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A novel alkaline phosphatase, a minor component of normal liver phosphatases.

A novel alkaline phosphatase differing from the so-called liver-specific isoenzyme was found in four out of twenty-four normal adult livers. Although the mobility of this enzyme was the same as that of so-called liver-specific alkaline phosphatase on the polyacrylamide gel electrophoretogram, its mobility was not altered following neuraminidase treatment, while that of the liver-specific enzyme was affected by the same treatment. Both enzymes also differed in other enzymatic and immunologic properties. The enzyme, however, resembled the so-called intestinal alkaline phosphatase in many enzymatic and immunologic properties. Thus, the inhibition patterns by amino acids, EDTA and inorganic phosphate, the pH optima, KM values for phenyl phosphate and reactivity with anti-intestinal alkaline phosphatase antibody were quite similar for both enzymes. Differences in the properties of this enzyme and intestinal alkaline phosphatase were in sensitivity to denaturation by treatment with heat and urea and to inhibition by Levamisole. The possible origin of the enzyme in normal liver and its relationship to the Kasahara isoenzyme and fetal intestine-type in hepatoma is discussed.

Adult↗

Influence of certain indigenous gastrointestinal microorganisms on duodenal alkaline phosphatase in mice.

Alkaline phosphatase activity was assayed in duodenal homogenates or extracts from adult specific pathogen-free (SPF) and germfree mice and gnotobiotic mice monoassociated with a Lactobacillus sp., a Bacteroides sp., or a coliform strain indigenous to SPF mice. Activity levels of the enzyme were much higher in the preparations from germfree mice than in those from the SPF controls. In the gnotobiotes monoassociated either with a freshly isolated Lactobacillus sp. or a Bacteroides sp., the levels of alkaline phosphatase activity were intermediate between the values for germfree and SPF mice. By contrast, in the gnotobiotes monoassociated with a coliform strain, alkaline phosphatase activity remained at high germfree levels. Butanol extracts of duodenal tissue from SPF mice, germfree mice, and exgermfree mice associated with an indigenous microflora from SPF mice (conventionalized) were subjected to acrylamide gel electrophoresis. A stain for alkaline phosphatase activity revealed three major bands in the gels prepared with extracts from SPF and conventionalized mice, but only two in the gels prepared with extracts from germfree mice. All three bands may have been present in the latter gels. One of the bands (the middle one) may have been obscured, however, by high activity in the slowest moving band. As determined by densitometric scanning, the slowest moving band had much higher activity in the preparations from germfree animals than in those from SPF or conventionalized mice. These findings suggest that the indigenous microbial flora affects not only quantitatively, but also qualitatively, the activity of alkaline phosphatases in the mouse intestinal mucosa.

Alkaline Phosphatase↗

Use of specific inhibitors to disciminate alkaline phosphatase isoenzymes originating from human liver, placenta and intestine: absence of meconial alkaline phosphatase in maternal serum.

We used the inhibitors bromotetramisole, L-phenylalanine amide, and L-phenylalanine in combination to measure intestinal phosphatase in maternal serum and amniotic fluid. By using high concentrations of these inhibitors, it was possible to measure the three isoenzymes separately. We found no evidence of the presence of meconial alkaline phosphatase in the serum of the mother (six cases) after meconial passage in utero.

Alkaline Phosphatase↗

Diagnostic value of determination of acid and alkaline phosphatase levels in the seminal plasma of infertile males.

To investigate the diagnostic value of phosphatases in seminal plasma, the levels of acid phosphatase and alkaline phosphatase were determined in 15 fertile subjects as well as in 26 cases of oligoasthenozoospermia. Statistical analysis of obtained data showed that acid phosphatase is a reliable parameter of prostatic function in cases of infection, while alkaline phosphatase may prove to be a non-specific parameter of subfertile semen. Alkaline phosphatase was significantly diminished in both oligozoospermia and azoospermia with and without infection or varicocele.

Acid Phosphatase↗

Phosphate binding in the active site of alkaline phosphatase and the interactions of 2-nitrosoacetophenone with alkaline phosphatase-induced small structural changes.

To monitor structural changes during the binding of Pi to the active site of mammalian alkaline phosphatase in water medium, reaction-induced infrared spectroscopy was used. The interaction of Pi with alkaline phosphatase was triggered by a photorelease of ATP from the inactive P(3)-[1-(2-nitrophenyl)]ethyl ester of ATP. After photorelease, ATP was sequentially hydrolyzed by alkaline phosphatase giving rise to adenosine and three Pi. Although a phosphodiesterase activity was detected prior the photorelease of ATP, it was possible to monitor the structural effects induced by Pi binding to alkaline phosphatase. Interactions of Pi with alkaline phosphatase were evidenced by weak infrared changes around 1631 and at 1639 cm(-1), suggesting a small distortion of peptide carbonyl backbone. This result indicates that the motion required for the formation of the enzyme-phosphate complex is minimal on the part of alkaline phosphatase, consistent with alkaline phosphatase being an almost perfect enzyme. Photoproduct 2-nitrosoacetophenone may bind to alkaline phosphatase in a site other than the active site of bovine intestinal alkaline phosphatase and than the uncompetitive binding site of L-Phe in bovine intestinal alkaline phosphatase, affecting one-two amino acid residues.

Adenosine Triphosphate↗

Asparagine-linked carbohydrate does not determine the cellular location of yeast vacuolar nonspecific alkaline phosphatase.

The nonspecific alkaline phosphatase of Saccharomyces sp. strain 1710 has been shown by phosphatase cytochemistry to be exclusively located in the vacuole, para-Nitrophenyl phosphate-specific alkaline phosphatase is not detected by this procedure because the activity of this enzyme is sensitive to the fixative agent, glutaraldehyde. To determine whether the oligosaccharide of nonspecific alkaline phosphatase is necessary to transport the enzyme into the vacuole, protoplasts were derepressed in the absence or in the presence of tunicamycin, an antibiotic which interferes with the glycosylation of asparagine residues in proteins. The location of the enzyme in the tunicamycin-treated protoplasts, as determined by electron microscopy and subcellular fractionation, was identical to its location in control protoplasts. In addition, carbohydrate-free alkaline phosphatase was found in vacuoles from tunicamycin-treated protoplasts. Our findings indicate that the asparagine-linked carbohydrate moiety does not determine the cellular location of the enzyme.

Alkaline Phosphatase↗

Paradoxical effects of phosphate to directly regulate the level of skeletal alkaline phosphatase activity in human osteosarcoma (SaOS-2) cells and inversely regulate the level of skeletal alkaline phosphatase mRNA.

Recent studies indicate that the amount of alkaline phosphatase (ALP) activity in human osteoblast-line cells is proportional to the concentration of phosphate in the culture medium. The current studies were intended to extend those observations and to determine whether the effects of phosphate (and phosphate esters and analogs) to alter the cellular level of ALP activity, in human osteosarcoma SaOS-2 cells, reflected regulation at the level of transcription. Consistent with previous findings, we found direct, time- and dose-dependent correlations between the concentration of phosphate and the amount of ALP activity/mg cell protein (P < 0.05). Surprisingly, we also found a negative correlation between the phosphate concentration in the medium and the level of skeletal ALP mRNA (e.g., r = -0.98, P < 0.01 at 24 hours). As the highest cellular levels of skeletal ALP activity were associated with the lowest levels of ALP mRNA, these data indicated that the phosphate-dependent increase in ALP activity was not mediated by an increase in transcription and, conversely, that the effect of phosphate withdrawal to decrease ALP activity was not mediated by a decrease in transcription.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗

Histochemical and electrophoretical studies in normal and infected Biomphalaria glabrata. II. Acid and alkaline phosphatase.

Various organs of normal and infected Biomphalaria glabrata were analysed, electrophoretically and histochemically, with respect to the acid phosphatase and alkaline phosphatase activity. In general, digestive gland, ovotestis and stomach show an increase in acid phosphatase activity in infected snails, whereas kidney and albumen gland show less activity. Alkaline phosphatase does not show any significant different in activity between normal and infected snails. Electrophoretically digestive glands of snails, twenty days after infection, show an extra faint band, whereas seven days after infection, the snails do not show any such extra band. Histochemically also after twenty days, infected snails show more activity in the sporocyst region, but those infected for only seven days, do not show any increase in acid phosphatase activity.

Acid Phosphatase↗

Effect of synthetic human parathyroid hormone on the levels of alkaline phosphatase activity and formation of alkaline phosphatase-rich matrix vesicles by primary cultures of chicken epiphyseal growth plate chondrocytes.

The effect of synthetic human parathyroid hormone (hPTH) on the formation of matrix vesicles (MV), and on the rate of cell division, production of cellular alkaline phosphatase (AP) and protein by primary cultures of chicken epiphyseal growth plate hypertrophic chondrocytes was investigated. Addition to serum-containing or serum-free media of physiological levels of hPTH, in a range from 0.1 to 10 nM, caused a progressive decrease in the formation of AP-rich MV. However, studies on incorporation of [3H]choline into MV indicate that MV formation per se was not significantly decreased. hPTH was found to markedly decrease the expression of cellular AP, accompanied by an increase in cell division [( 3H]thymidine incorporation) and protein synthesis. Since these effects of hPTH were augmented by 3-isobutyl-1-methylxanthine (IBMX), a phosphodiesterase inhibitor, and mimicked by the cAMP analogue N6,O2'-dibutyryl-adenosine 3',5'-cyclic-monophosphate (DBcAMP), the findings clearly indicate that hPTH was acting through the classic cAMP-mediated mechanism. Inasmuch as elevation of AP in growth plate chondrocytes coincides with MV formation, maturation and hypertrophy of the cells, and induction of mineralization, the stimulation of cell division and suppression of cellular AP indicates that hPTH would cause the cells to revert to a less differentiated state. Thus, elevation in PTH, which results from lowered circulating levels of Ca2+, should inhibit mineral deposition in the growth plate. This may be a physiological protective mechanism to prevent a further drain on serum Ca2+.

1-Methyl-3-isobutylxanthine↗

Allotype immunoglobulin enhances alkaline phosphatase activity: implications for the inflammatory response.

To understand the interactions among components of the immune/inflammation response, we studied the effects of immunoglobulins on the phosphatase activity of alkaline phosphatase in vitro. Bovine intestinal alkaline phosphatase was incubated with substrate in the presence of allotypic and xenotypic immunoglobulin. We found that bovine but not rabbit immunoglobulin enhanced the phosphatase activity of bovine intestinal alkaline phosphatase. Similarly, human but not bovine immunoglobulin G enhanced human placental alkaline phosphatase activity. By enhancing alkaline phosphatase activity, immunoglobulins bound to alkaline phosphatase may assist physiologic transport functions and enhance resolution of the inflammatory response. Further, in clinical conditions with high immunoglobulin concentrations, the serum alkaline phosphatase recorded may have spuriously high values.

Alkaline Phosphatase↗