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PubMed1988

Mapping of gene encoding mouse placental alkaline phosphatase to chromosome 4.

The gene encoding the mouse placental alkaline phosphatase (ALP; orthophosphoric-monoester phosphohydrolase, alkaline optimum, EC 3.1.3.1) is mapped to chromosome 4, based on Southern blot hybridization of the mouse cDNA with DNAs from mouse-Chinese hamster somatic cell hybrids. This assignment is consistent with the genetic analysis of the Akp-2 locus, which is responsible for the genetic variation of alkaline phosphatase enzyme in placenta as well as in liver, kidney, and bone.

Alkaline Phosphatase↗

PubMed1980

Intestinal alkaline phosphatase and the ABO blood group system--a new aspect.

The influence of erythrocytes of different blood groups on the intestinal isoenzyme of alkaline phosphatase (EC 3.1.31.1) was investigated. Binding of the enzyme to erythrocyte membranes was demonstrated by sedimentation experiments, by enzyme electrophoresis, by gel chromatography and immunologically using a modified Coombs technique. We found that red cells of blood group A bind almost all intestinal alkaline phosphatase; erythrocytes of blood group B or O to a much lesser degree. This is in accordance with the fact that intestinal alkaline phosphatase is found more frequently in the serum of individuals of blood group O or B than in serum of persons of blood group A. We conclude that underlying the described blood group dependent differences in synthesis of intestinal alkaline phosphatase lies a mechanism involved in the regulation of the activity of intestinal alkaline phosphatase in human serum.

ABO Blood-Group System↗

PubMed1990

Alkaline phosphatase and phosphoamino acid phosphatases in normal and cancerous tissues of the human larynx.

The activities of alkaline phosphatase and phosphoamino acid phosphatases were measured in normal and cancerous regions of the human larynx. For each larynx, alkaline phosphatase and phosphotyrosine phosphatase activities were higher in the tumor than in the corresponding normal tissue. Phosphothreonine and phosphoserine phosphatase activities were relatively low and there were no consistent trends. The increased alkaline phosphatase activity in the tumors supports histological observations that ossification of cartilage seems to occur at the site of invasion; the phosphatase acting on phosphotyrosine could serve as a regulator of cell differentiation during tumorigenesis.

Adult↗

PubMed2003

Relation of salivary inorganic phosphorus and alkaline phosphatase to the dental caries status in children.

The phosphorus concentration and alkaline phosphatase activity in saliva may be related to the susceptibility to dental caries. Thirty children in the age group of 4-6 years were divided into 3 groups. Group 1, children had rampant caries with dfs>10, group 2- dfs>5<10, group 3 caries free with dfs<1. The unstimulated mixed salivary sample was collected from each child and assayed by biochemical methods to determine the phosphorus and alkaline phosphatase concentration in saliva sample. The results showed that higher alkaline phosphatase activity and phosphorus concentration were associated with rampant caries.

Alkaline Phosphatase↗

PubMed1980

Micro-determination of inorganic phosphorus and alkaline phosphatase activity in biological fluids.

Inorganic phosphorus and alkaline phosphatase activities were measured in serum samples from goats, buffaloes, cows, bullocks and also in amniotic and allantoic fluid of goats using ascorbic acid as reductant for phosphomolybdate. The results were compared with conventional method of FISKE and SUBBAROW (1925). There were no significant differences between the 2 methods. It was possible to measure micro-amounts of inorganic phosphorus and alkaline phosphatase activity with precision even in low cost colorimeters.

Alkaline Phosphatase↗

PubMed1992

Placental alkaline phosphatase is related to human IgG internalization in HEp2 cells.

The biological function(s) of placental alkaline phosphatase has not yet been unraveled. The low catalytic activity of the enzyme at physiological pH, and the lack of "natural substrates", bring about the necessity of a more structure-related conception of its role. We have observed an interaction between placental alkaline phosphatase and human IgG. In this report we show that this isozyme is the major membrane protein able to bind IgG in a IgG-internalizing cell line (HEp2). Pretreatment of these cells with Fab fragments of anti placental alkaline phosphatase antibodies blocks the internalization of IgG without perturbing the endocytosis of other ligands. Our results indicate that placental alkaline phosphatase has the ability not only to bind human IgG, but also to promote its internalization in HEp2 cells.

Alkaline Phosphatase↗

PubMed1989

Influence of non-steroidal anti-inflammatory drugs and disease activity on serum alkaline phosphatase concentrations in rheumatoid arthritis, osteoarthritis, and polymyalgia rheumatica.

The influence of non-steroidal anti-inflammatory drugs (NSAIDs) and of disease activity on the serum alkaline phosphatase concentration was examined in patients with rheumatoid arthritis, osteoarthritis, and polymyalgia rheumatica. Concentrations of serum alkaline phosphatase were similar both in patients with rheumatoid arthritis taking NSAIDs and in those not taking NSAIDs. In patients with osteoarthritis NSAID use was not associated with a significant increase in serum alkaline phosphatase. In rheumatoid arthritis no correlation was found between clinical indices of disease activity and serum alkaline phosphatase concentrations. There was significant correlation with plasma viscosity in rheumatoid arthritis, both in those taking and not taking NSAIDs, and in polymyalgia rheumatica. Serum alkaline phosphatase concentrations are not influenced by NSAIDs. Concentrations correlate with laboratory parameters, but not clinical indices of disease activity.

Aged↗

PubMed1987

Human placental and intestinal alkaline phosphatase genes map to 2q34-q37.

The alkaline phosphatases comprise a multigene enzyme family that hydolyze phosphate esters and are widely distributed in nature. Three main classes have been isolated from humans, the placental, intestinal, and liver/bone/kidney forms. We have mapped the placental and intestinal alkaline phosphatase genes to 2q34-q37 by using chromosomal in situ hybridization and a somatic-cell hybrid panel.

Alkaline Phosphatase↗

PubMed1980

Modern concepts of acid and alkaline phosphatase measurement.

Three new assay methods for prostatic acid phosphatase are described relative to results of biochemical methods. Methods for total and isozymes of alkaline phosphatase are also described. Results of a field trial for acid phosphatase tests among multiple institutions in the United States revealed a marked increase in sensitivity for one assay (CIEP) over biochemical methods. which was positive with increasing frequency as the clinical and surgical stage advanced beyond B. Only for stage D did the biochemical method approach the sensitivity of the CIEP assay. The CIEP assay has potential value as a screen for prostate cancer. Another acid phosphatase assay (RIA) proved difficult to perform for many institutions in the field trial. A new solid phase immunofluorescent assay recently introduced may on further testing be more sensitive than the CIEP assay. Total alkaline phosphatase levels studied in patients with advanced disease were markedly elevated in over one-third of the cases. Higher levels were associated with poor survival or response to chemotherapy. Alkaline phosphatase isozyme levels were of added value in locating the site of the increased alkaline phosphatase activity in soft tissue, bone, or liver. Occasionally in the face of a normal total value, increased isozyme activity in one of the aforementioned compartments preceded clinical ability to detect the metastatic foci.

Acid Phosphatase↗

PubMed2004

ACTH stimulates the release of alkaline phosphatase through Gi-mediated activation of a phospholipase C and the release of inositol-phosphoglycan.

We have previously reported that ACTH activates a phospholipase C that hydrolyzes glycosylphosphatidylinositol (GPI), which would release inositolphosphoglycan (IPG) to the extracellular medium, and that an IPG purified from Trypanosoma cruzi is able to inhibit ACTH-mediated steroid production in adrenocortical cells. In the present paper, it was found that anti-inositolphosphoglycan antibodies (anti-CRD) increased ACTH-mediated corticosterone production, which indicates that an endogenous IPG is a physiological inhibitor of ACTH response. On the other hand, we investigated the release to the extracellular medium of the GPI-anchored enzyme, alkaline phosphatase, by ACTH. We found that: (a) the released enzyme appeared in the aqueous phase after Triton X-114 partitioning, consistent with loss of the GPI, (b) the phospholipase C inhibitor, U73122, impaired the release of the enzyme by the hormone and (c) two inhibitors of IPG uptake, inositol 2-monophosphate and 2 M NaCl, increased the amount of alkaline phosphatase in the extracellular medium. These results suggest that ACTH releases alkaline phosphatase by activation of a phospholipase C. Dibutyryladenosine-3',5'-cyclic monophosphate (db-cAMP) was able to increase the release of alkaline phosphatase from adrenocortical cells and this effect was inhibited by U73122, suggesting that cAMP is involved in the activation of phospholipase C. In addition, it was found that a pertussis-toxin sensitive G-protein is required for ACTH- and db-cAMP-mediated release of alkaline phosphatase and that incorporation of anti-Gi antibodies in adrenocortical cells inhibited the release of alkaline phosphatase by ACTH. Our results suggest that ACTH increases the release of alkaline phosphatase by activation of a phospholipase C through cAMP and Gi which would contribute to produce IPG It was also found that the two inhibitors of IPG uptake, inositol-2-monophosphate and 2 M NaCl, increased the amount of alkaline phosphatase in the extracellular medium of ACTH-treated cells more than in control cells, indicating that ACTH also stimulates the uptake of IPG These data support a role of GPI and the involvement of Gi in ACTH action.

Adrenal Glands↗

PubMed1989

Localization of 1,25-(OH)2D3-responsive alkaline phosphatase in osteoblast-like cells (ROS 17/2.8, MG 63, and MC 3T3) and growth cartilage cells in culture.

Previous studies have shown 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3)-responsive alkaline phosphatase in cultured growth zone cartilage chondrocytes is localized in extracellular matrix vesicles (MV). Since osteoblast-like cells also have 1,25-(OH)2D3-responsive alkaline phosphatase, this study determined whether the 1,25-(OH)2D3-responsive enzyme activity is localized to MV produced by these cells as well. Osteoblast-like cells from rat (ROS 17/2.8), mouse (MC 3T3), human (MG 63), and rat growth zone cartilage were cultured in Dulbecco's modified Eagle's medium containing 10(-7)-10(-12) M 1,25-(OH)2D3. Alkaline phosphatase total activity and specific activity were measured in the cell layer, MV, and plasma membrane (PM) fractions. MV and PM purity were verified by electron microscopy and MV alkaline phosphatase specific activity compared to PM (MV versus PM: ROS 17/2.8 6 x; MG 63, 5.5 x; MC 3T3, 33 x; GC, 2 x). There was a dose-dependent stimulation of MV alkaline phosphatase (5- to 15-fold increase at 10(-7)-10(-9) M) in all cell types in response to the 1,25-(OH)2D3. The PM enzyme was stimulated in a parallel fashion in the osteoblast cultures. No effect of 1,25-(OH)2D3 was observed in growth cartilage PM. Although MV accounted for less than 20% of the total activity they contributed 50% of the increase in alkaline phosphatase activity in the cell layer in response to 1,25-(OH)2D3 and MV specific activity was enriched 10 times over that of the cell layer. These are common features of MV produced by cells which calcify their matrix and suggest that hormonal regulation of MV enzymes may be important in primary calcification.

Alkaline Phosphatase↗

PubMed1975

Serum alkaline phosphatase isoenzymes linked to immunoglobulin G.

An unusual isoenzyme pattern of serum alkaline phosphatase was found in a patient with skeletal abnormalities due to multiple epiphyseal dysplasia and it was demonstrated that the abnormal pattern was caused by complex formation between serum alkaline phosphatase and immunoglobulin G of the lambda class. Physicochemical studies of the patient's serum alkaline phosphatase showed the properties of an osseous enzyme. Evidence was obtained indicating that the complexing occurred in vitro and that the patient's immunoglobulin G had the ability to bind the hepatic and osseous isoenzymes selectively but not to bile, placental and intestinal isoenzymes. No abnormality was detected in the leucocyte isoenzyme pattern. The relationship between the occurrence of complex formation and the patient's bone disease was not established.

Alkaline Phosphatase↗

PubMed2005

Gene cloning, overproduction, and characterization of thermolabile alkaline phosphatase from a psychrotrophic bacterium.

The gene encoding alkaline phosphatase from the psychrotrophic bacterium Shewanella sp. SIB1 was cloned, sequenced, and overexpressed in Escherichia coli. The recombinant protein was purified and its enzymatic properties were compared with those of E. coli alkaline phosphatase (APase), which shows an amino acid sequence identity of 37%. The optimum temperature of SIB1 APase was 50 degrees C, lower than that of E. coli APase by 30 degrees C. The specific activity of SIB1 APase at 50 degrees C was 3.1 fold higher than that of E. coli APase at 80 degrees C. SIB1 APase lost activity with a half-life of 3.9 min at 70 degrees C, whereas E. coli APase lost activity with a half-life of >6 h even at 80 degrees C. Thus SIB1 APase is well adapted to low temperatures. Comparison of the amino acid sequences of SIB1 and E. coli APases suggests that decreases in electrostatic interactions and number of disulfide bonds are responsible for the cold-adaptation of SIB1 APase.

Alkaline Phosphatase↗

PubMed1990

Construction of a bifunctional Escherichia coli heat-stable enterotoxin (STb)-alkaline phosphatase fusion protein.

A fusion between the genes encoding the Escherichia coli STb heat-stable enterotoxin (estB) and alkaline phosphatase (phoA) was constructed, and the expressed protein product was characterized. The STb-alkaline phosphatase protein (STb-PhoA) had an apparent molecular mass of 50,000 daltons and was detected with both monoclonal anti-alkaline phosphatase and polyclonal anti-STb antibodies. Expression of the gene fusion resulted in high-level production of alkaline phosphatase activity, indicating that STb-PhoA was processed and exported into the periplasm of the E. coli host strain. Amino acid sequence analysis of the hybrid protein yielded the sequence Ser-Thr-Gln-Ser-Asn-Lys-Lys, indicating that STb-PhoA was processed during export in a fashion identical to that of native STb (Y. M. Kupersztoch, K. Tachias, C. R. Moomaw, L. A. Dreyfus, R. G. Urban, C. Slaughter, and S. Whipp, J. Bacteriol. 172: 2427-2432, 1990). STb-PhoA was purified from an expressed bacterial lysate by preparative isoelectric focusing. In a rat ligated intestinal loop model, purified STb-PhoA induced highly significant (P less than 0.002) fluid secretion. In addition, the specific activity of STb-PhoA was nearly identical to that of purified STb. Thus, the STb-PhoA hybrid protein represents a readily obtainable source of biologically active (STb) enterotoxin that may prove useful in studies to determine the mode of toxin action.

Alkaline Phosphatase↗

PubMed1989

Processing at the carboxyl terminus of nascent placental alkaline phosphatase in a cell-free system: evidence for specific cleavage of a signal peptide.

Alkaline phosphatase is anchored to the plasma membrane by a carboxyl-terminal phosphatidylinositol glycan moiety. To investigate the biosynthesis of mature alkaline phosphatase, nascent human placental alkaline phosphatase was expressed in a cell-free system and used as substrate for in vitro processing by microsomal extracts. By monitoring the processed product with three site-directed antibodies, it was shown that microsomal extracts from CHO cells that contain other recognized processing activities also remove the carboxyl-terminal signal peptide from the preproenzyme in an apparently selective manner. This peptidase-like cleavage may be brought about by the action of a specific transamidase acting on the nascent protein in the absence of an appropriate phosphatidylinositol glycan cosubstrate.

Alkaline Phosphatase↗

PubMedDate not supplied

Antigenic specificity of Escherichia coli alkaline phosphatase studied with monoclonal antibodies: immunological characterization of E. coli and Shigella strains.

Monoclonal antibodies (MoAb) to the alkaline phosphatase of Escherichia coli were produced from spleen cells of BALB/c mice primed with purified alkaline phosphatase of E. coli and SP2O/Ag-14 myeloma cells. Five stable clones were established. They all produced antibodies which reacted by enzyme-linked immunosorbent assay (ELISA) with alkaline phosphatase of all E. coli (25 strains) independently of their origin (drinking water, saline water, surface water, faecal or clinical origin), and with that of four Shigella species (7 strains) tested. Four of these MoAb gave a positive reaction with 52% (MoAb 4G10), 73% (MoAb 4F8, MoAb 4G6) and 89% (MoAb 3C8) of 14 other bacterial species (30 strains) studied, while one (MoAb 2E5) did not react with alkaline phosphatase of these unrelated bacterial strains and thus appeared specific for E. coli and Shigella species. This MoAb was still detectable in ascitic fluids at 1/500,000 in ELISA, and detected all E. coli strains in an indirect immunofluorescence assay at 1/100. It could therefore be used as a reagent for routine detection of E. coli in drinking water, foods or clinical specimens.

Alkaline Phosphatase↗

PubMed1998

Non-enzymatic glycosylation of alkaline phosphatase alters its biological properties.

Hyperglycaemia in poorly controlled diabetic patients induces non-enzymatic glycosylation (glycation) of proteins, altering their structure and physiological bioactivity. Alkaline phosphatase (ALP) is a membrane-bound exoenzyme which faces the extracellular compartment. We have investigated the glycation of intestinal alkaline phosphatase in vitro and the consequences of such molecular modifications on certain structural and functional characteristics. The effect of glycation on alkaline phosphatase specific activity was determined after incubation of the enzyme with different sugars for various periods of time. The formation of early reversible glycation products was determined by the measurement of fructosamine levels, while the appearance of advanced glycation end products was estimated by spectrofluorometric analysis. A decrease in the specific activity of ALP was associated both with an increase in fructosamine levels and with the appearance of AGE-characteristic fluorescence. Changes in these parameters were found to depend on the incubation time, and on the concentration and glycating capability of the sugar employed. Co-incubation with aminoguanidine slowed down the appearance of protein-linked fluorescence, and additionally curbed the decrease in enzymatic specific activity. A significant correlation between the levels of ALP-fructosamine and ALP-advanced glycation end product was observed. Patterns of protein bands fractionated by SDS-PAGE were essentially identical for the nonglycated controls and the glycated samples. The electrophoretic mobility of the band of alkaline phosphatase on cellulose acetate gels increased as a function of the incubation time and the glycosylating power of the carbohydrate used. The present study provides evidence for the in vitro glycation of alkaline phosphatase, and for the consecutive alteration of its activity and structure.

Alkaline Phosphatase↗

PubMed1974

Purification of human placental alkaline phosphatase. Salt effects in affinity chromatography.

Human placental alkaline phosphatase was chromatographed on Sepharose derivatives of d- and l-phenylalanine, l-leucine, glycine, aniline and p-aminobenzoic acid in high concentrations of (NH(4))(2)SO(4). Retention on these columns was greatest at the highest concentrations of (NH(4))(2)SO(4). By using decreasing concentrations and changing the types of salts, elution was effected from each of the columns. The (NH(4))(2)SO(4)-mediated retention appeared to be related to the hydrophobic character of the substituted Sepharose, rather than to any specific binding site of the enzyme. It is suggested that this provides a way of controlling hydrophobic affinity chromatography. By use of chromatography on l-phenylalanine-Sepharose and of DEAE-Sephadex chromatography in the presence of Triton X-100 detergent, a preparation of highly purified (1000-fold) human placental alkaline phosphatase was obtained in 22% yield.

Alkaline Phosphatase↗