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PubMed1976

Bile canalicular alkaline phosphatase and disease.

The alkaline phosphatase reaction is normally absent in human bile canaliculi, but was found in 79 patients. In search for a common causal factor, these patients were further examined. Thirty-seven were autopsied. The conditions most ocmmonly associated with the phenomenon were malignant tumours with or without involvement of the liver, collagen diseases, long-standing partial obstruction of the common bile duct, and genetic variants of alpha-1-antitrypsin. No clinical or laboratory facts were common to all the patients.

Adolescent↗

PubMed1982

The effect of 1,25(OH)2D3 on alkaline phosphatase in osteoblastic osteosarcoma cells.

The effects of 1,25-dihydroxyvitamin D3 on growth, cell protein, and alkaline phosphatase were examined in cultures of a clonal osteoblast-like rat osteosarcoma cell line at different stages of phenotypic maturation, defined by the level of alkaline phosphatase activity. In "immature" cultures with low alkaline phosphatase specific activity, 1,25-dihydroxyvitamin D3 at 10(-8)-10(-7) M inhibited cell growth and elevated alkaline phosphatase activity; lower hormone concentrations had no effect. In cultures with higher alkaline phosphatase activity, the hormone had biphasic effects: at concentrations of 10(-8)-10(-7) M, 1,25-dihydroxyvitamin D3 inhibited growth and elevated alkaline phosphatase and total cell protein; however, lower hormone concentrations (10(-10) and 10(-9) M) reduced alkaline phosphatase activity. This effect was more pronounced in more "mature" cultures where half-maximum inhibition of alkaline phosphatase activity occurred near 10(-11) M. At this stage, the hormone caused a small increase in cell number. The data suggest that 1,25-dihydroxyvitamin D3 exerts differential effects on skeletal cells depending on their state of growth or maturation. This finding may offer new insights into the effects of 1,25-dihydroxyvitamin D3 on bone and may help resolve apparently conflicting experimental findings on the effects of the hormone on osteoblast-like cells in culture.

Alkaline Phosphatase↗

PubMed1994

[Relation between age of mice and activity and characteristics of serum alkaline phosphatase].

Characteristics of serum alkaline phosphatase (SAP) were investigated in five strains of young and old mice (C57BL/6, BALB/c, C3H/Bi, MRL/Ipr, Ipr, NZB). SAP activity was measured and SAP kinetics was automatically measured by a spectrophotometer. The heat stability and the inhibitor, beta-bromotetramisole, sensitivity of SAP were also determined. Activity of SAP in old mice was significantly lower compared to young mice of the same strain (P < 0.01). SAP of young mice was more heat labile and was more sensitive to inhibitor as compared to SAP of old mice.

Aging↗

PubMed1989

Chromatographic separation of alkaline phosphatase from dental enamel.

Alkaline phosphatase (AP) was prepared from partly mineralized bovine enamel by extraction in phosphate buffer, centrifugation and various chromatographic techniques. Chromatofocusing showed that the enamel enzyme possessed five isoelectric points at the acid pH level ranging from pH 5.7 to pH 4.4. Three enzyme peaks were eluted using low pressure chromatography with a Bio-gel column. With a HPLC gel filtration column the separation of the enamel extract resulted in only one peak with AP activity. The fractions of this peak were used to produce an antibody against bovine AP.

Alkaline Phosphatase↗

PubMed1982

Monomeric alkaline phosphatase of Vibrio cholerae.

Alkaline phosphatase has been purified to homogeneity from two strains of Vibrio cholerae. The enzymes from both strains are single polypeptides of molecular weight 60,000. Both of the enzymes have pH optima around 8.0 and can act on a variety of organic phosphate esters, glucose-1-phosphate being the best substrate. The enzymes are unable to hydrolyze ATP and AMP. Although they have identical Km values, the two enzymes differ significantly in Vmax with p-nitrophenyl phosphate as substrate. The enzymes from the two strains also differ in their sensitivity to EDTA, Pi, and metal ions and activities of the apoenzymes. Ca2+ reactivated the apoenzymes most.

Alkaline Phosphatase↗

PubMed1984

Alkaline phosphatase activity in non-Hodgkin's lymphomas and pseudolymphomas of the skin.

Alkaline phosphatase enzyme activity was studied histochemically in 60 non-Hodgkin lymphomas and 10 pseudolymphomas of the skin. Among the 37 B-cell lymphomas, membrane-bound alkaline phosphatase activity was demonstrated in 8 cases. In none of the 23 cutaneous T-cell lymphomas studied could membrane-bound alkaline phosphatase be detected. Among the pseudolymphomas, 2 cases revealed alkaline phosphatase activity. It was not possible to draw any particular clinically significant conclusions from the membrane-bound alkaline phosphatase reactions. Looking for the microenvironmental conditions of lymphoproliferative processes in the skin, alkaline phosphatase-positive capillaries were seen predominantly in the T-cell lymphomas. The stromal reaction showing a proliferation of alkaline phosphatase-positive fibroblasts was more pronounced in cutaneous B-cell lymphomas. In conclusion, membrane-bound alkaline phosphatase in lymphoproliferative processes in the skin, as in the lymph node, characterize a distinct group of B lymphocytes related to follicle center cells. The clinical relevance of this finding remains to be determined.

Alkaline Phosphatase↗

PubMed1984

Purification and characterization of four different alkaline phosphatases from Spirographis spallanzanii.

Alkaline phosphatases (APs) present in Spirographis spallanzanii were extracted by water homogenization of butanol treatment. The enzymes solubilized as above were purified by acetone fractionation and then by DEAE-cellulose and Sephadex G-200 chromatography; separation of four AP forms was achieved, which were characterized by studying their molecular and catalytic properties. The various APs differ in molecular weight, electrophoretic mobility, optimum pH, but show similar Km values and substrate inhibition pattern. Kinetic studies carried out with several inhibitors show, in particular, the existence in these APs of a second binding site and suggest a possible role for them in the metabolism of phosphoric esters of the sugars.

Alkaline Phosphatase↗

PubMed2003

Purification and characterization of Ulva pertusa Kjellm alkaline phosphatase.

The activity of alkaline phosphatase (ALP, EC 3.1.3.1.) was found in seaweeds, including five kinds of green alga, eighteen kinds of red alga, and six kinds of brown alga, collected from the seaside of Dalian in China. The enzyme was purified 1230-fold from Ulva pertusa Kjellm. It had a specific activity of 48.6 U/mg protein and was proven to be homogeneous by SDS-PAGE with a subunit molecular mass of 19.5 kDa. The activity of ALP peaked at pH9.8, and was completely inhibited by DTT and partly by NBS. The Michaelis-Menten constant Km and the maximum reaction velocity Vmax, at pH 9.8 and 37 degrees C were 0.950 mM and 5.00 microM/min, respectively.

Alkaline Phosphatase↗

PubMed1987

Resistance to inactivation by EGTA of the enzyme-substrate and enzyme-phosphate complexes of alkaline phosphatase.

Bovine intestinal mucosal alkaline phosphatase is inactivated by the chelating agent EGTA. Several concentrations of the enzyme were incubated with EGTA and a range of concentrations of the substrate p-nitrophenyl phosphate to determine the substrate concentration as a function of time. As predicted by a recently developed theory [Duggleby (1986) J. Theor. Biol. 123, 67-80], catalysis ceases before all substrate is exhausted. An analysis of these final substrate concentrations according to the theory revealed that, whereas the free enzyme is unstable, the effect of EGTA is counteracted when either the substrate or product (phosphate) is bound. Comparison of the results with those obtained by direct stability measurements and steady-state kinetic experiments gave a qualitatively and quantitatively consistent body of evidence in support of this interpretation.

Alkaline Phosphatase↗

PubMed1981

Synthesis and secretion of alkaline phosphatase in vitro from first-trimester and term human placentas.

The synthesis and secretion of alkaline phosphatases in vitro by human placental tissue incubated in organ culture were studied. First-trimester placenta synthesizes and secretes two different alkaline phosphatase isoenzymes (heat-labile and heat-stable), whereas in term placenta nearly all the alkaline phosphatase synthesized and secreted is heat-stable. The specific activities of alkaline phosphatases in first-trimester and term placental tissue remain constant throughout the time course of incubation. In the media, specific activities increase with time. Hence, alkaline phosphatase synthesis seems to be the driving force for its own secretion. The rates of synthesis de novo and of alkaline phosphatases were measured. The specific radioactivities of the secreted alkaline phosphatases were higher than the corresponding specific radioactivities in the tissue throughout the entire incubation period. The intracellular distribution of the alkaline phosphatase isoenzymes was compared.

Alkaline Phosphatase↗

PubMed1997

Paraneoplastic elevation of serum alkaline phosphatase in renal cell carcinoma: incidence and implication on prognosis.

PURPOSE: We investigated the incidence and prognostic significance of paraneoplastic elevation of serum alkaline phosphatase in patients with renal cell carcinoma. MATERIALS AND METHODS: Clinical data of 365 pathologically proved renal cell carcinoma cases were reviewed. Serum alkaline phosphatase level greater than 100 units per 1., but without obvious conditions that may cause phosphatase elevation, including metastasis to or disease of liver or bone and pregnancy, was regarded as paraneoplastic serum alkaline phosphatase elevation. Survival was evaluated using the Kaplan-Meier method. RESULTS: Of 365 patients 77 (21.1%) had paraneoplastic serum alkaline phosphatase elevation. The respective incidence from stage I to IV cases was 9.9% (16 of 161), 31.9% (15 of 47), 34.3% (23 of 67) and 25.6% (23 of 90). Patients with stage I disease had the lowest incidence but there were no statistically significant differences among stages II, III and IV disease. Of 77 patients with elevated serum alkaline phosphatase 48 had additional paraneoplastic manifestations. The disease specific 5-year survival rate in patients with normal serum alkaline phosphatase was significantly better than in patients with isolated phosphatase elevation, which in turn was better than in patients with multiple paraneoplastic syndromes (70.7 versus 50.5 versus 30.8%). Patients with persistent or recurrent elevation of serum alkaline phosphatase after radical nephrectomy had metastatic lesion or local recurrence. In some patients serum alkaline phosphatase returned to normal after nephrectomy but metastasis developed later without recurrent phosphatase elevation. CONCLUSIONS: Paraneoplastic serum alkaline phosphatase elevation in renal cell carcinoma patients implies an unfavorable prognosis, and additional paraneoplastic syndromes further worsen the prognosis. Recurrent or persistent serum alkaline phosphatase elevation after radical nephrectomy suggests distant metastasis or residual tumor. However, the return of serum alkaline phosphatase to normal does not guarantee cure of the disease. Identification of paraneoplastic serum alkaline phosphatase elevation is valuable in the prediction of outcome and postoperative followup of renal cell carcinoma patients.

Alkaline Phosphatase↗

PubMed2003

Accelerated fat absorption in intestinal alkaline phosphatase knockout mice.

Intestinal alkaline phosphatase (IAP) is the most ancestral of the tissue-specific members of the AP gene family. Several studies have suggested an absorptive function for IAP, but in vivo data to this effect have been lacking. We inactivated the mouse IAP gene in embryo-derived stem cells and generated mice homozygous for the null mutation. The mice were macroscopically and histologically normal and fertile and showed no difference from the wild-type controls under normal laboratory conditions. However, when maintained long-term on a high-fat diet, the IAP-deficient mice showed faster body weight gain than did control animals. Histological examination revealed an accelerated transport of fat droplets through the intestinal epithelium and elevation of serum triglyceride levels in the IAP-deficient mice compared to wild-type mice. Our study suggests that IAP participates in a rate-limiting step regulating fat absorption.

Alkaline Phosphatase↗

PubMed1988

Homodimer and heterodimer forms of adult rat intestinal alkaline phosphatase.

Three forms of alkaline phosphatase have been isolated from different sections of the small intestine: F3 180 kDa from the duodenum; F2 150 kDa principally jejunal; F1 120 kDa the only ileal form. Their catalytic properties have been compared as well as the electrophoretic properties the dimer and monomer of their phosphorylated intermediates. Pi was a competitive inhibitor of F1 and F3, whereas glycerophosphate was competitive inhibitor only of F3. Pi was a non competitive inhibitor of F2 and of a mixture F1 plus F3. Heating the phosphorylated enzyme preparations led to their dissociation into the phosphorylated monomers: F1 and F3 appear to be homodimers 65 kDa and 90 kDa peptides respectively whilst F2 seems to be a dimer formed from one of each monomer. F1 was phosphorylated faster but less intensively than F3. F2 was strongly phosphorylated over a long time-course and its 65 kDa monomer fraction was phosphorylated more strongly for longer than that from F1.

Alkaline Phosphatase↗

PubMed1990

Antigenicity of adult Schistosoma mansoni alkaline phosphatase.

Antibodies to the alkaline phosphatase (AP) of Schistosoma mansoni in infected human and mice sera were evaluated by a direct solid-phase AP immunoadsorption assay (APIA) and by Western blot and immunostaining. APIA consisted of (a) solid-phase capture of immunoglobulins from infected human or mice, (b) immunoadsorption of the enzyme antigen by the antibodies, and (c) detection of the enzymatic activity. By this procedure the appearance of the anti-AP response in mice was detected around 50 days post-infection; this response was not specific for an AP of a given schistosome strain and it was not induced by an autoimmunity phenomenon. Fourteen out of 15 sera from infected people tested by APIA showed a clear antibody response against this enzyme. Immunoblots in non-reducing conditions supported APIA results indicating that the parasite AP was specifically recognized by the antibodies present in infected human and mice sera. These results suggest the possible usefulness of the schistosome AP as a marker for S. mansoni infection.

Alkaline Phosphatase↗

PubMed1984

Properties of an alkaline phosphatase from Sinclair swine melanoma.

In Sinclair swine, there is an increase in alkaline phosphatase activity in spontaneously arising melanoma tumors when compared to normal skin. While alkaline phosphatase activity could be detected in melanomas from animals 1 day old, the maximum levels of alkaline phosphatase activity occurred in tumors from animals greater than 30 days old. The alkaline phosphatase was purified from cutaneous melanomas using chloroform precipitation, Phenyl-Sepharose chromatography, and concanavalin A Sepharose chromatography approximately 146-fold, with an overall recovery of 15%. The purified enzyme exhibited optimal activity over the pH range of 8.9-10.6. The apparent Km of the enzyme for p-nitrophenyl phosphate was 0.15 mM. The enzyme exhibited a relative mobility of 0.04 in nondenaturing polyacrylamide gels. The molecular weight of the enzyme was estimated by gel filtration chromatography to be 122,000 and it was composed of two identical subunits each having a molecular weight of 67,000. The enzyme was thermolabile at 56 degrees C (T50, 18 min) and its activity was inhibited by L-homoarginine, levamisole, and vanadate, but not by L-phenylalanine or L-phenylalanylglycylglycine. These characteristics distinguished the enzyme from the intestinal isoenzyme that is found in normal swine skin but were similar to those exhibited by the porcine placental isoenzyme of alkaline phosphatase. These results suggest that the development of malignant melanoma in Sinclair swine is accompanied by the expression of a placental-like alkaline phosphatase activity.

Alkaline Phosphatase↗

PubMed1990

Enzyme immunoassay of human placental and germ-cell alkaline phosphatase in serum.

Placental alkaline phosphatase (placental ALP, PLAP) and germ-cell ALP (GCAP, also known as placental-like ALP), expressed in gonadal cancer tissues, are potential tumor markers. Four monoclonal antibodies, raised against PLAP and recognizing different epitopes, were selected to study the influence of the following variables on the accuracy of PLAP and GCAP measurement: phenotype, molecular form, and glycation pattern of PLAP and GCAP; incubation temperature; and interferences by serum during immunobinding. Nine GCAP phenotypes were identified, interacting with each antibody at a lower affinity than was seen for the more common PLAP phenotypes. Antibody affinity is higher for the free hydrophilic dimeric forms of PLAP and GCAP, and is not influenced by the degree of glycation. In serum or tissue extracts, measurement of PLAP or GCAP is most nearly accurate when immunoincubations are performed at 37 degrees C, with use of antibodies 327 and 7E8, respectively. In addition, correct measurements are achieved only when, during immunobinding, serum is incubated with an equal volume of deoxycholate (9 g/L final concentration).

Alkaline Phosphatase↗

PubMed2002

Identification of histidine residues at the active site of Megalobatrachus japonicus alkaline phosphatase by chemical modification.

Alkaline phosphatase from Megalobatrachus japonicus was inactivated by diethyl pyrocarbonate (DEP). The inactivation followed pseudo-first-order kinetics with a second-order rate constant of 176 M(-1) x min(-1) at pH 6.2 and 25 degrees C. The loss of enzyme activity was accompanied with an increase in absorbance at 242 nm and the inactivated enzyme was re-activated by hydroxylamine, indicating the modification of histidine residues. This conclusion was also confirmed by the pH profiles of inactivation, which showed the involvement of a residue with pK(a) of 6.6. The presence of glycerol 3-phosphate, AMP and phosphate protected the enzyme against inactivation. The results revealed that the histidine residues modified by DEP were located at the active site. Spectrophotometric quantification of modified residues showed that modification of two histidine residues per active site led to complete inactivation, but kinetic stoichiometry indicated that one molecule of modifier reacted with one active site during inactivation, probably suggesting that two essential histidine residues per active site are necessary for complete activity whereas modification of a single histidine residue per active site is enough to result in inactivation.

Alkaline Phosphatase↗

PubMed1986

Molecular cloning and sequence analysis of human placental alkaline phosphatase.

The complete amino acid sequence of the precursor and mature forms of human placental alkaline phosphatase have been inferred from analysis of a cDNA. A near full-length PLAP cDNA (2.8 kilobases) was identified upon screening a bacteriophage lambda gt11 placental cDNA library with antibodies against CNBr fragments of the enzyme. The precursor protein (535 amino acids) displays, after the start codon for translation, a hydrophobic signal peptide of 21 amino acids before the amino-terminal sequence of mature placental alkaline phosphatase. The mature protein is 513 amino acids long. The active site serine has been identified at position 92, as well as two putative glycosylation sites at Asn122 and Asn249 and a highly hydrophobic membrane anchoring domain at the carboxyl terminus of the protein. Significant homology exists between placental alkaline phosphatase and Escherichia coli alkaline phosphatase. Placental alkaline phosphatase is the first eukaryotic alkaline phosphatase to be cloned and sequenced.

Alkaline Phosphatase↗