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)

Proximal tubule cells were isolated from swine kidney and cultured for periods of more than 30 days. The cells formed confluent monolayers after plating on a collagen surface and they were passaged more than 5 times on this matrix. The cells maintain several metabolic functions of proximal tubule cells, including gluconeogenesis and the ability to respond to epinephrine and parathyroid hormone. Gluconeogenesis, a principal metabolic pathway in proximal tubule cells, was examined as a function of days in culture. The isolated cells showed a nearly constant rate of gluconeogenesis from 14C-lactate, 14C-alanine and 14C-glycerol with no significant loss of activity for at least 30 days in culture. Likewise, the activities of several cytosolic and membrane associated enzymes including, alkaline phosphatase, delta-glutamyltransferase, fructose-1,6-bisphosphatase and phosphofructokinase were nearly constant over the same time period. The cells responded to treatment with epinephrine and parathyroid hormone, and the rate of gluconeogenesis from 14C-lactate doubled in the presence of these hormones. The morphological and biochemical evidence obtained in these studies show that the proximal tubule cells isolated from swine kidney provide an excellent well defined system for studying the hormonal regulation of carbohydrate metabolism in this tissue.
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PMID:Regulation of gluconeogenesis in swine kidney proximal tubule cells. 277 Jul 16

Organic solvents (ethylene glycol, glycerol, dimethyl sulphoxide, dimethylformamide, dioxane, methanol and propanol-2, as well as sucrose and urea) have been included in aqueous two-phase (liquid-liquid) systems comprised of water, dextran and poly(ethylene glycol). The concentration of the organic solvent was in most cases 20% (w/w). The influence of these solvents on the phase-forming properties, the volume ratio, the freezing point and the partitioning of a polymer-bound ligand, Procion Red HE-3B poly(ethylene glycol), has been studied. The partition coefficients for alkaline phosphatase decrease with ethylene glycol, glycerol, sucrose and urea (factors of 0.25-0.5), but increase with the other substances (factors of 1.2-1.6). The temperature effects on the partitioning of alkaline phosphatase from calf intestine as well as of phosphofructokinase from yeast in systems containing ethylene glycol have been studied and compared with partitioning in standard systems, not containing solvents. The possible uses of the above systems for partitioning studies of enzymes are discussed.
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PMID:Effects of organic solvents on the partitioning of enzymes in aqueous two-phase systems. 295 91

Phosphofructokinase from rat heart perfused with epinephrine was purified to homogeneity and various allosteric properties were determined under conditions which approximate physiological concentrations of the substrates, effectors, and pH. The molecular weights of the protomer of the enzyme isolated from the hormone-stimulated and the control hearts are both approximately 83,000. The epinephrine-stimulated and the control enzymes contain 1.1 and 0.66 mol of phosphate/mol of protomer, respectively. Both enzymes can be fully phosphorylated by cAMP-dependent protein kinase indicating that the phosphorylation site is new and distinct from the known phosphorylation site of skeletal muscle phosphofructokinase. Pure phosphofructokinase isolated from the epinephrine-stimulated heart is significantly less sensitive to inhibition by ATP and citrate, and the K0.5 values for Fru-6-P (0.18 mM) and Fru-2,6-P2 (3 microM) are one-half those for the enzyme from control hearts. In the presence of in vivo concentrations of ATP, citrate, and Fru-6-P at pH 7.1, both enzymes are inactive in the absence of Fru-2,6-P2. Moreover, the K0.5 values for Fru-2,6-P2 of the hormone-stimulated and untreated enzymes are 3 and 6 microM, respectively. These differences in the allosteric properties of phosphofructokinases from the hormone-treated and the control hearts disappear when the enzymes are dephosphorylated by alkaline phosphatase. Determination of the glycolytic intermediates showed a 2-fold increase in Fru-6-P, Fru-2,6-P2, and AMP and 13-fold increase in Fru-1,6-P2. Partially purified Fru-6-P,2-kinase from epinephrine-stimulated and control hearts show KFru-6-P0.5 = 4 and 15 microM, respectively. These results indicate that rat heart phosphofructokinase in vivo requires Fru-2,6-P2 for its activity. Epinephrine stimulates phosphorylation of phosphofructokinase which results in a more active form. The hormone also increases Fru-2,6-P2 which appears to be the result of an activation of Fru-6-P,2-kinase by a covalent modification.
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PMID:Regulation of phosphofructokinase in perfused rat heart. Requirement for fructose 2,6-bisphosphate and a covalent modification. 316 Jul 3

This communication presents the results obtained in tubular aggregates of 24 enzyme histochemical techniques for demonstrating activity of oxidoreductases, transferases, hydrolases and isomerases. The activity characteristics of the tubular aggregates in m. gluteus medius of 18 patients with diseases of the neuromuscular system were almost identical. A high activity of the mitochondrial enzymes, NADPH: tetrazolium oxidoreductase, NADH:tetrazolium oxidoreductase and cytochrome c oxidase, could be shown in the pathological structures, whereas the activity of the mitochondrial enzymes, glycerol-3-phosphate:menadione oxidoreductase, succinate:PMS oxidoreductase, malate:NAD+ oxidoreductase and isocitrate:NAD+ oxidoreductase, and the partial mitochondrial enzymes, malate:NADP+ oxidoreductase and isocitrate:NADP+ oxidoreductase, was very slight or even absent. There was a moderate to strong activity of the glycolytic enzymes lactate:NAD+ oxidoreductase, glyceraldehyde-3-phosphate:NAD+ oxidoreductase, phosphofructokinase, phosphoglucomutase and glucose phosphate isomerase. In contrast, the activity of alpha-glucan phosphorylase was slight. The activity of phosphogluconate:NADP+ oxidoreductase, glucose-6-phosphate:NADP+ oxidoreductase and 5'-nucleotidase was slight, whereas there was no activity of myosin ATPase and mitochondrial ATPase, acid phosphatase or alkaline phosphatase. The high activity of AMP-deaminase was very striking. The activity of peroxidase was moderate. Results obtained with adsorption studies point to adsorption of some of the enzymes studied to the tubular aggregates in vivo and this phenomenon very probably determined the histochemical characteristics of these structures.
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PMID:Histochemical features of tubular aggregates in diseased human skeletal muscle fibres. 317 98

Ancylostoma ceylanicum infection in golden hamsters (Mesocricetus auratus) caused marked biochemical and histopathological derangements. Jejunum, the primary site of infection, showed pronounced alterations compared with liver. Though the biochemical composition of jejunum was not significantly altered, activities of a few lysosomal enzymes were enhanced during hookworm infection. Marked damage to mitochondrial and microsomal membranes was reflected in changes in the activities of the marker enzymes from jejunal tissue. Lipid content, especially phospholipids and neutral lipids of hepatic tissue, exhibited marked elevation. Levels of hexokinase, phosphofructokinase, and lactate dehydrogenase were enhanced in jejunal as well as hepatic tissues, indicating activation of the glycolytic machinery during hookworm infection. A decrease in the levels of mucosal disaccharidases indicated damage to intestinal brush border membranes. However, alkaline phosphatase activity was increased in intestinal mucosa during the infection. Light microscopic examination of jejunal tissue revealed peeling off of the upper epithelial layer, activation of the goblet cells, and thickening of muscularis mucosa. However, hepatic tissue did not show gross alterations, except for slight necrosis in the centrilobular region.
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PMID:Biochemical and histopathological alterations in golden hamster during infection with Ancylostoma ceylanicum. 339 68

Rabbit morulae were grown for 24 h in Ham's F12 medium supplemented with BSA. CI-628 citrate (1.5 micrograms/ml), a specific oestrogen antagonist, significantly inhibited the transformation of morulae to blastocysts. This inhibition was reversed with oestradiol-17 beta (1 micrograms/ml) but not oestradiol-17 alpha (1 micrograms/ml) added to the culture medium. The specific activities of phosphofructokinase, lactic dehydrogenase, malate dehydrogenase and alkaline phosphatase in blastocysts grown in vitro for 24 h in medium TC 199 + BSA showed significant elevation with blastocyst growth and expansion, while that of acid phosphatase revealed no change, and leucine aminopeptidase activity declined significantly. These changes were markedly inhibited by CI-628 citrate (2 micrograms/ml) and were reversed by oestradiol-17 beta (0.4 micrograms/ml) but not by oestradiol-17 alpha (0.4 micrograms/ml). Our findings suggest a role of oestrogen present in the rabbit morula and blastocyst in the triggering of embryonic differentiation and metabolic functions.
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PMID:Role of embryonic oestrogen in rabbit blastocyst development and metabolism. 623 Apr 43

Conditions are described for the preparation of permeabilized cells of Candida albicans. This method has been used for the in situ assay of enzymes in both yeast cells and germ-tube forming cells. A mixture of toluene/ethanol/Triton X-100 (1:4:0.2, by vol.) at 15% (v/v) and 8% (v/v) was optimal for the in situ assay of glucose-6-phosphate dehydrogenase in yeast and germ-tube forming cells, respectively. The concentration of toluene/ethanol/Triton X-100 required for optimal in situ activity of other enzymes was influenced by the cellular location of the enzyme, growth phase and morphology. The membrane-bound enzymes (chitin synthase, glucan synthase, ATPase), cytosolic enzymes (glucose-6-phosphate dehydrogenase, isocitrate dehydrogenase, pyruvate kinase, phosphofructokinase, alkaline phosphatase, glucosamine-6-phosphate deaminase and N-acetylglucosamine kinase) and wall enzymes (beta-glucosidase and acid phosphatase) were measured and compared to the activity obtained in cell extracts. The pattern of enzyme induction and the properties of the allosteric enzymes phosphofructokinase and pyruvate kinase were measured in situ. Pyruvate kinase in situ was homotropic for phosphoenolpyruvate with a Hill coefficient of 1.9 and a S0.5 of 0.6 mM, whereas in cell extracts, it had a Hill coefficient of 1.9 and a S0.5 of 1.0 mM. The Km for ATP was 1.6 mM in cell extracts and 1.8 mM in permeabilized cells. In situ phosphofructokinase was homotropic for fructose 6-phosphate (S0.5 of 2.3 mM, Hill coefficient of 4.0). The kinetic properties of pyruvate kinase and phosphofructokinase measured in situ or in vitro were similar for both yeast cells and germ-tube forming cells.
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PMID:The in situ assay of Candida albicans enzymes during yeast growth and germ-tube formation. 631 58

The "activation factor" for phosphofructokinase was shown by chemical analysis, by synthesis, and by 13C NMR spectroscopy to be beta-D-fructose-2,6-P2. This compound was prepared from D-fructose-1,2-cyclic 6-P2 by alkaline hydrolysis. D-Fructose-1,2-cyclic 6-P2 is ineffective in activating phosphofructokinase while synthetic D-fructose-2,6-P2 has the same specific activity toward phosphofructokinase as the "activation factor" isolated from rat liver, and it exhibits the same characteristics on paper and ion exchange chromatography. Acid treatment of both the synthetic and the natural product destroys the biological activity and yields 1 mol each of fructose-6-P and Pi; alkaline phosphatase treatment of the compound followed with acid hydrolysis yields fructose. The natural abundance 13C NMR spectra of the synthetically prepared and purified D-fructose-1,2-cyclic 6-P2 and D-fructose-2,6-P2 have been obtained and all resonances have been assigned. The spectra also show that both samples contain predominantly one anomer and the 13C chemical shifts and 31P-13C coupling constants are consistent only with the beta-anomer.
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PMID:The structure of "activation factor" for phosphofructokinase. 645 27

Phosphofructokinase activity is modulated by allosteric effectors and macromolecular interactions (e.g. binding to myofibrillar components). The aim of this study was to determine the effects of ATP and bisphosphorylated sugars upon phosphofructokinase in the presence of myofibrils. Myofibrils were prepared from resting and electrically stimulated rat muscle. Dephosphorylation of myofibrils was performed with alkaline phosphatase acid. Purified rabbit skeletal muscle phosphofructokinase was used for all experiments. Myofibrils from resting muscle showed a higher capacity to bind phosphofructokinase and a lower phosphate content than myofibrils from stimulated muscle. Dephosphorylation of myofibrils did not increase their binding capacity. Myofibrils greatly counteracted the inhibition of phosphofructokinase by high concentrations of ATP, without affecting maximum activity. In the presence of myofibrils, both glucose 1,6-bisphosphate and fructose 2,6-bisphosphate additionally activated muscle phosphofructokinase. We suggest that the binding of phosphofructokinase to myofibrils in combination with increasing glucose 1,6-bisphosphate concentration could be important in the enhancement of the glycolytic flux that takes place during muscle contraction.
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PMID:Myofibril-bound muscle phosphofructokinase is less sensitive to inhibition by ATP than the free enzyme, but retains its sensitivity to stimulation by bisphosphorylated hexoses. 893 Jan 43

White New Zealand male rabbits were fed a high-cholesterol (1%) diet for 7 weeks. The activity of alkaline phosphatase (AP), alanine (AlaAT), aspartate (AspAT) aminotransferases and level of glucose in the blood plasma of rabbits was determined and compared with those of a control group of animals. The cholesterol-enriched diet resulted in increases in plasma AlaAT and AP activity and a decrease in plasma glucose. In the liver, cholesterol treatment decreased the activity of AspAT, AlaAT, AP, phosphoglucomutase, phosphofructokinase, pyruvate kinase and lactate dehydrogenase. Activities of glucosephosphate isomerase, aldolase and the level of glycogen were not affected. No statistically significant changes in the activity of examined enzymes in heart of rabbits fed with cholesterol-enriched diet were observed. Chronic intake of cholesterol in the diet had a negative effect on liver metabolism but not on heart metabolism in rabbits.
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PMID:Effect of cholesterol-enriched diet on liver and heart enzymes in male rabbits. 946 63


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