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PubMed1976

Characterization of KB cell alkaline phosphatase. Evidence of similarity to placental alkaline phosphatase.

The alkaline phosphatase from KB cells was purified, characterized, and compared to placental alkaline phosphatase, which it resembles immunologically. Two nonidentical nonomeric subunits of the KB phosphatase were found. The two subunits, which have apparent molecular weights of 64,000 and 72,000, can be separated on polyacrylamide gels containing sodium dodecyl sulfate. The Mr = 64,000 KB subunit appears to be identical in protein structure to the monomer of placental alkaline phosphatase. The Mr = 72,000 KB subunit, while differing in the NH2-terminal amino acid, appears also to be very similar to the placental alkaline phosphatase monomer. Both KB phosphatase subunits bind (32P)phosphate, and bind to Sepharose-bound anti-placental alkaline phosphatase. Native KB phosphatase is identical to the placental isozyme in isoelectric point, pH optimum, and inhibition by amino acids, and has a very similar peptide map. The data presented support the hypothesis that the Mr = 64,000 KB phosphatase subunit may the the same gene product as the monomer of placental alkaline phosphatase. This paper strengthens the evidence that the gene for this fetal protein, normally repressed in all cells but placenta, is derepressed in the KB cell line. In addition, this paper presents the first structural evidence that there are two different subunit proteins comprising the placental-like alkaline phosphatase from a human tumor cell line.

Alkaline Phosphatase↗
PubMed1981

Electrophoretic separation of alkaline phosphatase isoenzymes compared with alkaline phosphatase and gamma-glutamyltransferase in hepatobiliary diseases.

Electrophoretic separation of serum alkaline phosphatase fractions and measurement of serum alkaline phosphatase and serum gamma-glutamyltransferase were carried out in 82 consecutive patients with suspected hepatobiliary disease to investigate the usefulness of the three tests in distinguishing between parenchymatous hepatic disease and occlusive hepatobiliary disease. It was concluded that measurement of total serum alkaline phosphatase was superior to the two other tests.

Alkaline Phosphatase↗
PubMed1992

Interphotoreceptor retinoid binding protein induced experimental autoimmune uveitis: an immunophenotypic analysis using alkaline phosphatase anti-alkaline phosphatase staining, dual immunofluorescence and confocal microscopy.

Using a Lewis rat model of IRBP induced EAU, we have examined the progress of leucocytes infiltrating the uveitic eye. APAAP and dual immunofluorescence were used to show that ED7 and 8 (CD11b/CD18) positive monocytes, W3/25 and OX8 (CD4 and CD8) lymphocytes were prominent in the initial inflammatory exudate around the retinal vessels and in the choroid. ED1 positive monocytes were also observed in the choroid. As disease progressed, these cells moved into the inner retina, vitreous and ROS. ED8 positive cells were the first to appear in the ROS. This was followed by the later appearance of ED2 tissue macrophages in the vitreous and ED3 inflammatory macrophages in the vitreous and ROS.

Alkaline Phosphatase↗
PubMed2001

Quantitation of soluble and skeletal alkaline phosphatase, and insoluble alkaline phosphatase anchor-hydrolase activities in human serum.

BACKGROUND: The current studies were intended to compare the circulating levels of total and anchorless (soluble) skeletal and hepatic ALP isoenzyme activities, and insoluble ALP anchor-hydrolase activity in serum of postmenopausal women. METHODS: Preliminary studies of the insoluble ALP anchor-hydrolase activity in serum revealed a pH optimum of pH 5-6.5, a sensitivity to inactivation by heat at temperatures >45 degrees C (t(1/2)=8-9 min at 60 degrees C), and an apparent K(M) (at pH 7.5) of 40-45 mU/ml of insoluble skeletal ALP activity. RESULTS: Serum analyses showed that 94.5+/-0.5% (mean+/-SEM) of the ALP activity in serum was in the anchorless, soluble form. The data were also consistent with the notion that the amount of insoluble ALP anchor-hydrolase activity in serum, 52.8+/-0.8 U/l (mean+/-SEM), was sufficient for the conversion of anchor-intact (insoluble) ALP into the anchorless, soluble form, assuming activation by serum lipids and/or bile salts. Distributions of results for total, skeletal, hepatic, and insoluble ALP anchor-hydrolase activity were skewed toward the higher range and leptokurtotic (p<0.01 for each). Total ALP activity ranged from 42% to 208% of the group mean value; skeletal, hepatic, and insoluble ALP anchor-hydrolase activities ranged from 5% to 306%, 33% to 277%, and 2% to 325%, respectively. In contrast, the soluble ALP fraction only ranged from 71% to 106% of the group mean value. CONCLUSIONS: The correlations between the total and both skeletal (r=0.711, p<0.001) and hepatic (r=0.782, p<0.001) ALP isoform activities were predictive. Although correlations were also observed between insoluble ALP anchor-hydrolase activity and total (r=0.197, p<0.001), hepatic (r=0.184, p<0.001) and skeletal ALP activities (r=0.118, p<0.05), those relationships were not predictive (r(2)<0.04).

Alkaline Phosphatase↗
PubMed1975

Correlation between serum alkaline phosphatase and localization of alkaline phosphatase in the liver.

1. A good correlation exists between histochemically judged and biochemically determined activity of alkaline phosphatase in the liver. 2. Normal localization of alkaline phosphatase in the human differs from that in the rat. 3. In Wistar rats normal localization is: low or no activity in bile canaliculi preferently in the peripheral part of the lobule. 4. Normal localization in the human is: moderate to strong activity in the sinusoidal wall, in the central and peripheral part of the lobule. 5. A relation exists between histochemical localization and serum value of alkaline phosphatase in rat and in human. 6. Raised activities at localizations where "normally" no activity is present, e. g. bile canaliculi in human, sinusoidal wall in rat, do correlate the best with raised serum activities.

Alkaline Phosphatase↗
PubMed1995

Amino acid phosphatase activity of alkaline phosphatase. A possible role of protein phosphatase.

Alkaline phosphatase (ALP) hydrolyzed phosvitin and amino acid phosphates demonstrating nonisotropy at different pH. Orthovanadate, a protein phosphatase inhibitor, more specifically inhibited the serine and tyrosine phosphatase activities of ALP than that of threonine phosphatase at concentrations > 0.1 mM or 0.01 mM, respectively. Calyculin A and okadaic acid at increased concentrations increased ALP amino acid phosphatase activity. Bisphosphonates, such as disodium-1-hydroxy-1-aminopropylidine-1,1-diphosphonate (APD) and ethane-1-hydroxy-1,1-diphosphonate (HEBP), at increased concentrations, inhibited ALP amino acid phosphatase activity. These results suggest that ALP may function as a protein phosphatase. In terms of protein kinase inhibitors, N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide, N-(6-aminoheyxl)-5-chloro-1-naphthalenesulfomide hydrochloride and 4',5,7-trihydroxyisoflavone had little effect on ALP amino acid phosphatase activity. Staurosporine slightly enhanced ALP serine and threonine phosphatase activities at a concentration of 0.1 mM. These results suggest that protein phosphatase activity does not depend on the protein kinase activity of ALP, since duality between the former and the latter is not supported. ALP may function less as a protein kinase than as a protein phosphatase. The coupling mechanism of phosphate dynamics may be regulated indirectly.

Alkaline Phosphatase↗
PubMed2002

The effect of different buffers and amounts of intestinal alkaline phosphatase isoforms on total alkaline phosphatase activity.

BACKGROUND: The transphosphorylating accepter buffers (2-amino-2-methyl-1-propanol, AMP; N-methyl-D-glucamine, MEG; diethanolamine, DEA and 2-ethylaminoethanol, EAE) have been widely used for the measurement of serum total alkaline phosphatase activity (ALP) in clinical laboratories, and the individual isozyme are activated differently by respective buffers. MATERIALS AND METHODS: We examined the activity of serum ALP using four buffers with levels of both high molecular weight intestinal alkaline phosphatase (HIAP) and normal molecular weight intestinal alkaline phosphatase (NIAP). We classified 80 healthy subjects into two groups of blood group B or O secretors (n=36) and other blood groups (n=44). RESULTS: The mean ALP activities at fasting in blood group B or O secretors from AMP, MEG, DEA and EAE methods were 15.5%, 24.0%, 11.0% and 22.1% higher than those in other blood groups, respectively. The reference ranges of ALP activity at fasting with the AMP method in blood group B or O secretors and other blood groups were 63.5+/-17.4 U/l (mean+/-S.D.) and 55.0+/-14.5 U/l (mean+/-S.D.), respectively. The difference between the reference ranges of ALP activity in blood group B or O secretors and other blood groups was statistically significant (p<0.01). HIAP and NIAP in serum at fasting only appeared in blood group B or O secretors, and the activities of HIAP and NIAP were 4.7+/-3.4 U/l (mean+/-S.D.) and 2.2+/-1.2 U/l (mean+/-S.D.), respectively. The activity of ALP-(HIAP+NIAP) in blood group B or O secretors was 56.6+/-15.1 U/l (mean+/-S.D.), and this reference range was approximately the same as the ALP activity (55.0+/-14.5 U/l) of other blood groups. The same results were observed with MEG, DEA and EAE methods. CONCLUSIONS: These results suggested that the differences in ALP activity in blood group B or O secretors and other blood groups were closely related to the HIAP and NIAP levels.

Adolescent↗
PubMed1985

Phosphotyrosine and phosphoprotein phosphatase activity of alkaline phosphatase in mineralizing cartilage.

We used embryonic skeletal cartilage known to have high levels of alkaline phosphatase activity to determine whether growing cartilage has phosphotyrosine phosphatase activity and phosphotyrosinyl histone phosphatase activity at physiologic pH. Embryonic chick pelvic cartilage and fetal pig scapular growth-plate cartilage were assayed using phosphotyrosine as substrate at pH 7.5 and the amount of tyrosine generated measured. Both cartilage models had Km for phosphotyrosine between 6 to 24 mus mol/L. Phosphotyrosine phosphatase activity correlated with alkaline phosphatase activity as assessed by (1) distribution of histologic staining for alkaline phosphatase within the cartilages, (2) hormonal stimulation of cartilage alkaline phosphatase activity in vitro, (3) comparison of alkaline phosphatase and phosphotyrosine phosphatase activities in the presence of known inhibitors (vanadate, levamisole, homoarginine, and zinc), and (4) assaying chick epiphyseal cartilage alkaline phosphatase purified to homogeneity for phosphotyrosine phosphatase activity. Areas of cartilage with elevated alkaline phosphatase activity also had raised phosphotyrosine phosphatase activity. Triiodothyronine, a known stimulator of cartilage alkaline phosphatase, increased chick cartilage alkaline phosphatase activity 88% and phosphotyrosine phosphatase activity 106%, and stimulated porcine growth-plate cartilage alkaline phosphatase activity 91% and phosphotyrosine phosphatase activity 145% after 3 days of in vitro incubation. Each of the inhibitors block alkaline phosphatase and phosphotyrosine phosphatase activities. The purified alkaline phosphatase had a Km for phosphotyrosine of 18 mus mol/L and Vmax of 5700 nmol tyrosine/mg protein/h, which is well over 1000-fold higher than the phosphotyrosine phosphatase activity found in the above preparations of pelvic and scapular cartilage.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗