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PubMed1995

Okadaic acid inhibits alkaline phosphatase activity in MC3T3-E1 cells.

Alkaline phosphatase activity is regulated by various hormones and growth factors at least in part through the phosphorylation of target proteins during the bone cell differentiation. To investigate the role of protein phosphorylation in alkaline phosphatase activity in MC3T3-E1 osteoblast, we used okadaic acid which is a potent specific inhibitor of serine/threonine protein phosphatases to type 1 and 2A. Alkaline phosphatase activity in cellular layer was measured by spectrophotometer using p-nitrophenyl phosphate as substrate and data were expressed as p-nitrophenyl of nmol/min/mg of protein. Okadaic acid (1-50 ng/ml) caused the inhibition of alkaline phosphatase activity in MC3TC-E1 cells. At 50 ng/ml of okadaic acid showed the maximal inhibitory effect on alkaline phosphatase activity. Okadaic acid (50 ng/ml) also inhibited alkaline phosphatase activity in all differentiation stages. These results indicate that okadaic acid inhibits alkaline phosphatase activity in MC3T3-E1 cells.

Alkaline Phosphatase↗
PubMed1981

Purification and initial characterization of intrinsic membrane-bound alkaline phosphatase from chicken epiphyseal cartilage.

Alkaline phosphatase has been purified from microsomes of chicken epiphyseal cartilage by first selectively extracting certain adventitious proteins with 0.25 M trichloroacetate. The membrane-bound enzyme was then solubilized by 1% cholate in buffered 33% saturated ammonium sulfate and purified by column chromatography on Bio-Gel A-5m, extraction with 1-butanol, and ion exchange chromatography on DEAE-Bio-Gel A. The purified alkaline phosphatase from the cartilage membrane had a subunit molecular weight of 53,000 and a holoenzyme weight of 207,000-220,000, indicating a tetramer. The pH optima for p-nitrophenylphosphate, ATP, and pyrophosphate hydrolysis were 10.3, 9.0, and 8.5, respectively. Values of Vmax (in micromoles/min/mg) were 220, 3.1, and 0.8, respectively. Substrate inhibition was pronounced at values of pH below 8.5. Inhibition of p-nitrophenylphosphate hydrolysis at pH 10.3 showed that phosphate and arsenate were competitive inhibitors (KI = 1.88 and 0.15 mM, respectively) and levamisole was an uncompetitive inhibitor (KI = 0.32 mM), while L-phenylalanine and ZnCl2 were mixed inhibitors (KI = 15.8 and 0.02 mM, respectively). Inhibition by preincubation in 1 mM EDTA was reversible by readdition of 0.25 mM MgCl2 nd 20 microM ZnCl2. The data indicate that this membrane-bound alkaline phosphatase from chicken epiphyseal cartilage is a Zn2+ and possibly Mg2+-containing enzyme. While the subunit molecular weight and kinetic properties of the enzyme are quite typical of vertebrate alkaline phosphatases, the tightness of binding to the membrane lipids, the extreme sensitivity to substrate inhibition, and the tetrameric conformation of the holoenzyme are unusual.

Alkaline Phosphatase↗
PubMed1992

Advanced prostate cancer follow-up with prostate-specific antigen, prostatic acid phosphatase, osteocalcin and bone isoenzyme of alkaline phosphatase.

We report our experience in the follow-up of 63 patients with advanced prostate adenocarcinoma. We used prostate-specific antigen and prostatic acid phosphatase in 27 patients; in 36 patients we evaluated osteocalcin and bone isoenzyme of alkaline phosphatase, two markers of bone metabolism which seem to be good markers in the follow-up of patients with bone metastases.

Acid Phosphatase↗
PubMed1990

Use of metal chelate affinity chromatography for removal of zinc ions from alkaline phosphatase from Escherichia coli.

Alkaline phosphatase from Escherichia coli (APEC) is not retained at 4 degrees C on a metal-free tris(carboxymethyl)ethylenediamine (TED) column, but at 15 degrees C the metalloenzyme becomes bound to the gel. Chromatography of phosphatase on metal-free TED gel indicates a decline in its enzymic activity and zinc content to about 26% and 40%, respectively. The activity of chromatographed APEC can be partially restored by addition of zinc ions, indicating that metal-free TED gel is capable of removing zinc ions from alkaline phosphatase.

Alkaline Phosphatase↗
PubMed2004

Identification of the gene for the monomeric alkaline phosphatase of Vibrio cholerae serogroup O1 strain.

Alkaline phosphatase (APase) of Vibrio cholerae is the first monomeric alkaline phosphatase reported [Roy, N.K., Ghosh, R.K., Das, J., 1982a. Monomeric alkaline phosphatase of V. cholerae. J. Bacteriol. 150, 1033-1039.]. The gene (phoA(VC)) encoding this enzyme is not identified in the published genome sequence of the V. cholerae serogroup O1 El Tor strain N16961 [Heidelberg et al., 2000, DNA sequence of both the chromosome of cholera pathogen V. cholerae. Nature 406, 477-484.]. However two genes (phoB(VC) and phoR(VC)) regulating the synthesis of alkaline phosphatase in this organism, equivalent to phoB and phoR of Escherichia coli, are located in tandem on chromosome I of V. cholerae. We have identified the phoA(VC) gene on the N16961 genome sequence by amino acid sequence analysis of the purified alkaline phosphatase of V. cholerae classical strain 569B followed by BLAST search. The gene was found to be located on the hypothetical protein locus VCA0033 of chromosome II. The identity of the gene was confirmed by expressing the cloned VCA0033 locus in phoA mutant E. coli E15 and JC9223 cells and isolating V. cholerae monomeric alkaline phosphatase. Insertional inactivation of the gene also resulted in complete loss of the phenotype. Unlike in E. coli where phoB, phoR and phoA are closely linked, phoA(VC) is not linked to phoB(VC) and phoR(VC).

Alkaline Phosphatase↗
PubMed2002

An infrared study of the thermal and pH stabilities of the GPI-alkaline phosphatase from bovine intestine.

Alkaline phosphatase (EC 3.1.3.1) from bovine intestine mucosa (BIAP) is a homodimeric metalloenzyme, which hydrolyses nonspecifically phosphate monoesters at alkaline pH with release of inorganic phosphate and alcohol. BIAP is either soluble (sBIAP) or membrane-anchored by a glycosylphosphatidylinositol moiety (GPI-BIAP). This anchor might have some contribution in the stabilization of the GPI-linked protein structure. Our purpose was to study the role of the anchor by using two parameters, the enzymatic activity and the protein conformation, which was analyzed by using FTIR spectroscopy. We determined that the two forms of BIAP show some similarities with the previously described structure of alkaline phosphatase isolated from Escherichia coli and human placenta. Meanwhile GPI-BIAP and sBIAP exhibit similar specific activities, the presence of the anchor increases the thermal and pH stabilities of the enzyme activity and conformation.

Alkaline Phosphatase↗
PubMed1994

N omega-phosphoarginine phosphatase from rat renal microsome was alkaline phosphatase.

Activity hydrolyzing both N omega-phosphoarginine and glucose-6-phosphate was detected in rat renal microsome but not in hepatic microsome. Renal microsome was solubilized with 1% n-octyl-beta-D-thioglucoside and purified with DEAE-Sepharose column chromatography. Fractions hydrolyzing both N omega-phosphoarginine or glucose-6-phosphate were subjected to 7.5%-polyacrylamide gel electrophoresis in the presence of 0.1% sodium dodecyl sulfate. Phosphatase activity in the gels was detected by a lead nitrate stain using N omega-phosphoarginine or glucose-6-phosphate as substrates. Both substrates produced a stain in the region of the gel corresponding to a protein with a mass of 150 kDa. Extracts of slices from this region of the gel also hydrolyzed phosphocreatine, inorganic pyrophosphate, and O-phosphotyrosine. Moreover, the phosphatase had its optimal pH in the alkaline range and was inhibited completely by 20 microM sodium vanadate, 1 mM cysteine, and 1 mM tetramisole. All these properties indicate that the microsomal phosphoamidase (EC 3.9.1.1) of rat kidney was identical with alkaline phosphatase (EC 3.1.3.1).

Alkaline Phosphatase↗
PubMed1995

Clinical utility of a wheat-germ precipitation assay for determination of bone alkaline phosphatase concentrations in patients with different metabolic bone diseases.

Bone alkaline phosphatase was evaluated by wheat-germ lectin precipitation in several clinical conditions. The study included 33 premenopausal healthy women, 46 postmenopausal apparently healthy women, 19 growing children, 24 patients with Paget's disease, 31 patients with primary hyperparathyroidism and 66 patients with hepatobiliary diseases. In postmenopausal women the mean T score (i.e.: the number of SD below or above the mean for premenopausal women) was 2.6 +/- 1.3 (SD) for bone alkaline phosphatase and 1.61 +/- 1.21 for total alkaline phosphatase (p < 0.001). The T score for bone alkaline phosphatase provided a better discrimination from normals for both Paget's disease (22.1 +/- 27.8 versus 12.8 +/- 16 p < 0.001) and primary hyperparathyroidism (8.2 +/- 4.3 versus 4.6 +/- 3.7 p < 0.005 for bone alkaline phosphatase and total alkaline phosphatase respectively). After treatment with intravenous bisphosphonate the percent decrease of bone alkaline phosphatase was larger than that of total alkaline phosphatase both in patients with Paget's disease (-46% versus -72% p < 0.01) and in patients with primary hyperparathyroidism (-21% versus -47% p < 0.02) and an estimate of the precision (delta mean/SD of the delta mean) for bone alkaline phosphatase was 1.9-3.7 times higher than that of total alkaline phosphatase. In twelve osteoporotic patients treated for six months with oral alendronate the decrease in bone turnover was detected with significantly higher precision with bone alkaline phosphatase than with total alkaline phosphatase (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2002

Lipopolysaccharide administration increases acid and alkaline phosphatase reactivity in the cardiac muscle.

The effect of lipopolysaccharide (LPS) administration on the in situ distribution of the reaction product of acid phosphatase (AcPase) and alkaline phosphatase (AlPase) activity was examined in the rat cardiac muscle using catalytical cytochemistry. Tissues of the heart were fixed and then incubated in reaction media for detection of AcPase and AlPase reactivity. In normal hearts, reaction product of AcPase activity was observed in lysosomes. AlPase reactivity was detected at the extracellular surface of the capillary endothelilal cells and in their caveolae. Following LPS administration, the number and the size of lysosomes possessing AcPase reactivity as well as their electron density significantly increased. Furthermore, they tended to form groups consisting of three to five lysosomes. Cytochemical reaction 2 and 24 hours after injection was similar. One week later, the reaction returned to its normal pattern. As in the case with AcPase, the first changes of the distribution of the reaction product of AlPase activity were detected 2 hours after injection. The changes included a remarkable increase of the number of enzymatically positive capillaries, intensified cytochemical reaction in endothelial cells, and an increased number of caveolae. Again, no noticeable differences in reactivity were observed 2 and 24 hours after injection and the reaction returned to normal one week later. Collectively, our data indicate that both cardiac AcPase and AlPase are affected early after injection of LPS. Although the pattern of cytochemical reaction of both phosphatases was restored one week later, it is believed that the altered distribution of their reactivity in early periods after LPS administration may be a factor contributing to the development of pathological changes in this organ at a later stage.

Acid Phosphatase↗
PubMed1992

Histochemical studies of acid and alkaline phosphatases in rat tooth germs with undecalcified resin-embedded specimens.

A novel technique for the histochemical demonstration of acid phosphatase (AcPase) and alkaline phosphatase (AkPase) in hard tissues has been proposed. Fresh, unfixed, undecalcified samples of rat tooth germs and surrounding structures were embedded in LR Gold resin at -20 degrees C. Sections of 2 microns were taken and subsequently processed for enzyme histochemistry. AkPase reaction product appeared as strong linear staining outlining cell boundaries and was present in the enamel organ, dental pulp, and osteoblast cells. Tartrate-resistant AcPase staining was seen exclusively in the osteoclasts of developing alveolar bone. Our results demonstrated that the use of unfixed, undecalcified LR Gold resin-embedded specimens for histochemistry is a novel technique which may be of value for certain studies when decalcification of specimens is undesirable. The technique appears to give good preservation of enzyme activity combined with the ability to prepare sections with excellent morphological detail.

Acid Phosphatase↗
PubMed1975

Distribution of acid and alkaline phosphatases in canine skin.

Azo dye methods were used to determine the distribution of acid phosphatase (ACP) and alkaline phosphatase (ALP) in the skin of 25 Beagle dogs. ALP activity was found in dermal papillae of hair follicles regardless of their state of activity, in Huxley's layer of the inner root sheath of anagen stages, in myoepithelial cells of apocrine sweat glands, in germinative cells of sebaceous glands, in vascular endothelium, and in mast cells. The ACP activity was found in the epidermis, outer and inner root sheaths, keratogenous zone, hair cuticle and medulla, duct of sebaceous gland, and sebum. The results indicate that ACP and ALP are distinctive enzymes serving different biologic functions. The principal role of ALP in the skin appears to be dephosphorylation for adsorption and transport of chemical substances necessary for growth and maintainence of the pilary system and glandular adnexa. The ACP appears to be primarily involved in the breakdown of phospholipids and in necrobiosis of keratinocytes.

Acid Phosphatase↗
PubMed1978

Activity of acid and alkaline phosphatase in neutrophils of rats exposed to benzene and treated with selenium.

Cytochemical studies on activity of acid phosphatase (AcP) and alkaline phosphatase (AP) in peripheral blood neutrophils of rats chronically exposed to benzene vapours (1,200 mg/cm3) demonstrated that the exposure results in the increase of AcP and the decrease of the AP activity. The changes noted correlate with the time of exposure and are observed even after 5 months after exposure. The administration of sodium selenate in a dose of 1.0 microgram/kg before exposure prevented the above enzymatic alterations caused by benzene. In contrast, the administration of selenium in a dose of 5.0 microgram/kg only prevented the change of AP activity and caused reactive neutrophilic leukocytosis.

Acid Phosphatase↗
PubMed1989

The effect of alkaline phosphatase on platelet aggregation.

Elevated concentrations of alkaline phosphatase occur in a variety of diseases. The effect of alkaline phosphatase on platelet aggregation was tested. Adenosine diphosphate-induced aggregation was inhibited at the highest concentrations of alkaline phosphatase employed. Similar results were observed when epinephrine, collagen and arachidonic acid were used as aggregating agents. A dose-dependent inhibition of ristocetin-induced aggregation by alkaline phosphatase was observed. These results were confirmed using plasma from patients with cholestatic disease and elevated concentrations of alkaline phosphatase similar to those used in the in vitro studies. These data indicate that patients with significantly elevated levels of alkaline phosphatase may be predisposed to a thrombocytopathy.

Adenosine Diphosphate↗
PubMed1985

Serum and tissue alkaline phosphatases in pigs.

The alkaline phosphatases from serum, liver, bone and intestine of pigs were separated by starch and polyacrylamide gel electrophoresis. Treatments with neuraminidase, urea, heat, L-homoarginine and L-phenylalanine were performed. Variants of serum alkaline phosphatases were derived from different tissues and hence must be under the control of at least two different loci. Within the intestinal phosphatases, polymorphic electrophoretic patterns were observed among 195 animals.

Alkaline Phosphatase↗
PubMed1984

Suppression of placental alkaline phosphatase biosynthesis by tunicamycin.

Placental alkaline phosphatase activity and immunoreactivity were inhibited in a parallel fashion in choriocarcinoma cells by tunicamycin, a protein glycosylation inhibitor. Tunicamycin suppressed placental alkaline phosphatase biosynthesis in addition to inhibiting protein glycosylation in general. An anti-placental alkaline phosphatase-precipitable polypeptide of 58,000 daltons was formed in the presence of this antibiotic. The 58,000-dalton polypeptide had a degradation rate similar to that of the glycosylated phosphatase monomer from control cultures. Tunicamycin suppressed placental alkaline phosphatase mRNA activity leading to the observed decrease in biosynthesis.

Alkaline Phosphatase↗
PubMed1986

The clinical use of alkaline phosphatase enzymes.

The enzyme alkaline phosphatase is an important serum analyte and its elevation in serum is correlated with the pressure of bone, liver, and other diseases. The analysis of the isoenzymes of alkaline phosphatase is an aid in diagnosing liver and/or bone disease, especially the high molecular weight isoenzymes that appear in cholestatic liver disease.

Alkaline Phosphatase↗