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PubMed1981

Effect of fat feeding on intestinal alkaline phosphatase activity in tissue and serum.

Serum intestinal alkaline phosphatase activity is increased by fat feeding, but the mechanism of this increase is not fully understood. Fasting rats were fed a single feed of either corn oil (12 kcal) or an isocaloric elemental feed (Vivonex 100 HN). Changes in enzyme activity in the small bowel mucosa and serum were followed for 20 h. Only the fat-fed rats had increased serum enzyme activity, being maximal at 7 h and three times the fasting level. This resulted from an increase in the amount of enzyme protein in the serum and not from an increase in its catalytic efficiency. The serum biological half-life of 125I-labeled intestinal alkaline phosphatase was the same in fasted (2.51 min) and fat-fed rats (2.55 min). Both types of feed caused a quantitatively similar increase in brush-border-bound alkaline phosphatase activity. However, levels of soluble intracellular alkaline phosphatase in intestinal mucosa were affected differently: the elemental diet caused a substantial rise, whereas no significant change was seen after fat feeding. The isoelectric pattern of phosphatase activity in serum after fat feeding was identical to that of soluble intracellular and not membranous alkaline phosphatase. Therefore, serum intestinal alkaline phosphatase activity rises in response to a single fat feed as a result of increased delivery of the enzyme to the blood and not as a result of an increase in its normally short biological half-life. This rise cannot be directly linked to an increase in the amount of brush-border-bound enzyme, and it appears that the serum enzyme is derived directly from a pool of soluble intracellular enzyme in the small bowel mucosa.

Alkaline Phosphatase↗
PubMed1995

The cyanobacterium Synechococcus sp. strain PCC 7942 contains a second alkaline phosphatase encoded by phoV.

A gene (phoV) encoding an alkaline phosphatase from Synechococcus sp. strain PCC 7942 was isolated by screening a plasmid gene bank for expression of alkaline phosphatase activity in Escherichia coli JM103. Two independent clones carrying the same alkaline-phosphatase-encoding gene were isolated. One of these clones (pKW1) was further analysed and the nucleotide sequence of a contiguous 3234 bp DNA fragment was determined. Two complete open reading frames (ORF1 and phoV) and an incomplete ORF3 were identified reading in the same direction. The deduced phoV gene product showed 34% identity to the alkaline phosphatase PhoA from Zymomonas mobilis, and the N-terminal part of the putative ORF3 protein exhibited 57% identity to a protein of unknown function from Frankia sp. Insertional inactivation of the Synechococcus PCC 7942 phoV gene failed, indicating an essential role for either the phoV or the ORF3 gene product. PhoV consists of 550 amino acid residues, resulting in a molecular mass of 61.3 kDa. To overexpress the Synechococcus PCC 7942 phoV gene in E. coli, plasmid pKW1 was transformed into a phoA mutant of E. coli (CC118). In E. coli strain CC118(pKW1) PhoV was expressed constitutively with high rates of activity, and was shown to be membrane associated in the periplasmic space. After partial purification of the recombinant PhoV, it was shown that, like other alkaline phosphatases, the Synechococcus PhoV had a broad pH optimum in the alkaline region and a broad substrate specificity for phosphomonoesters, required Zn2+ for activity, and was inhibited by phosphate. In contrast to several other alkaline phosphatases, PhoV was inhibited by Mn2+. Due to the lack of a Synechococcus PCC 7942 phoV mutant strain, the function of PhoV remains uncertain. However, the present results show that Synechococcus PCC 7942 has a second, probably phosphate-irrepressible, alkaline phosphatase (PhoV, 61.3 kDa) in addition to the phosphate-repressible enzyme (PhoA, 145 kDa) already described.

Alkaline Phosphatase↗
PubMed1971

Influence of the indigenous gastrointestinal microbial flora on duodenal alkaline phosphatase activity in mice.

Alkaline phosphatase activity was assayed by two procedures in duodenal homogenates from specific pathogen-free (SPF) mice of various ages, adult germfree mice, adult ex-germ-free mice colonized with an indigenous microflora from the SPF mice, and adult ex-germ-free mice monocontaminated with a Lactobacillus sp. indigenous to the SPF mice. In the SPF neonates, the activity remained at low levels until at least 12 days of age, increased to high levels at 20 days of age, and then fell to adult levels between the early neonatal and later high levels. In the germ-free mice, the activity levels were significantly higher than the levels in SPF mice at any age. In contrast, in the ex-germ-free animals, colonized by an entire indigenous microflora, the values fell within the range for adult SPF animals. In the ex-germ-free mice colonized only by the Lactobacillus sp., the activity levels were intermediate between the values for germ-free and SPF mice. These findings show that the indigenous microbial flora influences considerably the intestinal alkaline phosphatase activity in the mouse.

Journal Article↗
PubMed2002

Intestinal alkaline phosphatase release is not associated with chylomicron formation.

Intestinal alkaline phosphatase (IAP) is one of the major sources of alkaline phosphatase in circulation. It is secreted into the intestinal lumen, serum, and lymph. After the ingestion of lipid, lymphatic alkaline phosphatase secretion increases significantly. We have found that the nonabsorbable fat olestra is unable to stimulate lymphatic alkaline phosphatase secretion. We also found that the hydrophobic surfactant Pluronic L-81, which blocks chylomicron formation, fails to inhibit this increase in lymphatic alkaline phosphatase secretion. These results suggest that it is the lipid uptake into the mucosa and/or reesterification to form triacylglycerols, but not the formation of chylomicrons, that is necessary for the stimulation of the secretion of alkaline phosphatase into the lymph.

Alkaline Phosphatase↗
PubMed1984

Placental alkaline phosphatase in tumour tissue and serum.

Using immunochemical techniques, alkaline phosphatase isoenzymes were determined in tissue samples of breast carcinomas and carcinomas of the gastrointestinal tract. In breast carcinomas only 19% of the patients expressed significant placental alkaline phosphatase activity, compared with 78% in gastrointestinal tumours. The intestinal isoenzyme was found in 50% of the breast carcinomas and in nearly all of the other examined tissues. The two isoenzymes usually represent 1% of the total alkaline phosphatase activity, but in a few cases they may constitute between 10 and 90%. In the serum of the patients under examination, elevated total alkaline phosphatase activity was found in only 7%, and elevated placental alkaline phosphatase in 6% of the cases. No cases of elevated serum intestinal alkaline phosphatase were found. We therefore consider that serum placental alkaline phosphatase is a poor tumour marker for a general screening.

Alkaline Phosphatase↗
PubMed1984

Chloride binding to alkaline phosphatase. 113Cd and 35Cl NMR.

Chloride binding to alkaline phosphatase from Escherichia coli has been monitored by 35Cl NMR for the native zinc enzyme and by 113Cd NMR for two Cd(II)-substituted species, phosphorylated Cd(II)6 alkaline phosphatase and unphosphorylated Cd(II)2 alkaline phosphatase. Of the three metal binding sites per enzyme monomer, A, B, and C, only the NMR signal of 113Cd(II) at the A sites shows sensitivity to the presence of Cl-, suggesting that Cl- coordination occurs at the A site metal ion. From the differences in the chemical shift changes produced in the A site 113Cd resonance for the covalent (E-P) form of the enzyme versus the noncovalent (E . P) form of the enzyme, it is concluded that the A site metal ion can assume a five-coordinate form. The E-P form of the enzyme has three histidyl nitrogens as ligands from the protein to the A site metal ion plus either two water molecules or two Cl- ions as additional monodentate ligands. In the E . P form, there is a phosphate oxygen as a monodentate ligand and either a water molecule or a Cl- ion as the additional monodentate ligand. The shifts of the 113Cd NMR signals of the unphosphorylated Cd(II)2 enzyme induced by Cl- are very similar to those induced in the E-P derivative of the same enzyme, supporting the conclusion that the phosphoseryl residue is not directly coordinated to any of the metal ions. Specific broadening of the 35Cl resonance from bulk Cl- is induced by Zn(II)4 alkaline phosphatase, while Zn(II)2 alkaline phosphatase is even more effective, suggesting an influence by occupancy of the B site on the interaction of monodentate ligands at the A site. A reduction in this quadrupolar broadening is observed upon phosphate binding at pH values where E . P is formed, but not at pH values where E-P is the major species, confirming a specific interaction of Cl- at the A site, the site to which phosphate is bound in E . P, but not in E-P. For the zinc enzyme, a significant decrease in phosphate binding affinity can be shown to occur at pH 8 where one monomer has a higher affinity than the other.

Alkaline Phosphatase↗
PubMed1981

Improved method for quantitative determination in serum of alkaline phosphatase of skeletal origin.

In this quantitative method for detection of skeletal alkaline phosphatase (EC 3.1.3.1) activity in human serum, intestinal and placental alkaline phosphatase activities are recognized by their susceptibility to inhibition by L-phenylalanine, and skeletal and hepatic alkaline phosphatases are distinguished by their different sensitivities to inactivation by heat. Alkaline phosphatase isoenzymes prepared from organ sources may behave differently from the corresponding isoenzymes in serum. Our procedure allows us to include organ-derived internal standards of skeletal, intestinal, and biliary alkaline phosphatase to minimize between-assay variation. In preliminary applications, we have found that (a) total serum alkaline phosphatase activity is extremely variable in post-menopausal osteoporotic subjects and is not a reliable index of skeletal alkaline phosphatase activity; (b) seven osteoporotic patients responding to therapy with sodium fluoride with increased bone formation showed increased skeletal alkaline phosphatase activity in their serum as compared with age-matched controls (p less than 0.005); and (c) 10 post-menopausal osteoporotic patients responding to therapy with stanozolol with increased total body calcium showed an increase in circulating skeletal alkaline phosphatase activity (p less than 0.001).

Alkaline Phosphatase↗
PubMed1985

Effect of elastase on the histochemical demonstration of alkaline phosphatase activity in chick pecten.

The effect of elastase on alkaline phosphatase activity in the chick pecten capillaries was studied electron histochemically. The pecten was treated with elastase before incubation in the medium for alkaline phosphatase. Inactive alkaline phosphatase in the chick pecten capillary under dark adaptation could be demonstrated electron histochemically after treatment with elastase. Under light adaptation, the elastase-treated pecten demonstrated more intense alkaline phosphatase activity in the same localization as in the untreated pecten. Biochemical data also supported histochemically demonstrated enhancement effect of elastase on alkaline phosphatase activity in the chick pecten oculi. Elastase is expected to be useful for demonstrating enzymatic activity which is otherwise hard to detect.

Adaptation, Physiological↗
PubMed1980

Distribution of acid and alkaline phosphatase in buffalo spermatozoa.

The distribution of acid phosphatase (EC 3.1.3.1) and alkaline phosphatase (EC 3.1.3.2) was studied in the head, midpiece and tail fractions of buffalo spermatozoa. Fractionation was achieved by the basic principles of ultrasonication and density gradient centrifugation. The activity of acid phosphatase in the head, midpiece and tail fractions was 7.30, 11.55 and 47.10 and for alkaline phosphatase 1.74, 6.95 and 26.71 respectively; the unit being microgram of inorganic phosphorus liberated/mg of protein/h at 37 degrees C.

Acid Phosphatase↗
PubMed1983

Determinants of variation in plasma alkaline phosphatase activity: a twin study.

Plasma alkaline phosphatase activity has been measured in 204 pairs of twins aged 18-34. Estimated genetic variance was the same in men and women, after exclusion of the youngest men, but environmental variance was greater in men so that the heritability was .90 +/- .02 in the women and .71 +/- .05 in the 19-34-year-old men. About 15% of the genetic variance was associated with the ABO blood group polymorphism, which is known to affect intestinal alkaline phosphatase. Differences in plasma alkaline phosphatase activity between normal people may be mainly due to genetically determined proportions of isoenzymes of differing stability.

ABO Blood-Group System↗
PubMed1977

Comparison of the inhibition of avian and mammalian bone alkaline phosphatases by levamisole and compound R8231.

Alkaline phosphatases from mammalian bone are inhibited much more than chick bone alkaline phsophatase by levamisole and compound R8231. Doses of R8231 (10(-4) to 10(-5) M) that almost completely inhibit mammalian alkaline phosphatases do not inhibit the growth of embryonic rat femurs in vitro. R8231 should be an excellent biological probe for the function of alkaline phosphatase in bone metabolism.

Alkaline Phosphatase↗
PubMed1980

Placental alkaline phosphatase in nonmalignant human cervix.

At least three loci determine human alkaline phosphatases [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1]: one coding for the placental form of the enzyme; at least one coding for the intestinal forms; and at least one for the liver, bone, and kidney forms. It is generally believed that the locus determining the placental form is, in the normal individual, expressed only in placenta. However, ectopic or aberrant expression of this locus occurs in certain malignancies of other tissues and in cell lines, such as HeLa, derived from malignancies. We have examined by thermostability, inhibition, and immunologic studies the alkaline phosphatases in endocervix, cervical mucus, and endometrium from nonpregnant women with no evidence of malignancy. It was found that on the average about 18% of the alkaline phosphatase activity in endocervix and in cervical mucus is placental in type, the remainder being of the liver/bone/kidney type. The quantity of the placental enzyme is, however, low and amounts to only about 0.5% of the amount in normal term placenta. In endometrium all the alkaline phosphatase activity was of the liver/bone/kidney type. Thus the placental alkaline phosphatase locus is expressed in nonmalignant endocervix. The result is of some significance in connection with the widely held view that the expression of placental alkaline phosphatase in certain malignancies (including cervical malignancy) is due to derepression of a locus for a fetal enzyme protein normally repressed in adult tissues.

Adult↗
PubMed1986

Origin of alkaline phosphatase of canine seminal plasma.

The tissular origin of alkaline phosphatase was evaluated in canine seminal plasma. Alkaline phosphatase activity was most concentrated in the first fraction of the split ejaculate and was virtually undetectable in the third and fourth fractions. By contrast, arginine esterase, a known marker of dog prostatic secretion, was present in similar concentrations in all fractions of the split ejaculates analyzed by SDS gel electrophoresis. Similarly, arginine esterase was very abundant in secretory granules prepared from dog prostate homogenates, whereas these granules contained virtually no alkaline phosphatase. Among male sex accessory organs, alkaline phosphatase activity was very high in the epididymis and much lower in the testis and prostate. Furthermore, the specific activity in epididymal fluid collected from the cauda epididymis was about 10 times higher than in the corresponding epididymal homogenates. These results show that the major portion of alkaline phosphatase in dog seminal plasma does not come from the prostate but from the epididymis.

Alkaline Phosphatase↗
PubMed1981

Inhibition of alkaline phosphatase by bismuth.

The interaction of alkaline phosphatase (EC 3.1.3.1) with bismuth was studied. Among the tested alkaline phosphatases, bismuth was found to be the most effective inhibitor of the placental enzyme. Partial denaturation of the placental enzyme by papain digestion had little effect, if any, on the inhibition. Bismuth inhibition of the placental enzyme activity was more progressive with mixed glycosidase treatment than with sialidase treatment. The pH activity profile of the mixed glycosidase-treated placental enzyme was clearly shifted in the presence of bismuth. The mixed glycosidase-treated placental enzyme/bismuth mixture was more heat labile than the non-treated placental enzyme. Based on the results of kinetic studies, the inhibition mechanism of the placental enzyme by bismuth was shown to be of the competitive type, and the Ki value and Hill coefficient of the mixed glycosidase-treated placental enzyme was found to be 92 mu mol/l and 2.25, respectively. L-Phenylalanine does not interfere with the inhibitory effect of bismuth on alkaline phosphatase. Inorganic phosphate, on the other hand, appears to disturb bismuth bindings.

Alkaline Phosphatase↗
PubMed1987

[In vivo inhibition by ethyloxanilates of alkaline phosphatases of the cestode Echinococcus multilocularis].

Alkaline phosphatases (E.C.3.1.3.1), membranous enzymes of the cestode Echinococcus multilocularis have been studied in the parasite and in the experimental host liver. Synthetic inhibitors interaction with metacestode alkaline phosphatases is reported. In regard to the alkaline phosphatases inhibition, the ethyloxanilate 2 is more efficient in the cestode itself than in the host liver.

Alkaline Phosphatase↗
PubMed1969

Serum alkaline phosphatase in adult coeliac disease.

The total alkaline phosphatase levels were determined in 118 patients with adult coeliac disease, 65 of whom had evidence of osteomalacia.The secretor and blood group status, intestinal isoenzyme, and liver alkaline phosphatase played no significant part in the levels of serum alkaline phosphatase found. There was a significant correlation between the levels of serum alkaline phosphatase and the presence of osteomalacia.

ABO Blood-Group System↗
PubMed1983

Pyridoxal 5'-phosphate disappearance from perfused rat jejunal segments: correlation with perfusate alkaline phosphatase and water absorption.

The relative effects of perfusate alkaline phosphatase activity and net water absorption on 2 microM pyridoxal 5'-phosphate (PLP) luminal disappearance from rat jejunum were studied in a single-pass, in vivo perfused intestinal segment model. Perfusate consisted of unlabeled PLP in buffer (pH = 7.4). Net water flux was monitored by inclusion of [3H]polyethylene glycol. PLP was measured by the [14C]tyrosine apodecarboxylase assay. Single and multiple regression analysis of results during perfusion of 2 microM PLP in Krebs bicarbonate buffer demonstrated no correlation between perfusate alkaline phosphatase activity and net water absorption and significant correlations between PLP luminal disappearance and both perfusate alkaline phosphatase activity and net water absorption. Correlation for the latter was improved when disappearance results were corrected for variations in perfusate alkaline phosphatase activity. When perfusate buffers were selected to yield divergent rates of net water absorption, the one associated with greater net water absorption was also associated with greater PLP disappearance. That this could not be explained by changes in perfusate alkaline phosphatase activity was demonstrated both by assessment of the rate of decay of PLP added in vitro to exited perfusate incubated at 37 degrees C and by measurement of alkaline phosphatase activity under conditions defined by the buffers using a modified spectrophotometric assay. Conclusions were: (1) In vivo PLP luminal disappearance correlates significantly with both perfusate alkaline phosphatase activity and net water absorption; (2) these two factors appear to act as independent variables; and (3) future studies on PLP intestinal absorption will need to take both of these variables into account in the interpretation of results.

Alkaline Phosphatase↗