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)

A prominent galactose-1-phosphatase was isolated from rat brain and partially purified by chromatography on diethylaminoethyl-Sephacel, hydroxylapatite, and Sephacryl S-300 columns. The galactose-1-phosphatase was separated from alkaline phosphatase, and from two forms of glucose-1-phosphatase. The three columns gave a 10-fold increase in specific activity to 290 mol/min/mg of protein, with a yield of 15%. Of the eight sugar phosphates tested, galactose-1-phosphate was the best substrate for the purified enzyme, followed by glucose-1-phosphate, which was hydrolyzed 40% as rapidly as galactose-1-phosphate. Galactose-1-phosphatase had an optimum pH of 8.5 and a Km value of 2.5 mM for galactose-1-phosphate hydrolysis. Mg2+ was required for activity, and supported half-maximal activity at a concentration of 1.25 mM. Phosphate was the only potent inhibitor found ATP, arsenate, and vanadate caused moderate inhibition of 10 mM levels, whereas AMP, L-homoarginine, and L-phenylalanine stimulated enzyme activity. Galactose-1-phosphatase was determined to have a Stokes radius of 30 A and a sedimentation coefficient of 4.1S. These values were used to calculate a molecular weight of 50,200 and a frictional ratio showing the enzyme to be a globular protein. It is hypothesized that a similar phosphatase may play a role in reducing brain galactose-1-phosphate concentrations in patients with galactosemia.
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PMID:Galactose-1-phosphatase in rat brain. 164 51

The phosphorylated monosaccharide, mannose-6-phosphate (M6P), causes a dose-dependent stimulation of alkaline phosphatase production by osteoblasts. The concentrations tested ranged from 0.1 to 30 mM. A maximal effect was reproducibly seen at 10-30 mM, and represented a 30% stimulation over control cells. Glucose-6-phosphate and fructose-1-phosphate also stimulated osteoblast alkaline phosphatase production, but not to the same extent as M6P. Sugar residues such as mannose, mannose-1-phosphate, and fructose-6-phosphate had no effect. The stimulatory effect of M6P is similar to that seen with insulin-like growth factor II(IGF-II). However, increasing doses of IGF-II did not further stimulate or add to the effect of 10 mM M6P. These data indicate that the mechanism for the transduction of the stimulatory signal may be similar for both IGF-II and M6P. They do not address, however, the possibility of separate or similar binding sites for the two agents. A specific polyclonal antibody to the IGF-II/cation-independent mannose-6-phosphate receptor (IGF-II/CI-MPR) elicits the same effects as M6P and IGF-II in these bone cells. Non-immune serum used as a control does not have any effect. These results suggest that activation of the osteoblast IGF-II/CI-MPR by either M6P or a specific antibody can evoke a biological response similar to that observed with IGF-II.
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PMID:Activation of osteoblast insulin-like growth factor-II/cation-independent mannose-6-phosphate receptors by specific phosphorylated sugars and antibodies induce insulin-like growth factor-II effects. 166 83

The activity of various enzymes and transport systems was studied in renal brush-border membrane vesicles (BBMV) isolated from rats injected daily with cyclosporin. Alkaline phosphatase (AP) was strongly stimulated: 55 and 113% increases were obtained in BBMV isolated from rats injected with 10 mg cyclosporin/kg for 5 and 10 days. The affinity of the enzyme remained unaltered, but maximal activity (Vmax) showed a strong increase of 2.4-fold between control and treated animals. In addition to the phosphatase activity, phosphate binding to AP also showed a dose-dependent stimulation by cyclosporin treatment: 44 and 70% increases in animals treated for 5 days with 5 and 10 mg cyclosporin/kg. However, the activity of aminopeptidase M was not affected by these treatments, and polyacrylamide gel electrophoresis of BBMV revealed no alterations in the profile of membrane proteins, suggesting the specificity of cyclosporin interaction with alkaline phosphatase. Na(+)-dependent amino acid and D-glucose transport systems remained unaffected by cyclosporin treatment. The Na(+)-independent transport system for lysine and the Na(+)-H+ antiporter activity were also unaltered. In contrast, the initial rate of phosphate uptake decreased by 28% after administration of cyclosporin (10 mg/kg) for 5 days: the Michaelis constant (Km) and Vmax decreased from 137 to 85 microM and from 1.49 to 1.07 pmol.micrograms-1.5 s-1, respectively. "In vitro" studies with membranes isolated from untreated rats were also undertaken by preincubating membranes with cyclosporin. Neither alkaline phosphatase nor the transport systems were affected under these conditions.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cyclosporin inhibits phosphate transport and stimulates alkaline phosphatase activity in renal BBMV. 167 93

Temporary occlusion of hepatic inflow is a useful maneuver to reduce hemorrhage from liver trauma and difficult hepatic resections. The liver can be protected with a hepatic protective solution before inflow occlusion, just as the stopped heart is protected by a cardioplegic solution during open heart surgery. Twenty dogs were divided into two groups. The portal inflow of group A was infused via the mesenteric venous branch with a hepatic protective solution composed of 250 mg of hydrocortisone, 15 mEq of KC1, 6 mL of 0.1 N HC1, 5 mL of 10% magnesium sulfate and 250 mg of dextrose in one liter of cold lactated Ringer's solution. Group B was infused with cold lactated Ringer's solution as a control. The hepatic artery and portal vein were isolated and then clamped for 30 minutes. The elevation of serum GOT and GPT after release of the clamps was significantly greater in group B, especially during the first 48 hours. The levels of alkaline phosphatase and total bilirubin were also higher in group B until the 7th day. The results liver biopsies 3 hours after release of the clamps revealed marked congestion and destruction of hepatocytes in group B. We conclude that liver perfusion with a hepatic protective solution before inflow occlusion results in less damage to liver tissue and less impairment of liver function. Such protection is important in liver surgery.
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PMID:Protection of liver ischemia due to inflow occlusion using prior perfusion with hepatic protective solution in dogs. 168 52

We describe the culture of human term placental trophoblast cells on cell-free amniotic membrane, with medium on both sides. Over the course of 2 days, the isolated cells, initially simple, mononucleated and probably cytotrophoblast, form a confluent layer of multinucleated syncytial cells with morphological and immunocytochemical properties of syncytiotrophoblast. This layer becomes polarized with respect to morphology, alkaline phosphatase distribution and hCG secretion. Contamination with amnion cells, and with other cell types that are present in placental tissue, was less than 1 per cent. A preliminary investigation of the permeability properties of the preparation showed that the trophoblast cell layer, rather than the amniotic membrane, was rate-limiting to transtrophoblast transfer, but that possible effects of the supporting membrane should be considered. The transtrophoblast transfer of D-glucose and the non-metabolisable analogue, 3-O-methyl-D-glucose (3OMG), had saturable and non-saturable/leak components in both directions, indicating that carrier-mediated processes were involved. The non-metabolisable amino acid 2-aminoisobutyrate (AIB) was both accumulated within the trophoblast cells, and transferred by saturable and non-saturable processes from the microvillous side, but no saturable accumulation or transfer was observed from the basal side, at the concentrations tried. The results suggest that this model may prove suitable for studies of transtrophoblast transfer.
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PMID:Two-sided culture of human placental trophoblast. Morphology, immunocytochemistry and permeability properties. 170 71

The structure of the linkage region of chondroitin sulfate chains attached to the hybrid proteoglycans of the Engelbreth-Holm-Swarm mouse tumor was investigated. The peptidoglycan fraction which contains oversulfated chondroitin sulfate rich in the GlcA beta 1-3GalNAc-4,6-diO-sulfate unit and undersulfated heparan sulfate rich in GlcA beta 1-4GlcNAc and GlcA beta 1-4GlcN-2N-sulfate units was isolated after exhaustive protease digestion of the acetone powder of the tumor tissue, (GlcA, glucuronic acid; GalNAc, 2-deoxy-2-N-acetylamino-D-galactose). Glycosaminoglycans were released by beta-elimination using NaB3H4 and digested with chondroitinase ABC. The linkage region fraction was separated from heparan sulfate by gel filtration and fractionated by HPLC on an amine-bound silica column. Six radiolabeled compounds (L1-L6) were obtained and structurally analyzed by cochromatography with authentic hexasaccharide alditols recently isolated by us from the linkage region, and by digestion using chondroitinase ACII, alkaline phosphatase and beta-galactosidase in conjugation with HPLC. These compounds shared the conventional hexasaccharide backbone structure: delta GlcA beta 1-3GalNAc beta 1-4GlcA beta 1-3Gal beta 1-3Gal beta 1-4Xyl-ol, (delta GlcA, delta 4.5-GlcA or D-gluco-4-enepyranosyluronic acid). L1 was not sulfated or phosphorylated. L2 and L4 were monosulfated at C-6 and C-4 of the GalNAc residue, respectively. Upon alkaline phosphatase digestion, L3, L5 and L6 were converted to L1, L2 and L4, respectively. Analysis of the periodate oxidation products indicated that the phosphate group in L3, L5 and L6 is located at C-2 of Xyl-ol. These results suggest that Xyl-2-O-phosphate is associated with both 4-O-sulfated and 6-O-sulfated GalNAc units and does not directly determine the sulfation pattern of chondroitin sulfate.
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PMID:The phosphorylated and/or sulfated structure of the carbohydrate-protein-linkage region isolated from chondroitin sulfate in the hybrid proteoglycans of Engelbreth-Holm-Swarm mouse tumor. 174 Jan 53

Leukocytic dehydrogenases (succinate and alpha-glucose phosphate dehydrogenases) and acid and alkaline phosphatase hydrolases activities were cytochemically assayed in 20 healthy women with normal menstrual cycles (controls) and 34 ones with habitual abortions. Ovulation in health was associated with a significant elevation of SDH, alpha-GPDH, and alkaline phosphatase activities. The second peak of enzymic activation, less marked, was recorded on days 20-24 of the cycle. Acid phosphatase activity was reduced by the second phase of the cycle. In women with habitual abortions the activities of redox enzymes (SDH and alpha-GPDH) reduced as against the controls (p less than 0.05, less than 0.01, less than 0.001), and no ovulatory peak of enzymic activation was detectable. The curves of enzymic activities were in good correlation with rectal temperature curves of the examinees. Elevated enzymic activities during ovulation and in the second phase of a normal cycle evidenced a sufficiently high energy supply of these processes. The detected reduction of leukocytic enzymic activities in women with habitual abortions may be used for the early diagnosis of an unfavorable pregnancy course and, possibly, for the prediction of placental insufficiency.
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PMID:[Characteristics of enzyme activity of leukocytes in women with history of habitual abortion]. 178 36

Fractionation of bone and liver alkaline phosphatase (EC 3.1.3.1; ALP) in serum by serial lectin affinity chromatography has demonstrated differences in the sugar chain structure of bone and liver ALP in serum from that previously reported in the corresponding tissues, with a lower content of high mannose or hybrid-type sugar chains and a higher content of biantennary complex-type chains. Furthermore, the bone and liver ALPs were found to differ in the latter with the bone fraction showing a greater content of fucose residues.
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PMID:Sugar chain heterogeneity of bone and liver alkaline phosphatase in serum. 180 67

Changes in intestinal transport of L-amino acid and D-glucose in streptozotocin (STZ)-induced hyperglycemic guinea-pig were examined using brush-border membrane vesicles. The vesicles were prepared from guinea-pigs on days 3, 10, and 21 after intravenous injection of STZ (150 mg/kg body weight), and from control animals injected with sodium citrate buffer (pH 4.5) in the same manner. Blood glucose concentration rose to greater than 300 mg/dl in the hyperglycemic guinea-pigs 24 h after STZ injection, and then remained constant. All vesicles obtained under different conditions showed a similar specific activity of alkaline phosphatase, a marker enzyme of the intestinal brush-border membrane, indicating a similar purity of the membrane vesicles. On day 3, Na(+)-dependent amino acid transport was found to be approx. 30% higher in the hyperglycemic than in the control group, and Na(+)-dependent glucose transport was 35% lower in the hyperglycemic than in the control group. On days 10 and 21, Na(+)-dependent amino acid transport had recovered to the control levels, whereas Na(+)-dependent glucose transport was twice as high as in the hyperglycemic than in the control group. Na(+)-independent amino acid and Na(+)-independent glucose transport showed no difference between the hyperglycemic and control groups after STZ injection. The changes in both Na(+)-dependent amino acid and glucose transport were attributed to significant changes in the Vmax values with no change in the apparent Km values. This study clearly demonstrates that hyperglycemia is associated with reciprocal changes in intestinal transport of amino acid and glucose in its acute phase, suggesting an important pathophysiological regulatory mechanism for absorption of nutrients by control of the numbers of specific carriers.
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PMID:Changes in amino acid and glucose transport in brush-border membrane vesicles of hyperglycemic guinea-pig small intestine. 182 12

Secretory vesicles that accumulate in the temperature-sensitive sec6-4 strain of yeast have been shown to contain a vanadate-sensitive ATPase, presumably en route to the plasma membrane (Walworth, N. C., and Novick, P. J. (1987) J. Cell Biol. 105, 163-174). We have now established this enzyme to be a fully functional form of the PMA1 [H+]ATPase, identical in its catalytic properties to that found in the plasma membrane. In addition, the secretory vesicles are sealed tightly enough to permit the measurement of ATP-dependent proton pumping with fluorescent probes. We have gone on to exploit the vesicles as an expression system for site-directed mutants of the ATPase. For this purpose, a sec6-4 strain has been constructed in which the chromosomal PMA1 gene is under control of the GAL1 promoter; the mutant pma1 allele to be studied is introduced on a centromeric plasmid under the control of a novel heat shock promoter. In galactose medium at 23 degrees C, the wild-type ATPase is produced and supports normal vegetative growth. When the cells are switched to glucose medium at 37 degrees C, however, the wild-type gene turns off, the mutant gene turns on, and secretory vesicles accumulate. The vesicles contain a substantial amount of newly synthesized, plasmid-encoded ATPase (5-10% of total vesicle protein), but only traces of residual wild-type PMA1 ATPase and no detectable mitochondrial ATPase, vacuolar ATPase, or acid or alkaline phosphatase. To test the expression strategy, we have made use of pma1-105 (Ser368----Phe), a vanadate-resistant mutant previously characterized by standard methods (Perlin, D. S., Harris, S. L., Seto-Young, D., and Haber, J. E. (1989) J. Biol. Chem. 264, 21857-21864). In secretory vesicles, as expected, the plasmid-borne pma1-105 allele gives rise to a mutant enzyme with a reduced rate of ATP hydrolysis and a 100-fold increase in Ki for vanadate. Proton pumping is similarly resistant to vanadate. Thus, the vesicles appear well suited for the production and characterization of mutant forms of the PMA1 [H+]ATPase. They should also aid the study of other yeast membrane proteins that are essential for growth as well as heterologous proteins whose appearance in the plasma membrane may be toxic to the cell.
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PMID:Expression of the yeast plasma membrane [H+]ATPase in secretory vesicles. A new strategy for directed mutagenesis. 182 8


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