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)

The enzyme alkaline phosphatase (AP) (EC 3.1.3.1) in three different calcification areas was studied by means of a spectrophotometric micro method using p-nitrophenylphosphate as a substrate. Rat maxillary incisor odontoblasts and enamel organ from the zones of matrix formation and maturation and tissue from rabbit metatarsal cartilage were allowed to react with the substrate in glycine-NaOH buffer at room temperature. The reaction was found to be linear for a minimum of 20 min. The pH optima for AP from these tissues were in the pH range of 10.0-10.3. In order to compare AP from the four calcification areas different parameters were studied. Heating at 56 degrees C or 60 degrees C for varying times revealed that the enzymes were almost completely inactivated after 10 min. Mg2+ ions activated the enzymes by about 25% at concentrations of 2.5 mM (enamel organ 1.25 mM); while only higher concentrations of Mg2+ had an inactivating effect, Ca2+ and PO3-4 ions were inactivating at varying concentrations. F- ions showed no effect on AP activity at concentrations below 250 mM (enamel organ 125 mM) but caused inactivation of the enzymes at about 50% at 1 M. EDTA was found to be a very effective AP inactivator at concentrations above 0.06 mM, whereas urea did not noticeably affect the enzyme reactions at concentrations below 1 M. At higher concentrations, inactivation was observed. In order to determine AP localization in the epiphyseal plate successive 40-mum-thick, freeze-sectioned slices were analyzed. The activity was highest nearest the zone of cartilage calcification and decreased towards the reserve cell zone. It was concluded that the same AP isoenzyme is present in these quite different calcification loci.
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PMID:A comparative study of alkaline phosphatase in calcifying cartilage, odontoblasts and the enamel organ. 1 71

The effect of furosemide, a potent inhibitor of active sodium transport, on the amount and composition of bile was studied in the dog. Ten milligrams per kilogram of body weight of furosemide were injected intravenously to anesthetized dogs with a previously constructed fistula of the common bile duct. In all dogs, a 2.5 times increase in bile flow was observed concomitant with a 15 times increase in urinary output. The amount of bile flow decreased gradually and returned to control levels 60 to 75 minutes after furosemide injection. The choleretic effect was associated with a high increase in sodium, chloride and bicarbonate anions and with a smaller increase in potassium, phosphorus and calcium. The total amount of bilirubin alkaline phosphatase and cholesterol was not significantly affected, while the calculated output of inorganic salts increased. The results indicate that inhibition of sodium reabsorption by furosemide simultaneously affects the liver and kidney and that the increase in electrolyte solution is most likely caused by the inhibition of sodium reabsorption in the ductuli. Furosemide also may interfere with the sodium mediated secretory fraction at the canalicular level, but the predominant factor determining the increase in bile flow and electrolytes is inhibition of sodium reabsorption in the biliary ducts and ductuli.
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PMID:The effect of furosemide on the flow and composition of bile in the dog. 1 26

The ATP-splitting enzyme activity in odontoblasts isolated from rat incisors has been studied by means of a radiochemical and a colorimetric micromethod. The results with the two methods were virtually identical. The reaction was linear with time for at least 45 min. The pH optimum was found to be 9.8 independently of the ATP concentration. Maximal substrate saturation occurred at a total ATP concentration of 3 mM. Ca2+ and Mg2+ ions activated ATP degradation. F-ions did not affect the activity at low concentrations, whereas higher concentrations were inhibitory. Na+ and ions were slightly inhibitory. Urea inhibited the enzyme activity at concentrations above 1.5 M, while EDTA and EGTA were strong inhibitors at very low concentrations. When incubating in the presence of low concentrations of specific inhibitors for nonspecific alkaline phosphatase, levamisole and R8231, about 20% ATP degrading enzyme activity remained. In conclusion it is suggested that there are at least two ATP degrading phosphatases active at alkaline pH.
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PMID:ATP-ase activity in the odontoblastic layer of rat incisor. Determination with a radiochemical and a colorimetric method. 1 93

The binding of Ca2+ to a salivary phosphoprotein, protein C, was studied by equilibrium dialysis. In 5mM-Tris/HCl buffer, pH 7.5, protein C bound 190 nmol of Ca2+/mg of protein. The apparent dissociation constant, K, was determined to be 1.9 x 10(-4)M and the binding of Ca2+ to the protein was non-co-operative. The binding of Ca2+ to protein C apparently depends on groups which ionize above pH 5.0. Ca2+ binding decreased with increased concentration of the dialysis buffer and on addition of SrCL2, MgCl2 and MnCl2 to the dialysis buffer. Digestion of protein C with trypsin or collagenase or heating of the protein to 60 degrees or 100 degrees C had little or no effect on the Ca2+ binding. Digestion of protein C with alkaline phosphatase caused a decrease in the amount of protein-bound Ca2+. This was also found for another salivary phosphoprotein, protein A. In the absence of Ca2+ the S020,w for protein C was 1.29 S and in the presence of Ca2+ it was 1.46S. Ca2+ may cause a conformational change in the protein or an aggregation of the protein molecules. No conformational changes of protein C in the presence of Ca2+ could be detected by circular dichroism or nuclear magnetic resonance.
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PMID:The binding of calcium to a salivary phosphoprotein, protein C, and comparison with calcium binding to protein A, a related salivary phosphoprotein. 1 96

The gastric acid output was studied in the 11 patients of hyperparathyroidism before and after parathyroidectomy. The gastric acid output before operation was almost equal to the normal control in our hospital. After the correction of serum calcium by parathyroidectomy, the gastric acid output and serum gastrin were decreased. The decreased gastric acid output was recovered as the days passed since operation and approached to the preoperative level. The acid output in hyperparathyroidism was less in the case whose activity of alkaline phosphatase was more, which suggested that the calcium deposition on gastric mucosa might damage the parietal cell as the result of long lasting hypercalcemia.
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PMID:The further investigation on the gastric acid secretion in the primary hyperparathyroidism. 2 34

Homogenates of human polymorphonuclear leucocytes (granulocytes) contain a Ca2+-dependent phospholipase A with optimal activity pH7.0. This enzyme is membrane-bound and is enriched in crude cytoplasmic-granule fraction. Ratezonal centrifugation of the cytoplasmic-granule fraction demonstrates that the phospholipase A is associated not only with specific- and azurophilic-granule populations but also with an 'empty' vesicular fraction containing 85% of the total alkaline phosphatase activity of whole homogenate. Thus this phospholipase is associated with granule as well as with other cellular membranes of human granulocytes.
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PMID:Phospholipase A activity associated with membranes of human polymorphonuclear leucocytes. 2 68

The extent and dynamics of changes by short (1 min) or prolonged (6 min) tourniquet application while obtaining venous blood samples were analysed with respect ot 33 frequently measured constituents of blood and serum. After 6-minute tourniquet application the values for red cells, haemoglobin, packed cell volume, total protein, albumen, gamma-glutamyl transferase, alkaline phosphatase, lactate dehydrogenase, creatinekinase, bilirubin, cholesterol, total glycerol and calcium increased by an average of 4-9%. One-minute tourniquet application did not have a significant effect. Levels of sodium, potassium, carbon dioxide, creatinine, uric acid, ratio of electrophoretic fractions and the MCV, MCH and MCHC indices were not affected even by 6-minute tourniquet applications. The introduction of blood sampling under standardised conditions is proposed.
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PMID:[Standardisation of obtaining blood samples: influence of tourniquet application on 33 constituents of blood and serum (author's transl)]. 2 36

The clinical and biochemical response to 25-hydroxycholecalciferol (25-HCC) and vitamin D3, 150 microgram/day for 20 days has been compared in infants aged 3--18 months with nutritional rickets. The infants were allocated at random to Group I (11 infants) treated with 25HCC and Group II (9 infants) treated with vitamin D3. In addition 15 matched control children without rickets were allocated to Group III and received 25-HCC 75 microgram/day for 20 days. Preliminary studies showed that plasma calcium, phosphorus, alkaline phosphatase and urine pH all differed significantly between the rachitic and control groups. The biochemical parameters in both groups of rachitic children became normal after treatment with the exception of plasma alkaline phosphatase which remained elevated. The control group showed a significant increase in plasma and urine calcium values in spite of the low dose of 25-HCC. The findings suggest that 25-HCC is as effective as vitamin D3 in the treatment of rickets but did not demonstrate any therapeutic advantage.
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PMID:Therapeutic and collateral effects of 25-hydroxycholecalciferol in vitamin D deficiency. 2 50

The activity of calcium-stimulated ATPase (E.C. 3.6.1.3) in homogenates of the secretory enamel organ of rat incisors was studied biochemically. ATP hydrolysis was estimated from the amount of inorganic phosphate liberated. An analysis of the total degradation of ATP was initially performed to ensure that the enzyme assays pertained to the original substrate, ATP, and were not influenced by reaction products formed. Standard incubations were run in tris-maleate buffer, pH 8.2, with 3 mM ATP, 3 mM Ca2+ and 0.5 mM R 8231 at 37 degrees C. The presence of R 8231 was necessary to inhibit nonspecific alkaline phosphatase. The calcium-stimulated ATPase was completely inhibited when heated at 55-60 degrees C for 5 min. The pH optimum was found to be 8.2. The hydrolysis was substantially dependent on Ca2+ and was fastest when the ATP:Ca2+ ratio was 1:1. High substrate concentrations inhibited the hydrolysis. The addition of 1 mM Zn2+ and Ni2+ to the incubation medium markedly inhibited the hydrolysis as did, though less strongly, p-hydroxymercuribenzoate, oligomycin, EDTA and ruthenium red. l-Cysteine, mercaptoethanol, iodoacetic acid and sodium azide were without effect. F- was without effect unless added to a final concentration above 15 mM to media where Ca2+ had first been allowed to react with ATP.
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PMID:Calcium-stimulated ATPase activity in homogenates of the secretory enamel organ in the rat. 2 89

A child with hypophosphatemic vitamin D-resistant rickets was treated for three years with the conventional vitamin D-inorganic phosphate supplementation followed by a new therapeutic regimen consisting of 1,25 dihydroxyvitamin D3 (1,25 (OH)2D3) and half of the previous phosphate supplementation. The effectiveness of the two treatment regimens was compared by calcium, phosphate, and magnesium balance techniques and by serial radiological examinations as well as careful height measurements. In addition, the lowering of the urinary pH with ascorbic acid supplementation seems to be associated with improvement in the renal tubular reabsorption of phosphate, but its distinct effect, separate from the rest of the treatment modalities, was not tested in this study. The conventional treatment did not correct the hypophosphatemia and alkaline phosphatase elevation, whereas the 1,25 (OH)2 D3-inorganic phosphate regimen is well tolerated and effective in achieving a sustained normalization of these variables. In addition, the improved growth and healing of rickets further attest to the efficacy of the new treatment.
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PMID:Hypophosphatemic vitamin D-resistant rickets: metabolic balance studies in a child receiving 1,25 dihydroxyvitamin D3, phosphate, and ascorbic acid. 2 11


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