Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.3.5 (5'-nucleotidase)
 3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activity of guanine deaminase (GAH, E.C.3.5.4.3) was lower in rat cerebellum soluble and microsomal fractions than in rat brain subfractions. Adenosine deaminase (ADA, E.C.3.5.4.4) activity was released in higher proportion than guanine deaminase, purine nucleoside phosphorylase (PNP, E.C.2.1.2.4), 5'-nucleotidase (5'N, E.C.3.1.3.5), and lactate (LDH, E.C. 1.1.1.27) and malate (MDH, E.C. 1.1.1.37) dehydrogenase in press-juices of rat brain. Furthermore, nerve ending-derived fractions (synaptosomes and synaptic vesicles) showed an enrichment of adenosine deaminase and also of 5'-nucleotidase. The action of deoxycholate over the subfractions did not increase the activity of either enzyme. The contrary occurred with the remaining enzymes studied. Thus, it is possible that one set of enzymes are located on the surface of the particulate vesicles, whereas another set are located inside these vesicles, suggesting a compartmentation of purine catabolic enzymes in different areas of the central nervous system.
 ...
PMID:Heterogeneous localization of some purine enzymes in subcellular fractions of rat brain and cerebellum. 301 Jan 50

The subcellular distribution of the 5'-nucleotidase activity was investigated in normal and hypertrophied pig hearts; normal rat hearts were used for comparison. The left ventricular hypertrophy was induced in pigs by banding the supravalvular aorta for 4, 8 and 12 weeks. By employing different procedures for the isolation of cardiac membranes, a major catalytic site for 5'-nucleotidase was found to be located at sarcolemma in rat heart and microsomes (sarcoplasmic reticulum) in pig heart. A progressive decrease in the homogenate and microsomal 5'-nucleotidase activity occurred upon the development of myocardial hypertrophy in pigs. This reduction in microsomal 5'-nucleotidase activity was characterized by a depression in both apparent Vmax and Km values. These results indicate that a primary 5'-nucleotidase pool is present in the intracellular compartment of the pig heart and is altered during the development of hypertrophy.
 ...
PMID:Subcellular distribution of cardiac 5'-nucleotidase: alteration of microsomal pool in hypertrophied pig heart. 301 68

The transmembrane topography of the rat hepatocyte ectoenzyme 5'-nucleotidase was studied by the use of glycoprotein labelling and limited-proteolysis techniques. Comparison, by one-dimensional peptide mapping, of enzyme iodinated from outside the cell with that iodinated in the solubilized state showed that no additional iodination sites were revealed on solubilization. Incubation of newly synthesized enzyme in a microsomal membrane fraction with proteinase showed that the entire molecule of 5'-nucleotidase was protected from proteolysis. These data suggest that little, if any, of the 5'-nucleotidase molecule is present on the cytoplasmic side of the plasma membrane. No evidence was found for a previously proposed interaction between 5'-nucleotidase and actin, although the ability of preparations of 5'-nucleotidase to prevent inhibition of deoxyribonuclease I by actin was explained by minute traces of ATPase activity. Comparison of peptide maps of enzyme labelled by iodination or by methods specific for carbohydrate showed that in both cases predominantly one section of the molecule was labelled. It is proposed that the enzyme is a short-stalked integral membrane protein without a cytoplasmic domain in which about one-third of the molecule forms the accessible molecular surface.
 ...
PMID:The membrane topography of ecto-5'-nucleotidase in rat hepatocytes. 301 17

5'-Nucleotidase was assayed in the membrane fractions isolated from rabbit lung homogenate. The enzyme activity was measured from the rate of hydrolysis of [U-14C]cytidine 5'-monophosphate (CMP). The optimal pH of the rate of hydrolysis is around 8.0 and the enzyme activity is stimulated by Mg2+. The apparent Km and Vmax of the enzyme in the microsomal fraction for CMP were 3.33 mM and 1.43 mumol/min/mg protein, respectively. During lung development the enzyme activity increased moderately at late gestational ages and reached its maximum level in adults (p less than 0.001). The developing profile of 5'-nucleotidase activity is similar to the developing pattern of the CMP content in rabbit lungs.
 ...
PMID:5'-Nucleotidase activity in adult and fetal rabbit lungs. 301 38

Chronic feeding of male Wistar rats with food containing hexachlorobenzene (HCB) at 17.5 mmol/kg induced elevation of serum amino-transferases and bilirubin content, increase of microsomal cytochrome P-450 concentration, and decrease of 5'-nucleotidase, K+,Na+- and Mg2+-adenosine triphosphatase activities in liver plasma membrane preparations. These changes were potentiated by ethanol consumption suggesting a possible role of liver plasma membrane damage in the pathogenesis of HCB intoxication.
 ...
PMID:Rat liver plasma membrane damage in hexachlorobenzene intoxication and its potentiation by ethanol. 302 30

The distribution of plasma membrane markers, the sodium pump [evaluated as ouabain-sensitive, potassium-stimulated p-nitrophenyl phosphatase (K+-pNPPase)], [3H]saxitoxin binding, and 5'-AMPase, was studied in the subcellular fractions prepared from the homogenates of the longitudinal smooth muscle/myenteric plexus of dog ileum. The K+-pNPPase activity and [3H]-saxitoxin binding were found to be predominantly associated with the synaptosomal fraction as indicated by the high level of these activities in the crude synaptosomal fraction and by the copurification of K+-pNPPase and [3H]saxitoxin binding, but not 5'-AMPase, with several synaptosomal markers during the fractionation of the crude synaptosomal fraction on density gradients. In contrast to the K+-pNPPase activity and [3H]saxitoxin binding, the 5'-AMPase activity was found to be concentrated in the microsomal pellet. Further fractionation of microsomes on density gradient resulted in copurification of 5'-AMPase but not K+-pNPPase or [3H]saxitoxin binding, with other smooth muscle plasma membrane-bound enzymes, such as high-affinity Ca2+-ATPase, Mg2+-ATPase, and Ca2+-ATPase. It was concluded that in the longitudinal smooth muscle/myenteric plexus, the sodium pump activity is present in higher density in the neuronal plasma membranes whereas 5'-AMPase activity is concentrated in the smooth muscle plasma membranes.
 ...
PMID:Subcellular fractionation of the longitudinal smooth muscle/myenteric plexus of dog ileum: dissociation of the distribution of two plasma membrane marker enzymes. 304 Sep 6

Homogenisation and fractionation of cells in the presence of Mg2+ or EDTA resulted in unoccupied oestrogen receptor being recovered in the particulate fraction. Nuclei were partially purified by pelleting at 100,000 g through 41% and 44% (w/w) sucrose (in buffer containing Mg2+ or EDTA), plasma membranes being collected from the top of the 41% barrier. In Mg2+-prepared fractions, both 5'-nucleotidase and unoccupied receptor were distributed between plasma membrane, partially-pure nuclei and mitochondrial/microsomal pellets. Lactate dehydrogenase was not a significant contaminant of particulate fractions. In EDTA fractions, the majority of binding activity was in the partially-pure nuclei (which were extensively disrupted) and mitochondrial/microsomal pellets. Little or no binding was found in the EDTA-prepared plasma membranes which were amorphous in appearance. Mg2+-prepared nuclei, freed of membranous contamination by pelleting through 1.8 M sucrose, were intact by electron microscopy but had no 5'-nucleotidase or unoccupied receptor. These data suggest that recovery of receptor in partially-pure nuclei during fractionation is not caused by trapping of cytosolic protein but rather by redistributed nuclear receptor having become bound to adhering plasma membrane fragments during homogenisation. Implications for the study of cell-free systems are discussed.
 ...
PMID:The effects of Mg2+ ions or EDTA on nuclear integrity and apparent subcellular distribution of unoccupied oestrogen receptors in breast cancer cells. 309 86

Male Wistar rats were treated for 3 weeks with alpha-naphthyl isothiocyanate (ANIT, 5.4 mmol per kg food). Chronic necrotic cholangitis without pronounced transaminasemia and hyperbilirubinemia developed. The activity of 5'-nucleotidase in liver plasma membrane preparations was strongly depressed (3.5 times) while the activities of K+-, Na+- and Mg++-ATPases were not affected. The liver microsomal cytochrome P-450 and cytochrome b5 contents decreased. Elevation of reduced glutathione liver content after challenge with ANIT was recorded. The observed biochemical changes may be important for the pathogenesis of ANIT-induced chronic cholangitis.
 ...
PMID:Biochemical changes in alpha-naphthyl isothiocyanate-induced chronic cholangitis in the rat. 322 62

Plasma membrane vesicles isolated from rat liver exhibited an azide-insensitive Mg2+-ATP-dependent Ca2+ pump which accumulated Ca2+ at a rate of 5.1 +/- 0.5 nmol of calcium/mg of protein/min and reached a total accumulation of 33.2 +/- 2.6 nmol of calcium/mg of protein in 20 microM Ca2+ at 37 degrees C. Equiosmotic addition of 50 mM Na+ resulted in a loss of accumulated calcium. Measurement of Mg2+-ATP-dependent Ca2+ uptake in the presence of 50 mM Na+ revealed no effect of Na+ on the initial rate of Ca2+ uptake, but a decrease in the total accumulation. The half-maximal effect of Na+ on Ca2+ accumulation was achieved at 14 mM. The Ca2+ efflux rate constant in the absence of Na+ was 0.16 +/- 0.01 min-1, whereas the efflux rate constant in the presence of 50 mM Na+ was 0.25 +/- 0.02 min-1. Liver homogenate sedimentation fractions from 1,500 to 105,000 X g were assayed for azide-insensitive Mg2+-ATP-dependent Ca2+ accumulation. Na+-sensitive Ca2+ uptake activity was found to specifically co-sediment with the plasma membrane-associated enzymes, 5'-nucleotidase and Na+/K+-ATPase, whereas Na+-insensitive Ca2+ uptake was found to co-sediment with the endoplasmic reticulum-associated enzyme, glucose-6-phosphatase. The plasma membrane Ca2+ pump was also distinguished from the endoplasmic reticulum Ca2+ pump by its sensitivity to inhibition by vanadate. Half-maximal inhibition of plasma membrane Ca2+ uptake occurred at 0.8 microM VO4(3-), whereas half-maximal inhibition of microsomal Ca2+ uptake occurred at 40 microM.
 ...
PMID:Liver plasma membrane calcium transport. Evidence for a Na+-dependent Ca2+ flux. 348 13

A procedure for the purification of the enzyme bile acid:CoA ligase from guinea pig liver microsomes was developed. Activity toward chenodeoxycholate, cholate, deoxycholate, and lithocholate co-purified suggesting that a single enzyme form catalyzes the activation of all four bile acids. Activity toward lithocholate could not be accurately assayed during the earlier stages of purification due to a protein which interfered with the assay. The purified ligase had a specific activity that was 333-fold enriched relative to the microsomal cell fraction. The purification procedure successfully removed several enzymes that could potentially interfere with assay procedures for ligase activity, i.e. ATPase, AMPase, inorganic pyrophosphatase, and bile acid-CoA thiolase. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis the purified ligase gave a single band of approximately 63,000 Mr. A molecular size of 116,000 +/- 4,000 daltons was obtained by radiation inactivation analysis of the ligase in its native microsomal environment, suggesting that the functional unit of the ligase is a dimer. The purified enzyme was extensively delipidated by adsorption to alumina. The delipidated enzyme was extremely unstable but could be partially stabilized by the addition of phospholipid vesicles or detergent. However, such additions did not enhance enzymatic activity. Kinetic analysis revealed that chenodeoxycholate, cholate, deoxycholate, and lithocholate were all relatively good substrates for the purified enzyme. The trihydroxy bile acid cholate was the least efficient substrate due to its relatively low affinity for the enzyme. Bile acid:CoA ligase could also be solubilized from porcine liver microsomes and purified 180-fold by a modification of the above procedure. The final preparation contains three polypeptides as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The three peptides range in size from 50,000 to 59,000, somewhat smaller than the guinea pig enzyme. The functional size of the porcine enzyme in its native microsomal environment was determined by the technique of radiation inactivation analysis to be 108,000 +/- 5,000 daltons. Thus, the functional form of the porcine enzyme also appears to be a dimer.
 ...
PMID:Bile acid: CoASH ligases from guinea pig and porcine liver microsomes. Purification and characterization. 355 96


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