Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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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)

To determine whether choleretic infusions of bile acids modified the function or structure of the membrane of the bile canaliculus, sodium taurocholate (NaTc) or dehydrocholate (DHC) was infused into male rats at a rate of 80 mumoles per hour over an 18-hour period. Bile was collected by fistula and phospholipid and cholesterol content was measured in bile, liver homogenates, and isolated liver plasma membranes (LPM) enriched in bile canaliculi. Na+, K+-ATPase, Mg2+-ATPase, 5'-nucleotidase, and alkaline phosphatase activities were also measured in LPM. NaTc infusions enhanced cholesterol and phospholipid output in the bile in association with a significant increase in phospholipid in both LPM and liver homogenate. Although DHC infusions resulted in a comparable excretion of bile acid, phospholipid and cholesterol output in bile did not increase from control values and the concentration of these lipids in LPM and liver homogenate also did not change. However, LPM Na+, K+-ATPase significantly increased after DHC infusions compared to NaTc-infused animals or controls. Neither bile acid altered the activities of Mg2+-ATPase, 5'-nucleotidase, or alkaline phosphatase. Both bile acids increased the diameter of the lumen of the bile canaliculus as assessed by scanning electron microscopy and produced irregularities and outpouchings in the canalicular membrane. Diverticuli and loss of microvilli were most prominent with DHC infusions whereas canalicular side branching and the density of microvilli, either remained unchanged or increased following NaTc infusions. Although the morphologic findings are qualitative, the results of these studies indicate that chronic choleretic infusions of NaTc and DHC have divergent effects, not only on enzyme activities in liver plasma membrane, but on phospholipid composition and 3-dimensional structure. These findings suggest that bile acids may after biliary secretion not only through their osmotic effects, but by modifying lipids and enzymes in the membrane of the bile canaliculus.
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PMID:Effects of chronic choleretic infusions of bile acids on the membrane of the bile canaliculus. A biochemical and morphologic study. 13 67

The 5'-nucleotidase properties of isolated lymphocyte plasma membranes from young pig mesenteric nodes are described; nucleosides-5'-monophosphates are the substrates of this specific enzyme. Concanavalin A inhibits this enzyme; on the same membranes this mitogen does not affect alkaline phosphatase and activates the membrane bound (Ca2+) ATPase. The 5'-nucleotidase inhibition is due to a specific interaction of Con A with carbohydrate groups of the membrane; its high positive cooperativity suggests that the lectin promotes reorganization of the membrane bound 5'-nucleotidase. Solubilization of the 5'-nucleotidase does not prevent the effect of Con A and the solubilized enzyme is firmly bound by Con A-Sepharose 4B; these results suggest that Con A inhibits the enzyme by a direct interaction and that 5'-nucleotidase can be considered as an eventual receptor for the lectin.
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PMID:[5'-Nucleotidase activity of lymphocyte plasma membranes. Effect of concanavalin A]. 14 52

1. Pretreatment of frozon cryostat sections with formaldehyde or calcium ions inhibits diffusion of the plasma membrane enzymes 5' nucleotidase, ATP-ase and alkaline phosphatase during incubation. 2. Treatment of fixed sections with different kinds of buffer at 37 degrees C induces diffusion of enzyme activity from the plasma membrane to other sites of the section and into the incubation medium. This buffer influence depends on temperature: at 4 degrees C only a slight diffusion occurs. Addition of phospholipase C, digitonin or taurocholate to the buffer opposes the buffer effect. 3. Pretreatment of frozen cryostat sections with a mixture of equal parts of chloroform and acetone give a good fixation of the plasma membrane enzymes 5'-nucleotidase, ATP-ase, alkaline phosphate and leucyl-beta-naphthylamidase. During this treatment the different kinds of lipids present in the membrane are ex-racted equally. After this fixation buffer treatment does not cause a visible diffusion of enzyme activity in the section. Only a slight diffusion (1 till 7 percent) into the buffer solution takes place. 4. The mentioned treatments open up possibilities to get insight into the membrane anchorage of plasma membrane enzymes.
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PMID:Influence of fixation and buffer treatment on the release of enzymes from the plasma membrane. 14 99

Changes in activities of plasma membrane enzymes during liver regeneration may be related to the maintenance of hepatic function or to the regulation of cell proliferation. Plasma membranes were isolated from rat livers at various times after partial hepatectomy, and the specific activities of alkaline phosphatase, (Na+ + K+)-ATPase, leucine aminopeptidase, 5'-nucleotidase, and adenylate cyclase (basal and with glucagon or epinephrine) were measured. Alkaline phosphatase and (Na+ + K+)-ATPase activity increased 3.6-fold and 2-fold respectively, during the first 48 h after partial hepatectomy. The time of onset and duration of change suggest that these increases in activity are involved in the maintenance of bile secretion. Decreases in leucine aminopeptidase activity at 48--108 h and in 5'-nucleotidase activity at 12--24 h were observed, which may be involved in the restoration of protein and accumulation of RNA. The basal activity of adenylate cyclase increased after partial hepatectomy. The response of adenylate cyclase to epinephrine showed a transitory increase between 36 and 108 h after surgery, while the response to glucagon was decreased by approximately 50% at all time points through 324 h after surgery. These changes in the hormone responsiveness of adenylate cyclase are similar to those previously observed in fetal and preneoplastic liver.
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PMID:Changes in plasma membrane enzyme activities during liver regeneration in the rat. 14 24

Three parts were distinguished by electron microscopy and by enzyme histochemistry at the boundary zone between the white and red pulp of the human spleen. The first was the inner layer of the perifollicular region, composed of medium-sized lymphocytes with abundant free ribosomes in their cytoplasm. A small number of reticulum cells intervened among these lymphocytes. This inner layer was considered to correspond to the "Follikelaussenzone" (Strasser). The second was the outer layer of the perifollicular region, composed of a meshwork of reticulum cells with reticular fibers, and sheathed and non-sheathed arteries. Small and medium-sized lymphocytes, granulocytes, erythrocytes, platelets, and a small number of plasma cells were observed in the mesh spaces. This outer layer was considered to correspond to the "marginal zone" (Snook). At the outermost part of this layer, the venous sinus appeared. There was no distinct border between this layer and the red pulp. The third was the neighboring region of the periarterial lymphoid sheath, showeing similar structure and cellular components to the outer layer of the perifollicular region. It was characteristic feature for the lymphocytes and some of the reticulum cells of this region to have a strong activity for alkaline phosphatase reaction, while the lymphocytes of the outer layer showed only a weak activity. Adenosine triphosphatase and 5'-nucleotidase activities were demonstrated on the lymphocytes of these three parts of the boundary zone as well as the lymph follicle. Different activities for these enzyme reactions may indicate the functional properties of the B-cell system.
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PMID:An electron microscopic and enzyme histochemical study of the boundary zone between the white and red pulp of the human spleen. 14 41

On the basis of electron microscopic evidence, a preparation of microvilli obtained from the surfaces of placental villi was previously considered by us to represent syncytiotrophoplast plasma membrane. The present investigation was undertaken to obtain independent biochemical evidence on the nature of the preparation. Protein, lipid, carbohydrate, sialic acid, phospholipid and cholesterol concentration were determined and found to be consistent with analyses of membranes obtained from other sources. Enzyme membrane markers (5'-nucleotidase, (Na+ + K+)-ATPase and alkaline phosphatase) were also assayed, and found to be considerably enriched in the microvillous preparation compared to the whole placental homogenate. These findings, together with other evidence, support the contention that the preparation is indeed syncytiotrophoblast plasma membrane.
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PMID:Preparation and characterization of human syncytiotrophoblast plasma membrane. 15 76

The plasma membrane enzymes, alkaline phosphatase, bicarbonate-dependent adenosine triphosphatase, 5'-nucleotidase, and carbonate dehydratase, were measured in ductal and acinar preparations of bovine pancreas. Epithelial cells were scraped from the main duct and a piece of acinar tissue was dissected from the whole pancreas for homogenization. All enzymes studied demonstrated higher levels in the duct per milligram protein than in the acinus: bicarbonate-dependent adenosine triphosphatase was 2.8 times higher; 5'-nucleotidase, 4.1 times higher; carbonate dehydratase, 16.9 times higher, while alkaline phosphatase showed only a slight increase in the duct compared to acini.
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PMID:Enzymic profiles of bovine pancreatic ductal and acinar tissues. 15 38

In rats changes in plasma membrane enzyme activities due to Gal-N intoxication were studied by enzymehistochemical methods. The bile canalicular 5'-nucleotidase and nucleoside polyphosphatase activities decreased; the sinusoidal 5'-nucleotidase remained unchanged. The bile canalicular leucyl-beta-naphthyl-amidase showed an increase in activity; the alkaline phosphatase activity remained unchanged. In contrast to the spotty necrosis, changes in plasma membrane enzyme activities were seen in all liver cells, suggesting that changes of these activities, occurring after Gal-N treatment, do not correlate with cell death. The conclusion was drawn that the deviations of the enzyme activities might be due to changes in the lipid environment of the enzyme proteins in the membrane. With the exception of alkaline phosphatase, partial hepatectomy caused the same changes in enzyme activities as did Gal-N intoxication. Nevertheless Gal-N administration to partial hepatectomized rats did not lead to hepatic necrosis. Galactose given simultaneously or within two hours after Gal-N prevented both changes in plasma membrane enzyme activities and hepatocellular damage. This suggests an important role of galactolipids and galactoproteins in the plasma membrane alterations.
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PMID:A histochemical study about changes in rat liver plasma membrane enzyme activities after galactosamine administration. 15 4

We have examined the effect of chronic diabetes mellitus upon cell membrane composition and turnover in streptozotocin-treated rats and control animals maintained for four to eight weeks. Liver plasma membranes, prepared from diabetic animals, showed enhanced activities of alkaline phosphatase and glucose-6-phosphatase and depressed 5'-nucleotidase when compared with controls. Studies of the nonprotein constituents of liver plasma membranes and red cell "ghosts" showed similar changes in both tissues: sialic acid and cholesterol content were reduced in the membranes of diabetic animals, while phospholipids (total and individual classes) and neutral sugars were unchanged. To look for changes in relative turnover rates of individual membrane proteins, we combined a double-label in-vivo technic using [3H] and [14C] leucine with polyacrylamide gel separation of membrane proteins. No significant differences were observed between control and diabetic animals. In chronically diabetic animals, cell membranes may show significant changes in overall composition with no significant changes in the rate of protein turnover.
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PMID:Cell membrane changes in chronically diabetic rats. 16 76

The authors studied the modifications of the activities of some enzymes in cell cultures submitted to the action of biliverdin. This biliary pigment rapidly induces a remarkable increase in alkaline phosphatase and ATP-ase activities and subsequently, an activation of acid phosphatase and beta-glucuronidase. On the contrary, 5'-nucleotidase and glucose-6-phosphatase activities remain unchanged. These results are discussed and compared with those obtained in our and other laboratories by using unconjugated bilirubin on different biological substrates.
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PMID:A cytochemical study of some enzyme activities in biliverdin-treated cell cultures. 16 46


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