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Query: EC:3.1.3.1 (alkaline phosphatase)
 47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In 11 adult testes studied, about 0.3 to 4.6% of the total alkaline phosphatase activity was heat stable and L-phenylalanine sensitive but L-homoarginine insensitive. The testicular heat-stable enzyme was more susceptible to inhibition by L-leucine and ethylenediaminetetraacetate than were the normal placental and intestinal enzymes. By antibody-directed enzyme inhibition test, the testicular heat-stable enzyme cross-reacted completely with normal placental enzyme but clearly distinguished itself from a heat-stable component of normal intestinal enzyme. Thus, placental alkaline phosphatase D-variant is synthesized in testis, indicating that the gene for elaborating this placental protein is probably already active in the testicular cells. The high incidence of this protein in cancers of testis and ovary is probably due to its increased production by gonadal genes present in the genome of these particular tumors.
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PMID:Presence of the rare D-variant heat-stable, placental-type alkaline phosphatase in normal human testis. 615 31

To characterize the placental amino acid transport systems, L-alanine and L-leucine uptakes were studied using microvillous brush border membrane vesicles prepared from human placenta. The specific activities of alkaline phosphatase and 5'-nucleotidase in the membrane preparation were enriched 9-11 times as high as those in the homogenate. Intravesicular water (IVW) volume determined with 3-O-methyl-D-glucose was 0.59 microliters/mg protein. The saturation kinetics of L-leucine uptake by the vesicles equilibrated with Na+ gave a single set of Km (4.2mM) and Vmax (1.16 mumol/ml IVW/30s). These parameters were clearly different from those for L-alanine uptake reported previously (Asai et al.: Biochem. Int., 4:377, 1982). In the presence of an inward Na+-gradient L-leucine uptake was stimulated about 2 times, but transient accumulation was not observed differing from L-alanine uptake. Discrimination of the neutral amino acid transport systems in the presence of an inward 100mM Na+-gradient revealed that the relative contributions of A, ASC and L systems, and simple diffusion were 55, 20, 15 and 10% for L-alanine, and 45, 0, 15 and 40% for L-leucine, respectively. The results indicate that the neutral amino acid transport systems in the human placental microvillous membranes are clearly different between L-alanine and L-leucine.
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PMID:[Studies on the amino acid transport systems in the human placenta--L-alanine and L-leucine uptake by microvillous brush border membrane vesicles]. 629 24

The occurrence and nature of heat-stable placental-type alkaline phosphatase (Pl-ALP) in extracts from a variety of non-malignant human tissues has been investigated using monoclonal antibodies in a sensitive solid-phase enzyme immunoassay. The presence of Pl-ALP was confirmed in testicular, cervical and lung tissue extracts, and trace amounts were also detected in extracts from mammary and ovarian tissue. Evidence is presented that normal testis contains at least two forms of Pl-ALP, the major component being an L-leucine-inhibitable placental-like enzyme which is not the D-variant of Pl-ALP. These results have a bearing on the occurrence of Pl-ALP and placental-like ALP activity in malignancy.
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PMID:Demonstration of placental and placental-like alkaline phosphatase in non-malignant human tissue extracts using monoclonal antibodies in an enzyme immunoassay. 636 60

By means of enzyme immunoassays based on two monoclonal antibodies with specificities for distinct forms of placental type alkaline phosphatase (Pl-ALP), together with L-leucine inhibition studies, it has been possible to distinguish the Nagao type carcinoplacental enzyme from other placental type alkaline phosphatases. This approach has shown that it is the Nagao type (placental like) enzyme which is detectable in small amounts in the plasma of healthy individuals, particularly cigarette smokers.
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PMID:Serum placental type alkaline phosphatase in cigarette smokers. 637 80

Parallel changes in the enzyme activities of CA2+ATPase and alkaline phosphatase were observed in HeLa cells. Both enzymes were inhibited to a similar degree by L-phenylalanine, L-tryptophan, and L-leucine, while being relatively resistant to L-homoarginine. Exposure to heat (56 degrees C, 60 degrees C, and 65 degrees C) resulted in a loss of both enzyme activities. Both alkaline phosphatase and Ca2+ ATPase, when treated with EGTA, required Ca2+ for the restoration of activity. Cells grown in the presence of agents that affect alkaline phosphatase (dexamethasone, butyric acid, and hyperosmolar NaCl) showed similar changes in the activities of both enzymes.
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PMID:Similarities between alkaline phosphatase and Ca2+ ATPase activities in HeLa cells. 645 Jul 71

Boar sperm plasma membranes were purified by differential and sucrose density equilibrium centrifugation and were found to yield a single band at a density of 1.14 g/cm3. Both alkaline and acid phosphatase activities were enriched in this fraction. The alkaline phosphatase activity was optimal in 100 mM tris (hydroxymethyl) methylamine (Tris)-NaHCO3 at pH 9.9 with 0.05% Triton X-100 and 1 mM MgCl2. This activity was inhibited by ethylenediaminetetraacetic acid (EDTA), cadmium, zinc or heating at 60 degrees C for 30 min. Also, L-homoarginine caused approximately 70% inhibition and L-phenylalanine or L-leucine caused about 10 to 20% inhibition. Acid phosphatase activity was optimal in 100 mM sodium acetate at pH 5.1 with 0.05% Triton. Sodium dodecyl sulfate, potassium fluoride (KF) or sulfhydryl reagents inhibited the activity, while EDTA or heating at 60 degrees C had no effect. These data for enzymes from boar sperm plasma membranes can be used for future work on the quantitation of the enzymes, distinguishing these two phosphatases from other phosphohydrolases, purification of the enzymes and for comparison to phosphatases in other tissues.
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PMID:Some properties of acid and alkaline phosphates from boar sperm plasma membranes. 650 37

Rat peritoneal polymorphonuclear leukocytes accumulate radioactivity when incubated with 17 microM L[4,5-3H]leucine methyl ester; only low levels of accumulation are observed when the cells are incubated with equivalent amounts of labeled D-leucine methyl ester or the free amino acid, L-leucine. More than 98% of the intracellular radioactivity of cells incubated with leucine methyl ester is in the form of leucine. When cells that had been preincubated with L-leucine methyl ester were disrupted by sonication, 72% of the intracellular radioactivity could be trapped on glass fiber filters, indicating that the leucine had accumulated within a particulate intracellular compartment. Granule preparations obtained from the polymorphonuclear leukocytes accumulated leucine in the presence of leucine methyl ester in a manner similar to the intact cells. Separation by density gradient centrifugation of the granules obtained from cells preincubated with labeled leucine methyl ester revealed a nearly exact correspondence between the density distribution of accumulated radioactivity and that for beta-glucuronidase, an enzyme localized with the azurophilic subpopulation of polymorphonuclear leukocyte granules; there was no such correspondence with the activity of alkaline phosphatase, a marker for the specific granules. The results indicate that the azurophilic granules represent the intracellular site of leucine accumulation by the intact cells. This conclusion is supported by the effects of millimolar concentrations of amino acid methyl ester, which cause a dramatic loss of latency for the activities of the azurophilic granule enzymes beta-glucuronidase and myeloperoxidase but have no effect upon the latency of the specific granule enzyme alkaline phosphatase. Leucine accumulation by the intact cells is 80% inhibited by 0.1 mM chloroquine and 50% inhibited by 20 mM NH4Cl and methylamine, lysosomotropic agents that elevate the intralysosomal pH. These observations suggest that the azurophilic granules of these cells, generally considered to be primary lysosomes, are internally acidified.
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PMID:Accumulation of amino acids within intracellular lysosomes of rat polymorphonuclear leukocytes incubated with amino acid methyl esters. Evidence for the internal acidification of azurophilic granules. 668 51

A search for placental or placental-like human alkaline phosphatase (ALP) was made in human tissues. The tissue extracts were assayed for ALP before and after heating at 65 degrees C for 1 h. Trace amounts of heat-stable ALP activity (greater than 0.01 IU/g) were found in lung, testis, cervix and thymus. The heat-stable ALP in these four tissues gave in Ouchterlony double diffusion plates lines of apparent identity with placental ALP when a rabbit anti-human placental antiserum was used. Inhibition studies with L-phenyl-alanine (Phe), L-homoarginine (Har), L-phenylalanylglycylglycine (Pgg), L-leucine (Leu) and levamisole (Leva), were carried out on the heat-stable ALP and on the total ALP. The heat-stable ALPs from cervix and lung gave [I]50 values with each inhibitor comparable to those of placental ALP. The heat-stable ALPs froM testis and thymus gave [I]50 values for Leu and Pgg which were significantly different from the placental isoenzyme. Electrophoresis of heat-stable lung ALP from different individuals showed polymorphic differences similar to those seen with placental ALPs. Such differences were not seen with heat-stable testis ALP. We conclude that human non-malignant testis, cervix, lung and thymus tissues contain small amounts of placental or placental-like ALPs. The heat-stable ALPs in cervix and lung appear to have the same characteristics as placental ALP and are probably encoded by the same gene locus. The heat stable ALPs in testis and thymus, though immunologically very similar to placental ALP differ from it in inhibition profile and electrophoretically. The significance of the results in relation to the "ectopic' expression of placental and placental-like ALPs in malignancy is discussed.
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PMID:A search for trace expression of placental-like alkaline phosphatase in non-malignant human tissues: demonstration of its occurrence in lung, cervix, testis and thymus. 681 93

The Regan isoenzyme is a placental-type alkaline phosphatase that is expressed in a number of human tumors, particularly in gonadal and urologic cancers. Attention is given to the unique gene that codes for placental alkaline phosphatase and the similarities and differences in the tumor and placental gene products. The separation and identification of individual organ-specific isoenzymes is accomplished by a variety of biochemical, immunologic, and electrophoretic techniques and the correlation of the Regan isoenzyme, non-Regan isoenzyme, and Nagao isoenzyme, and the Kasahara isoenzyme is made with their developmental counterparts. The L-leucine-sensitivity phenotypes of placental and tumor alkaline phosphatases and the non-Regan early placental type alkaline phosphatases appear to be developmental phase-specific. Oncotrophoblast gene expression has been investigated with monophenotypic cell culture lines as a consequence of modulation by prednisolone and hyperosmolarity. Finally, general discussion of oncodevelopmental proteins as tumor markers precedes a current opinion of Regan isoenzyme as a tumor marker. Evidence now points to seminoma as a consistent producer of Regan isoenzyme although much more work will be required to establish its clinical utility.
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PMID:Immunology and biochemistry of the Regan isoenzyme. 702 57

Polymorphonuclear leukocytes were isolated from the peripheral blood of rabbits by Ficoll-Hypaque centrifugation followed by dextran sedimentation. The granulocytes were homogenized in isotonic sucrose and subjected to analytical subcellular fractionation by sucrose density gradient centrifugation. Leucine aminopeptidase, when assayed with L-leucine-7-amido-4-methyl-coumarin as substrate, showed a similar distribution to N-acetyl-beta-glucosaminidase and thus is localized to the tertiary granules. There was no leucine aminopeptidase associated with the plasma membrane of these cells. Further experiments with purified plasma membranes and inhibitor studies using diazotized sulphanilic acid further confirmed that leucine aminopeptidase had a purely intracellular localization. Vitamin B-12 binding protein showed a similar localization to alkaline phosphatase indicating that, as in human polymorphonuclear leukocytes, vitamin B-12 binding protein is located to the specific granules.
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PMID:Localization of leucine aminopeptidase and vitamin B-12 binding protein in rabbit peripheral blood polymorphonuclear leukocytes. 715 Jun 59


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