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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)

The Ca2+-binding glycoprotein isolated from preosseous cartilage shows also alkaline phosphatase activity. The purification procedure indicates that the enzyme is inhibited in crude extract and conceivably in the intact tissue; the activity may be controlled by the proteoglycans present in the matrix. Other substrates are hydrolyzed by the purified enzyme in addition to p-nitrophenylphosphate; the highest specific activity was measured with ATP and pyrophosphate (PPi) at pH 7.5 and 9.0 Mg2+ induces an activation of ATP and PPi hydrolysis; Ca2+ activates hydrolysis of ATP but inhibits that of PPi. The glycoprotein shows also transphosphorylase activity, L-serine being the best phosphate acceptor. The release or transfer of Pi catalyzed by the glycoprotein can be an important step in calcium phosphate precipitation.
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PMID:Enzymatic properties of the Ca2+-binding glycoprotein isolated from preosseous cartilage. 11 41

Alkaline phosphatase extracted from P. boryanum with lysozyme or polymyxin B treatment was used in a comparative study of cell bound and cell free enzyme. The effects of various ions on enzyme activity were tested. Calcium was found to enhance activity to the greatest degree stimulating the cell bound alkaline phosphatase 100% and cell free enzyme four-fold. Magnesium and potassium also stimulated the activity of cell bound and cell free enzyme. Other ions were found to be inhibitory to varying degrees.
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PMID:Effect of ions on the activity of the enzyme alkaline phosphatase from Plectonema boryanum. 12 Sep 24

1. Six rat liver plasma-membrane subfractions of different density and morphological, enzymic and chemical properties were prepared from homogenates by a combination of differential, rate-zonal and density-gradient centrifugation. They consisted of three vesicular 'light' subfractions of density 1.12-1.13 and three 'heavy' subfractions of density 1.16-1.18 containing membrane strips and intercellular junctions. 2. All six subfractions contained a basal adenylate cyclase activity. One of the 'light' subfractions that showed the highest glucagon-stimulated adenylate cyclase activity was identified as deriving form the blood-sinusoidal face of the hepatocyte. This subfraction, unlike the others, was contaminated by Golgi components, as indicated by its morphological properties and the presence of galactosyl- and sialyl-transferase activities. 3. All the six subfractions showed high activities of the following plasma-membrane marker enzymes: 5'-nucleotidase, alkaline phosphodiesterase (nucleotide pyrophosphatase), alkaline phosphatase, leucine naphthylamidase and Mg2+-activated adenosine triphosphatase. A 'light' subfraction that showed the highest specific activities of all the above marker enzymes, but lacked a glucagon-stimulated adenylate cyclase activity, was identified as deriving from the bile-canalicular face of the hepatocyte. 4. The 'heavy' subfractions, which showed generally the lowest activities of the above plasma-membrane enzyme markers, and were characterized by the presence of desmosomes and gap junctions, were taken to originate from the contiguous faces of the hepatocyte. 5. The protein composition of the six subfractions was generally similar, as shown by polyacrylamide-gel electrophoresis. Differences in the amounts of various protein and glycoprotein bands among the subfractions correlated with their morphology, enzymic composition and sialic acid content. 6. Hormonal and histochemical evidence supporting the identification of a bile-canalicular subfraction, a blood-sinusoidal subfraction and contiguous-face subfractions is discussed.
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PMID:Functional polarity of the rat hepatocyte surface membrane. Isolation and characterization of plasma-membrane subfractions from the blood-sinusoidal, bile-Canalicular and contiguous surfaces of the hepatocyte. 12 84

Following the formation of hyperplastic nodules at a late stage of azo dye hepatocarcinogenesis, some areas of parenchyma show an intense RNA staining, and such hyperbasophilic foci apparently develop hepatomas. Radioautographic analyses with [3H]thymidine labeling indicate the foci to be areas of continued cell proliferation, and the hepatocytes are morphologically distinguishable from the surrounding tissue. The increase of basophilia occurs simultaneously with histochemically demonstrable decreases in bound cations and concomitant increases in pyroantimonate-precipitable free cations. Thus, the phenomenon of hyperbasophilia and the ensuing alteration of cell cycle appears to be associated with changes in intracellular homeostasis. Ultrahistochemical localizations of adenosine triphosphatase and alkaline phosphatase suggest topographic alterations of membrane enzyme activities in the foci and the persistence of altered patterns during tumor progression. The developmental feature of surface adenosine triphosphatase activity has been further studied with subcultures of epithelial cells, which were derived from normal and precancerous livers. The enzyme activity of nontumorigenic cells is minimal, while a considerably high activity is detectable in situ at the outer surface of plasma membranes of tumorigenic cells. A Ca2+- Mg2+-dependent adenosine triphosphatase is identified at the cell surface, and the ectoenzyme would be a useful marker for detection of malignant liver epithelial cells.
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PMID:Ultrastructural and cytochemical studies on hyperbasophilic foci with special reference to the demonstration of cell surface alterations in hepatocarcinogenesis. 13 71

Human adult lung fragments removed from macroscopically undamaged and anthracosis exempted zones of lungs of 20 pneumonectomies made for cancer, were tested for 25 enzymic activities. The location and intensities of these enzymic activities were different in the lung tissue components; The bronchial epithelia contained highly active LDH, MDH, SDH, NADH-TR and NADPH-TR, glucose-6-phosphate dehydrogenase, active hydroxyproline-2-epimerase, alkaline phosphatase. Ca2+-activated ATP-ase, and beta-galactosidase. Bronchial and vascular muscles presented intense activities of LDH, MDH and SDH of alkalinephosphatase, AMP-ase and Ca2+-activated ATP-ase, as well as of beta-galactosidase. The alveolar walls presented high activities of SDH, MDH and LDH, of alkaline and acid phosphatases, of beta-galactosidase and of Tween-40 and 60-esterases, of HEP, cytochrome-oxidase and peroxidase. The free alveolar macrophages were active for LDH, MDH, SDH, NADH-TR and NADPH-TR, G1-6-ph-DH, acid and alkaline phosphatase, cytochrome-oxidase and peroxidase, HEP, AMP-ase and Mg2+-activated ATP-ase, Tween-esterases, naphthol-ASD-acetate esterase, and beta-galactosidase. The endothelia contained high activities of alkaline phosphatase, of AMP-ase and Mg2+-activated ATPase, of LDH, MDH and SDH, and of beta-galactosidase. In bronchial lymphoid nodules it was the LDH, MDH, SDH, cytochrome-oxidase and peroxidase, HEP, alkaline phosphatase and AMP-ase, Tween-60-esterase and beta-galactosidase that were active. The interlobular areas of the lung presented intense activities of SDH, MDH, LDH, HEP and cytochrome-oxidase. The activities of the other tested enzymes were weaker or absent in the adult human lung components, the same as those of aminopeptidases which were present only in some free alveolar macrophages. The discussion of some relationships between these enzymic actitivies and the morphology of the human adult lung tissue asserted that the latter could not be considered as a "normal" tissue but as one overstrained by the components of blood and polluted air.
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PMID:Histoenzymology of the lung. I. Enzyme activities of the lung tissue of acult humans; relationships between structure and functions. 14 Mar 14

(1) The basiconic sensilla on the antennae of Calliphora resemble other insect epidermal sensilla; one or several bipolar sense cells are surrounded by three non-neural cells. (2) The apical cell membrane of the tormogen cell (one of the three accessory cells) forms microvilli coated internally with particles. (3) In the (extracellular) outer receptor-lymph space hyaluronic acid can be demonstrated histochemically. (4) Demonstration of non-specific alkaline phosphatase, Mg2+-activated ATPase, and the presence of mitochondria in the apical part of the tormogen cell suggest active transport processes through these cells into the outer receptor-lymph space.
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PMID:Tormogen cell and receptor-lymph space in insect olfactory sensilla. Fine structure and histochemical properties in Calliphora. 14 70

The same isoenzyme of nonspecific alkaline phosphatase (APase), assayed with p-nitrophenylphosphate (p-NPP), was shown be present in different calcifying tissues, bone, calcifying cartilage, odontoblasts and enamel organ. Indications were also found that the enzymatic degradation of inorganic pyrophosphate (PPi) in calcifying tissues is mediated by APase. By using specific APase inhibitors, it was shown that two enzymes capable of degrading ATP exist. These were characterized in dentinogenically active odontoblasts, and it was concluded that one is the classical APase, the other is a Ca2+ and Mg2+ activated ATPase, named Ca2+-ATPase. The two phosphatases were solubilized from odontoblasts and separated. The localization of APase and Ca2+-ATPase in odontoblasts was investigated by subcellular fractionation and EM histochemistry. Routine methods for fixation were found to almost completely inactivate the enzymes. By using a mild fixation technique that preserved 80% of the enzyme activity, the main localization for both APase and Ca2+-ATPase was found to be in the membranes of intercellular vesicles located in the cell body and odontoblasts process. No activity was found in the cell membranes. It is concluded that there are at least two enzymes able to degrade phosphate compounds at alkaline pH in hard tissue forming cells. One is the nonspecific alkaline phosphatase (APase; EC 3. 1. 3. 1), which is active against p-NPP, PPi, glycerophosphates and ATP among other substrates. The other is a more specific Ca2+-ATPase (EC 3. 6. 1. 3). There seems to be an intimate relation between these two enzymes in the tissue. The function of APase in biological calcification is still obscure. In contrast, the finding of an ATP dependent, intravesicularly directed, transmembranous Ca2+-transport in vesicles derived from the microsomal fraction of odontoblasts may explain the role of Ca2+-ATPase.
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PMID:Odontoblast alkaline phosphatases and Ca2+ transport. 15 9

Ca2+-ATPase activity was solubilized, partly purified, and separated from nonspecific alkaline phosphatase activity (APase1) of dentinogenically active rat incisor odontoblasts. Attempts were made to extract the enzymes by various agents, such as Triton X-100, deoxycholate, butanol, EDTA, and buffers of decreasing ionic strength. Solubilization by butanol followed by extraction with low concentrations of EDTA proved to be most effective. Purification and separation were done by molecular sieve chromatography. Ca2+-ATPase showed no activity against p-nitrophenyl phosphate (p-NPP) or inorganic pyrophosphate (PPi) and was unaffected by R 8231 [+/-)-6(m-bromophenyl)-5,6-dihydroimidazo(2,1-b)thiazole oxalate]. It was activated by Ca2+ and Mg2+ ions in equimolar concentrations with the substrate. The enzyme was rapidly inactivated in the solubilized state. An apparent molecular weight of about 18,000 was obtained from molecular sieve data. APase, showing activity against ATP, PPi, and p-NPP, was virtually totally inhibited by R 8231. It was activated by Mg2+ ions but slightly reduced in activity by Ca2+ ions. It had an apparent mol. wt. of 79,000. The results provide direct evidence for earlier suggestions of the existence in hard tissue forming cells of two phosphatases active at alkaline pH.
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PMID:Separation of odontoblast Ca2+-ATPase and alkaline phosphatase. 15 25

Plasma membranes were isolated from the yeast and mycelial forms of Candida albicans as described previously (Marriott, 1975) and examined for the presence of several enzymes. Measurement of specific activities showed enrichment of Mg2+-dependent and Ma+/K+-stimulated Mg2+-dependent adenosine triphosphatase and mannan synthetase, in the plasma membrane fractions from both morphological forms of the organism. However, acid and alkaline phosphatase, NADH oxidase and 5'-nucleotidase showed no such specific location.
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PMID:Enzymic activity of purified plasma membranes from the yeast and mycelial forms of Candida albicans. 17 Mar 63

The activity of a pyrophosphate-splitting tissue factor in jaws, teeth and intestinal mucosa has been studied by means of histochemistry. Freeze-cut, unfixed sections of whole animals were incubated in a buffered medium (pH 8.6) containing inorganic pyrophosphate (PP) Pb2+, Mg2+, and Zn2+ at various concentrations. The effects of compound R 8231, heat, aldehyde fixation, and demineralization with EDTA were also investigated. In sections showing optimal staining, deposition of incubation products was found in the stratum intermedium and the subodontoblastic cells of the developing tooth, in the osteoblastic layers, and at the surface of the intestinal mucosa. The hard tissues were also stained except in the demineralized sections. Treatment with heat or compound R 8231 resulted in loss of originally observed soft tissue staining while short-time demineralization with EDTA enhanced the staining reaction. It is argued that a nonspecific deposition of the capturing ion, Pb2+, can hardly explain the observed soft tissue staining. The results point to the presence of a PP-splitting enzyme, and it is suggested that the enzyme exhibits features of an alkaline phosphatase with PP-phospholhydrolytic properties rather than of an inorganic pyrophosphatase.
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PMID:Histochemical localization of alkaline pyrophosphate- phosphohydrolase in tooth-forming cells of rat. 17 19


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