and the so-called liver-bone-kidney isoenzyme. Nearly complete recovery of both activities in the microsomal fraction demonstrates the membrane-bound characteristics of these enzymes. Histochemical localization of the enzymes activities on the apical membrane of LLC-PK1 cells confirms this observation. The activity of both enzymes decreases to very low levels when the cells are in exponential growth. Confluent monolayers of LLC-PK1 cells plated at saturation density with cells that were in active growth show a progressive increase in the activity of alkaline phosphatase and gamma-glutamyl transpeptidase. This increase is dependent on the synthesis de novo of RNA and protein and supports the conclusion that the activity of both enzymes is regulated at the transcriptional level. The development of these enzymes is delayed with respect to the development of the occluding junctions. This delay and the direct appearance of alkaline phosphatase activity in the apical membrane indicate that the different components of this membrane are inserted after the limits of the membrane have been established by the synthesis and assembly of the occluding junctions. Alkaline phosphatase activity of confluent monolayers can be further induced by reducing the concentration of phosphate in the medium. When the junctions are dissociated by incubating the monolayers in Ca2+-free medium, the alkaline phosphatase activity migrates freely beyond the limits of the apical membrane until it covers the entire cell surface. Both enzymes are synthesized even in the absence of contact between the cells, suggesting that the occluding junctions in LLC-PK1 monolayers are involved in the polarized distribution, but not in the modulation, of the synthesis of these enzymes. In addition, the progressive decrease in enzyme synthesis that is obtained by reducing the cell-substratum adhesion supports the idea that it is the cell-to-substrate and not the cell-to-cell interaction which is involved in the modulation of these enzymatic markers of the apical membrane.

Alkaline Phosphatase↗
PubMedDate not supplied

Alkaline phosphatase and ATPases in brush-border membranes of rat jejunum: distinct effects of divalent cations and of some inhibitors.

The effects of divalent cations and of some inhibitors on the activities of alkaline phosphatase and ATPase were examined in rat jejunal brush-border membranes (BBM) isolated by tha Ca(2+)-(BBMCa) or the Mg(2+)-precipitation method (BBMMg). Similar results were found in BBMCa and BBMMg though generally higher in BBMCa. Alkaline phosphatase activity was stimulated by 5 mM MgCl2 (30% to 44%), but not by 5 mM CaCl2 or 0.1 mM ZnCl2, at pH 9.5 or 7.4. ATPase activity was equally stimulated by 5 mM MgCl2 and by 5 mM CaCI2 (about 150%). Alkaline phosphatase activity was significantly inhibited by 1 mM vanadate, 5 mM diamox, 5.0 mM L-leucine and 1 mM theophylline. In contrast, Ca(2+)-ATPase and Mg(2+)-ATPase activities were not depressed by those alkaline phosphatase inhibitors, but were inhibited by 0.1 mM trifluoperazine (more than 70%). 0.1 mM ZnCl2 also appeared to be inhibitory to Ca(2+)-ATPase and Mg(2+)-ATPase, but not to alkaline phosphatase activity even in the presence of Ca2+ and Mg2+. These results suggest that Ca(2+)-ATPase and Mg(2+)-ATPase activities of the rat jejunal BBM are not merely manifestations of alkaline phosphatase, but rather belong to (a) distinct enzyme(s).

Acetazolamide↗
PubMed1984

An immunohistological study of testicular germ cell tumours using two different monoclonal antibodies against placental alkaline phosphatase.

Using two monoclonal antibodies directed against placental alkaline phosphatase (H17E2 and D20L) the immunohistological staining of testicular germ cell tumours was compared with that of a wide range of normal and malignant tissues. All seminomas and malignant teratomas tested gave strong positive labelling with H17E2 but were either negative or only patchily positive with D20L. Neither antibody gave any positive reaction on the normal tissues tested. All other malignancies were negative with both antibodies apart from two cases of ovarian and one case of endometrical cancer (strongly stained by H17E2) and three cases of colonic carcinoma (weakly and patchily stained by both H17E2 and D20L). This indicates that germ cell neoplasms generally express a form of placental alkaline phosphatase recognised by antibody H17E2.

Alkaline Phosphatase↗
PubMedDate not supplied

Enzyme polymorphisms, smoking, and human reproduction. A study of human placental alkaline phosphatase.

We investigated the possible effects of placental alkaline phosphatase (PLAP) genotype on the deleterious action of maternal smoke on intrauterine survival and birthweight. PLAP is a highly polymorphic enzyme with several alleles associated with different enzymatic activities. PLAP is produced by the embryo and is found in maternal blood, where it is responsible for the rise of serum alkaline phosphatase during pregnancy. Two hundred and fourteen Caucasian consecutive newborn infants delivered in the Maternity Department of the University of Rome La Sapienza Hospital were studied. Infants from smoking women 28 years or older show a strong decrease of both PLAP*1/*1 and *2/*2 homozygous types and a marked deviation from Hardy-Weinberg expectation, thus suggesting a different lethal effect of smoke depending on PLAP genotype and maternal age. In infants from smoking mothers there is a decrease of birthweight that is much less evident and statistically not significant in infants carrying the PLAP*1/*1 genotype as compared to other genotypes. The difference between PLAP genotypes concerning birthweight is more marked in women older than 28 years than in younger ones. This suggests that the effects of smoke on birthweight are also dependent on PLAP and maternal age.

Adult↗
PubMed1979

Regulation of alkaline phosphatase expression in human choriocarcinoma cell lines.

The coincident expression of two structurally distinct isoenzymes of human alkaline phosphatase was demonstrated in two independently derived gestational choriocarcinoma cell lines. These proteins were shown to have enzymatic, antigenic, and physical-chemical properties resembling those of isoenzymes from term placenta and adult liver. The regulation of these isoenzymes has been studied during the exposure of both cell lines to 5-bromodeoxyuridine and dibutyryl cyclic AMP. The responses of the alkaline phosphatase isoenzymes to these agents have also been compared with the response of another protein phenotypic to placenta, the alpha subunit of chorionic gonadotropin. The results show that (i) the separate structural genes coding for placental and liver alkaline phosphatases are regulated in a noncoordinate fashion; (ii) both alkaline phosphatase genes respond independently of the alpha subunit; and (iii) the induction of the placental type isoenzyme occurs via at least two independent pathways.

Alkaline Phosphatase↗
PubMed1978

Developmental change in human intestinal alkaline phosphatase.

Starch gel electrophoresis and inhibition studies with L-phenylalanine, L-homoarginine, L-leucine, L-leucylglycylglycine, and L-phenylalanylglycylglycine were carried out on a series of human alkaline phosphatases [orthophosphoric-monoester phosphohydrolase (alkaline optimum); EC 3.1.3.1] derived from fetal and adult liver, kidney, bone, and intestine. No differences between adult and fetal liver, kidney, or bone alkaline phosphatases were observed by either electrophoretic or inhibition studies. However, the fetal intestinal enzyme could be clearly distinguished from the adult intestinal enzyme by its greater anodal electrophoretic mobility and its retardation after treatment with neuraminidase. Even after extensive neuraminidase treatment, its anodal mobility was still slightly greater than that of adult intestinal alkaline phosphatase. Fetal and adult intestinal enzymes showed the same inhibition profiles with the series of inhibitors both before and after treatment with neuraminidase. A survey of intestinal samples from fetuses and premature infants of various gestational ages indicated that the changeover from the synthesis of fetal to adult intestinal enzyme begins at about 28-32 weeks of gestation. The difference between the fetal and adult forms of intestinal alkaline phosphatase may represent the expression of different gene loci or a difference in post-translational modification.

Aging↗
PubMed1975

Affinity-chromatography purification of alkaline phosphatase from calf intestine.

A crude preparation of alkaline phosphatase (EC 3.1.3.1) from calf intestinal mucosa was purified by affinity chromatography on Sepharose-bound derivatives of arsanilic acid, which was found to be a competitive inhibitor of the enzyme. Three biospecific adsorbents were prepared for the chromatography, and the best results were obtained with a tyraminyl-Sepharose derivative coupled with the diazonium salt derived from 4-(p-aminophenylazo)phenylarsonic acid. Alkaline phosphatase was the only enzyme retained by the affinity column in the absence of Pi. The enzyme eluted by phosphate buffer had a specific activity of about 1200 units per mg of protein at pH 10.0, with 5.5mM-p-nitrophenyl phosphate as the substrate.

Adsorption↗
PubMed2003

Effect of the phosphodiesterase 4 inhibitor, rolipram, on retinoic acid-increased alkaline phosphatase activity in the mouse fibroblastic C3H10T1/2 cell line.

We have evaluated effects of a phosphodiesterase (PDE) 4 inhibitor on retinoic acid-increased alkaline phosphatase activity in the mouse fibroblastic C3H10T1/2 clone 8 (10T1/2) cell line. 10T1/2 cells were cultured in minimum essential medium (MEM) and 10% fetal bovine serum with or without 1 microM retinoic acid and/or the PDE 4 inhibitor, rolipram, and harvested at specific intervals before measurement of alkaline phosphatase activity, cAMP production in response to parathyroid hormone, osteocalcin synthesis and expression, and phosphodiesterase activity. Retinoic acid-increased alkaline phosphatase activity, and slightly enhanced cAMP production in response to parathyroid hormone. However, it did not affect osteocalcin synthesis and expression. In the presence of retinoic acid, PDE 4 activity was not changed. A PDE 4 inhibitor, rolipram, and cAMP analog, 8-bromo-cAMP dramatically increased retinoic acid's ability to induce alkaline phosphatase activity. This is the first report that PDE 4 may be involved in regulation of retinoic acid-increased alkaline phosphatase activity.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2006

Serum alkaline phosphatase isoenzyme activities in canine malignant mammary neoplasms with and without osseous transformation.

BACKGROUND: Increased serum activity of total alkaline phosphatase (TALP) has been found in dogs with mammary neoplasms, especially malignant mixed tumors. We hypothesized that the bone isoenzyme of alkaline phosphatase (BALP), a specific indicator of osteoblastic activity and bone formation, may contribute to increased TALP in dogs with mammary neoplasms with osseous transformation. OBJECTIVE: The purpose of this study was to compare serum TALP, BALP, and other ALP isoenzyme activities in dogs with mammary malignant neoplasms with and without osseous transformation. METHODS: Twenty-one female dogs with malignant mammary neoplasms were compared with 21 clinically healthy, age-matched female control dogs. Physical, clinicopathologic (including preprandial and postprandial serum bile acids, ACTH stimulation, and low-dose dexamethasone suppression tests), radiographic, and ultrasonographic examinations were performed on all dogs with tumors to assess coexisting conditions. On the basis of histologic examination of excised tumors, dogs were further classified as having epithelial (n = 11) or mesenchymal/mixed (epithelial-mesenchymal) (n = 10) neoplasms, the latter of which had histologic and radiologic evidence of bone formation. Serum TALP, BALP, liver alkaline phosphatase (LALP), and corticosteroid-induced alkaline phosphatase (CALP) activities were measured using biochemical methods. RESULTS: Dogs with malignant mammary tumors had significantly higher (P < .05) median serum TALP (170 U/L), BALP (59 U/L), LALP (49 U/L), and CALP (24 U/L) activities, compared with control dogs (81, 32, 37, and 5 U/L, respectively). Significantly higher activities of BALP and LALP were found in dogs with epithelial neoplasms; whereas, only CALP activity was higher in dogs with mesenchymal/mixed neoplasms. There was no significant difference in TALP or isoenzyme activitities between epithelial and mesenchymal/mixed groups. CONCLUSION: BALP activity is increased in some dogs with malignant mammary tumors but does not account for the increase in TALP in dogs with neoplasms that have osseous transformation.

Alkaline Phosphatase↗
PubMed1989

The source of serum alkaline phosphatases in liver-tumour-bearing rats.

Patients with hepatic tumours have increased serum activities of alkaline phosphatases. In order to clarify the origin of the increased enzyme activity, two experimental models of rat liver carcinogenesis were studied. In one model, the resistant hepatocyte model, the process was initiated by diethylnitrosamine (DEN, 200 mg/kg), and preneoplastic liver nodules were selected for by 2 weeks of 2-acetylaminofluorene (2-AAF, 0.02%) feeding and partial hepatectomy (PH). High activities of serum alkaline phosphatases were found in these rapidly growing nodules harvested at the peak time of nodular mass expansion. In the other model in which nodules were induced with long-term intermittent feeding of a diet containing 0.05% 2-AAF and harvested in a late stage with a low increase of nodular liver cell mass, no such increase in serum alkaline phosphatase activity was found. A similar difference was also noted when measuring the activities of the enzyme in the nodular tissue. Thus the first model showed high activities of the enzyme in the nodular tissue, while the second model had similar activities to those of the control animals. The serum levels reflected the nodular enzyme activity in both models. The tissue surrounding the nodules did not show increased enzyme activity. No difference was noted in the serum or tissue activity of transaminases. In both models the liver nodules occupied 30-50% of the liver volume. The experimental models were selected to emphasize the importance of the rate of intrahepatic mass expansion for the levels of serum alkaline phosphatase activities.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1968

Secretion of alkaline phosphatase subunits by spheroplasts of Escherichia coli.

Under conditions that permitted continued protein synthesis, spheroplasts of Escherichia coli were unable to form active alkaline phosphatase, although they synthesized protein that was antigenically related to alkaline phosphatase subunits. This cross-reacting protein was primarily detected in the medium of the spheroplast culture, and it had properties that closely resembled those of the alkaline phosphatase subunit. These results suggest that formation of the active alkaline phosphatase dimer by intact E. coli cells proceeds by a pathway in which inactive subunits released from polyribosomes diffuse through the bacterial cell membrane to a periplasmic space where subsequent dimerization to active enzyme occurs. This pathway provides a possible mechanism for the specific localization of this enzyme to the E. coli periplasmic space.

Alkaline Phosphatase↗
PubMed1986

Correlation between serum alkaline phosphatase activity and blood glucose levels.

Fasting blood glucose levels and serum alkaline phosphatase activity of age-matched Libyan diabetic men (168) and women (168) were determined. The mean levels of blood glucose of men and women were 227 +/- 6 and 237 +/- 5 mg/dl, respectively. The respective values of serum alkaline phosphatase were 179 +/- 5 and 199 +/- 6 IU/l. The mean serum phosphatase activity of women was significantly higher (p less than 0.001) than that of their male counterparts. A statistically significant positive correlation was found between serum alkaline phosphatase and blood glucose levels of these diabetic patients (r = 0.35; p less than 0.001).

Adult↗
PubMed1974

Catalytic properties of alkaline phosphatase from pig kidney.

The enzymic properties of alkaline phosphatase (EC 3.1.3.1) from pig kidney brush-border membranes were studied. 1. It hydrolyses ortho- and pyro-phosphate esters, the rate limiting step (V(max.)) being independent of the substrate. It transphosphorylates to Tris at concentrations above 0.1m-Tris. 2. The pH optimum for hydrolysis was between 9.8 and 10. The pK of the enzyme-substrate complex is 8.7 for p-nitrophenyl phosphate and beta-glycerophosphate. Excess of substrate inhibits the enzymic activity with decreasing pH. The pK of the substrate-inhibited enzyme-substrate complex, 8.7, is very similar to that for the enzyme-substrate complex. The pK values of the free enzyme appear to be 8.7 and 7.9. 3. Inactivation studies suggest that there is an essential tyrosine residue at the active centre of the enzyme. 4. The energy of activation (E) and the heat of activation (DeltaH) at pH9.5 showed a transition at 24.8 degrees C that was unaffected by Mg(2+). 5. Kinetic and atomic-absorption analysis indicated the essential role of two Zn(2+) ions/tetrameric enzyme for an ordered association of the monomers. Zn(2+) in excess and other bivalent ions compete for a second site with Mg(2+). Mg(2+) enhances only the rate-limiting step of substrate hydrolysis. 6. Amino acid inhibition studies classified the pig kidney enzyme as an intermediate type of previously described alkaline phosphatases. It has more similarity with the enzyme from liver and bone than with that from placenta.

Alkaline Phosphatase↗
PubMed1992

Differential release of human intestinal alkaline phosphatase in duodenal fluid and serum.

Human intestinal alkaline phosphatase (IAP) can be released by the enterocyte into duodenal fluid as a mixture of three isoforms. A proportion of the enzyme is associated with triple-layered membrane vesicles (vesicular IAP). Although, occasionally, free hydrophilic IAP dimers are present, the remaining enzyme usually consists of a mixture of hydrophobic IAP dimers and more complex hydrophobic IAP structures of larger size, both entities being identified as "intestinal variant" alkaline phosphatase (VAR IAP). The hydrophobicity of VAR IAP stems exclusively from its attached glycosyl-phosphatidylinositol (GPI) anchor. Both vesicular IAP and VAR IAP are converted to hydrophilic enzyme upon removal of the GPI tail by phospholipase D (PLD) present in duodenal fluid. The IAP released into the vascular bed consists mainly of VAR IAP; vesicular IAP is absent. The enzyme characteristics of VAR IAP partially purified from duodenal fluid and from serum are identical. In plasma, VAR IAP appears to associate with (lipo)protein complexes and is thus protected from further degradation by plasma PLD. Such complex formation may explain why, in the serum of a healthy reference population, VAR IAP was more abundant than hydrophilic dimeric IAP.

Alkaline Phosphatase↗