Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: HUMANGGP:019083 (5'-nucleotidase)
 3,019 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Membrane-bound adenosinetriphosphatase (ATPase) activities of the sarcolemma-enriched fraction from bovine aorta were characterized. The membranes, isolated by a sucrose density gradient method, were enriched about 31-fold in sodium- and potassium-stimulated, magnesium-dependent ATPase (Na,K-ATPase) activity, and about 8-fold in 5'-nucleotidase activity compared to the homogenate, suggesting that the isolated membranes were substantially enriched with the sarcolemma. The membranes exhibited about 31, 33 and 42 mumol Pi/mg protein/h of Na,K-ATPase, magnesium-dependent ATPase and calcium-dependent ATPase activities, respectively, in the presence of 4 mmol/l ATP. The sarcolemma-enriched membranes required considerably high concentrations of well-known inhibitors for Na,K-ATPase such as vanadate (more than 1 mumol/l), lanthanum (more than 1 mmol/l) and calcium (10 mmol/l), to induce a significant inhibition in the Na,K-ATPase activity. Treatments of the membrane with physical disruptions and sodium dodecyl sulfate or deoxycholate reduced the total Na,K-ATPase activity, and did not expose fully the ouabain sensitivity of the Na,K-ATPase. These results indicate that there are marked differences in the properties of the ATPase between vascular smooth muscle sarcolemma and cardiac sarcolemma.
 ...
PMID:Characterization of membrane-bound adenosinetriphosphatase activity of sarcolemma-enriched fraction from vascular smooth muscle. 300 74

Intact synaptosomes isolated from the electric organ of the electric ray Torpedo marmorata contain, at their surface, enzyme activities for the hydrolysis of externally applied nucleoside phosphates. The diazonium salt of sulfanilic acid, as a low-molecular-weight, slowly permeating, covalent inhibitory agent, selectively blocks these enzyme activities and leaves intracellular lactate dehydrogenase intact. The ectoenzymes comprise both a nucleoside triphosphate and diphosphate phosphohydrolase, as well as a 5'-nucleotidase. Activity of nonspecific ectophosphatases is absent. The nucleoside triphosphatase hydrolyzes almost equally well ATP, GTP, CTP, UTP, and ITP and is activated to a similar degree by Mg2+ or Ca2+. It has a high affinity for ATP (Km for ATP in the presence of Mg2+, 75 microM; in the presence of Ca2+, 66 microM). Maximal rates in the presence of Mg2+ and Ca2+ were very similar (34.8 and 32.5 nmol of Pi/min/mg of synaptosomal protein, respectively). Either Mg-ATP or Ca-ATP can act as a true substrate. ADP inhibits hydrolysis of ATP, but AMP is without effect. The nucleoside triphosphatase is not inhibited significantly by a number of inhibitors of mitochondrial Mg2+-ATPase or of Ca2+ + Mg2+-ATPases. It is, however, considerably inhibited by filipin and quercitin. The capacity of intact synaptosomes to hydrolyze also extracellular ADP, GDP, AMP, GMP, and IMP suggests that the nucleoside triphosphatase is part of an enzyme chain that causes complete hydrolysis of the respective nucleoside triphosphate to the nucleoside. We conclude that the cholinergic nerve terminals of the Torpedo electric organ can hydrolyze ATP released on coexocytosis with acetylcholine via an ectonucleoside triphosphatase activity that is different from known endogenous nerve terminal ATPases. The final product of the hydrolysis, adenosine, can then be salvaged by the nerve terminal for resynthesis of ATP. Other possible physiological functions of the ectonucleotidases are discussed.
 ...
PMID:Ectonucleotidase activities associated with cholinergic synaptosomes isolated from Torpedo electric organ. 301 88

An accelerated method is developed for isolating a fraction of plasma membranes of pig myometrium using ultracentrifugation within the sucrose density gradient (15% and 30%). The membranes possessed the high activity of 5'-nucleotidase and Na+, K+-ATPase and the low activity of rhotenon-insensitive NADH-cytochrome c reductase. The vesicularized preparations of plasma membranes are able of ATP-dependent accumulation of Ca2+ (7.5 +/- 0.3 nmol. 45Ca2+ per 1 mg of protein for 15 min). Phosphate increases the calcium accumulation in the presence of ATP and Mg2+. Ionophore A 23187 promotes a complete and rapid release of the previously active-accumulated calcium. The release of 45Ca2+ accumulated by the membrane fraction may be reached by introduction of 1 mM EGTA or DS-Na into the incubation medium, that evidences for the cation accumulation inside closed structures. Using concanavalin-A-sepharose 4B it is shown that 60% of membrane vesicles are turned inside out. The low saponine concentrations (0.0005%) which inhibit Ca2+-accumulation by plasma membranes but not by the endoplasmic reticulum inhibit this process by 60-70% in preparations of the isolated membrane fraction. The method has certain advantages over the previously applied methods used for isolating of plasma membrane fragments from smooth muscles.
 ...
PMID:[Isolation and characteristics of the plasma membrane fraction from the swine myometrium]. 301 62

12 sheep and 4 goats were used to detect the presence of alkaline phosphatase (A.P.) and 5'-nucleotidase (5'-N) enzymes in the carotid rete-cavernous sinus structure. Different methods of preservation were used. The calcium and the lead methods were used to detect the presence of A.P. and 5'-N, respectively. Best results in their detection were obtained with liquid nitrogen preservation. A.P. enzyme was found in and around areas in which blood capillaries were present, indicating active transport of materials through the capillary membrane. Slight enzymatic activity was seen on the endothelial surface of the rete branches, while the enzyme seemed to be absent from the cavernous sinus. 5'-N was discernible in the tunica adventitia and in the endothelial cells, while the tunica media of the rete branches was apparently devoid of this enzyme. Possible role of these enzymes in the vascular wall metabolism of this structure has been discussed.
 ...
PMID:Alkaline phosphatase and 5'-nucleotidase enzymes in the carotid rete-cavernous sinus complex of sheep and goats. 302 25

Effects of hypothyroidism on heart sarcolemmal activities were examined by using membrane preparations obtained by two different methods from rats treated with propylthiouracil for 6 to 8 weeks. ATP-independent Ca2+ binding, sialic acid and phospholipid content, Ca2+ ATPase, Mg2+ ATPase and adenylate-cyclase were not altered in membranes isolated by the hypotonic shock-LiBr treatment method from hypothyroid hearts. On the other hand, depressed activities of ouabain sensitive Na+-K+ ATPase and 5'-nucleotidase were observed in this hypothyroid preparation. Sarcolemma isolated by the sucrose density gradient procedure from hypothyroid hearts exhibited lower ouabain-sensitive Na+-K+ ATPase and higher ATP-dependent Ca2+ binding as well as Ca2+ stimulated ATPase without any changes in the 5'-nucleotidase, adenylate cyclase and Mg2+-ATPase activities. The activation of ATP-dependent Ca2+ binding and Ca2+ stimulated ATPase by calmodulin in the hypothyroid preparation was greater than the control; these effects of calmodulin were blocked by trifluoperazine. The results suggest some specific changes in the heart sarcolemmal Ca2+-pump during the development of hypothyroidism.
 ...
PMID:Sarcolemmal Ca2+-binding and enzyme activities in myocardium from hypothyroid rat. 302 94

The effects of the phenothiazine, Stelazine, on Hymenolepis diminuta were investigated. The cestode was incubated for 10 min at 37 degrees C with 1 mM trifluoperazine, in the presence and absence of Ca2+. Assay of brush border enzymes showed that drug treatment lowered the activities of alkaline phosphatase, Ca2+-ATP'ase, 5'-nucleotidase and type 1 phosphodiesterase. This occurred in parallel with a significant reduction in tegumental protein. Under these conditions gross changes in ultrastructural appearance and cellular organization were observed. There was a lack of ordered microtriches and the distal cytoplasm was absent. Glycogen granules were scattered throughout the cytoplasm within the subtegumental layer. The connective tissue also appeared to be in some disarray. The effects of Stelazine appeared to be dependent on time and were significantly increased when Ca2+ was included in the incubation medium. Incubation with the less hydrophobic phenothiazine trifluoperazine sulphoxide had minimal effect on the integrity of the cestode. The results reported here support the premise that certain phenothiazines may be considered as potential cestocidal agents.
 ...
PMID:Biochemical and ultrastructural investigation of the effect of Stelazine (trifluoperazine) on Hymenolepis diminuta (Cestoda). 302 50

Ectoenzyme release from porcine intestinal brush border membranes by phosphatidylinositol-specific phospholipase C of Bacillus thuringiensis was studied. Alkaline phosphodiesterase I, alkaline phosphatase and 5'-nucleotidase were released from both slices and brush border membranes. The pattern of alkaline phosphodiesterase I release was the same as that of alkaline phosphatase. The release of alkaline phosphodiesterase I induced by phospholipase C was dependent on, or proportional to, the reaction time and the concentration of phospholipase C. The Arrhenius plot for phosphodiesterase I release showed a single break at 30 degrees C for brush border membranes. Only 40% of alkaline phosphodiesterase I present in the brush border membranes were solubilized by phosphatidylinositol-specific phospholipase C treatment. The data indicate the presence of two forms of phosphodiesterase I, which are different in their sensitivity to phospholipase C. The released alkaline phosphodiesterase I had a molecular weight of 240,000 and was activated by Mg2+ and Ca2+, but strongly inhibited by EDTA.
 ...
PMID:Alkaline phosphodiesterase I release from eucaryotic plasma membranes by phosphatidylinositol-specific phospholipase C. II. The release from brush border membranes of porcine intestine. 302

To investigate whether slow Ca2+ channel blockers protect against development of changes in properties of the sarcolemma and in the tissue ultrastructure during myocardial ischemia, nifedipine was administered prior to occlusion (up to 3 hours) of the left anterior descending coronary artery in anesthetized pigs. Intravenous doses which reduced arterial blood pressure by 20-25%, had no effect on the time-dependent reduction of Ca2+-calmodulin and cyclic AMP-dependent 32P incorporation into sarcolemmal phospholamban-like protein. Nifedipine blocked the reduction in the activity of sarcolemmal 5'-nucleotidase. Nifedipine had no significant effect on the long-chain fatty acylcarnitine accumulation in sarcolemma. A marked delay in the appearance of ultrastructural indicators of irreversible tissue injury in subepicardial myocardium was observed, when nifedipine was infused. Particularly the reduced appearance of electron-dense bodies in mitochondria suggested a reducing effect of nifedipine on cellular net gain of Ca2+. Apparently, ischemia-induced loss of the ability of the proteinkinases to incorporate phosphate into sarcolemmal phospholamban-like protein is not a process secondary to Ca2+ overload of the myocardium. The involvement of accumulation of long-chain fatty acylcarnitine within the sarcolemma may also be excluded. The membrane defect as indicated by a change in phosphorylation-mediated control of Ca2+ transport may itself be associated with the development of ischemia (-reperfusion)-induced Ca2+ overload.
 ...
PMID:The effect of nifedipine on ischemia-induced changes in the biochemical properties of isolated sarcolemmal vesicles and the ultrastructure of myocardium. 303 May 20

Cholesteryl esterase activities were determined in homogenates of rat heart (ventricles), isolated, calcium-tolerant, cardiac myocytes and aortic tissue and were compared with acid and neutral triglyceride lipase activities in these fractions. Using cholesteryl oleate/phosphatidylcholine/taurocholate emulsions and digitonin pretreatment of the enzyme fractions, acid and neutral cholesteryl esterase activities were measured in all tissue preparations. In contrast to the acid and neutral triglyceridase and acid cholesteryl esterase activity, the neutral cholesteryl esterase activity was subject to substrate inhibition. Upon isolation of cardiac myocytes, and in contrast with the recovery of neutral triglyceride lipase activity, only a small portion of the neutral cholesteryl esterase (6%) was recovered, suggesting that nonmyocyte neutral cholesteryl esterase activity markedly contributes to the relatively high activity detectable in whole ventricular homogenates. The recovery of large amounts of neutral cholesteryl esterase activity in the supernatant of collagenase-digested heart tissue, obtained during the isolation of myocytes, which is also markedly enriched in activities of two endothelial marker enzymes (5'-nucleotidase and angiotensine-converting enzyme) may indicate the predominant contribution of neutral cholesteryl esterase activity from coronary endothelial cells to this activity detectable in ventricular homogenates. Relative to the activity in ventricular and myocyte homogenates, aorta homogenates possessed the highest specific neutral cholesteryl esterase activity. We propose that in addition to coronary endothelium, smooth muscle cells also contribute to the neutral cholesteryl esterase activity in ventricular homogenates.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Cholesteryl esterase activities in ventricles, isolated heart cells and aorta of the rat. 303 10

The effect upon human chorionic gonadotropin (hCG) binding of a 90-min incubation of plasma membranes prepared from the corpora lutea of control and prostaglandin F2 alpha injected rats was studied. After incubation for 90 min with 1 mM CaCl2 at 40 degrees C, single point hCG binding assays at room temperature revealed a significant decrease in the degree of binding of approximately 50% in membrane samples prepared from regressed corpora lutea. The binding decrease in regressed samples did not occur if the incubation temperature was reduced to 35 degrees C or if calcium ion was replaced with magnesium. Scatchard analyses indicated that the decrease in binding capacity was the result of a loss of gonadotropin receptors rather than an affinity shift. Specific activities of two membrane-bound enzymes (Na+-K+ ATPase, 5'-nucleotidase) did not change in a correlative fashion during the incubation. In previous studies the same in vitro conditions caused a substantial and significant decrease in membrane fluidity, as determined by fluorescence polarization. Thus it appears that the membrane rigidification is of a specific nature and interferes with gonadotropin binding during luteolysis.
 ...
PMID:Impairment of gonadotropin binding occurs during membrane rigidification in plasma membrane samples prepared from regressed rat corpora lutea. 316 13


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>