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:3.1.3.5 (5'-nucleotidase)
3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Large numbers of taste buds are distributed over the body surface of the channel catfish ictalurus punctatus, with the barbels having an especially high density. L-Alanine, as well as certain other amino acids, are taste stimuli in this animal. Epithelial tissue obtained by gentle scraping of the barbel surface was fractionated by differential centrifugation. A sedimentable fraction (P2) was prepared that was enriched in L[OH]alanine binding activity, the plasma membrane marker enzyme 5'-nucleotidase, and the mitochondrial marker succinate cytochrome c reductase, but not the microsomal marker NADH cytochrome c redu.ctase. Binding of L-[OH]alanine was measured using a Millipore filter method in which correction for non-specific binding was also determined. Time, temperature, and pH for measuring binding activity were established. At the optimal pH of 7.8, the KD for L-alanine is 4.8 X 10(-6) M. The first order dissociation rate constant at 6 degrees is 3.8 X 10(-4) s-1 and at 24 degrees it is 12.1 X 10(-4) s-1. The second order rate constant for association is between 10(2) and 10(3) M-1 S-1. Reversibility of the binding interaction was also demonstrates by the rapid displacement of bound L-[3H]alanine by a large excess of unlabeled L-alanine. That the binding does not represent incorporation into protein was confirmed by the lack of effect of puromycin. The amounts bound of several other chemostimulatory amino acids werealso determined.
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PMID:Biochemical studies of tast sensation. Binding of L-[3H]alanine to a sedimentable fraction from catfish barbel epithelium. 0 Apr 3

Human placental microsomal 5'-nucleotidase (EC 3.1.3.5) was prepared free of alkaline phosphatase by isoelectric focusing. A total of seven electrophoretic variants were isolated during the preparation of six placentas. Only three to six variants were found in a single placenta. The isoelectric pH's were 6.70, 6.44, 6.23, 6.02, 5.76, 5.63 and 5.44. These were found to be composed of variable quantities of a large, medium and low molecular weight form. The apparent molecular weights of the medium and light form of the enzyme were 86 500 and 43 500, respectively, as estimated from Stokes radius and sedimentation velocity determinations. The electrophoretic variants were not distinguishable with respect to specific activity and Michaelis constants for AMP, GMP or CMP or inhibition by ATP, CTP or adenosine. These electrophoretic variants appeared to be pseudoisozymes based upon different states of aggregation of a common primary sequence. There was a wide range of substrate specificity among nucleoside 5'-monophosphates which included 2-deoxyribose compounds. With AMP as 100, substrate activity was: CMP, 122; NMN, 74; GMP, 68: IMP, 63; XMP, 28 and UDP-glucose, 68. The Michaelis constants for AMP, GMP and CMP ranged from 12-18 muM, from 33-67 muM and from 170-250 muM, respectively. Although 5'-nucleotidase was active in the absence of divalent cation, 5 mM MgCl2 stimulated the enzyme activity to 234% of control and shifted the pH optimum of 9.8 to a plateau from pH 7.4-9.8.
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PMID:Purine catabolism in man: characterization of placental microsomal 5'-nucleotidase. 0 35

1. Highly sensitive technique are described for the assay of plasma membrane (5'-nucleotidase, alkaline phosphatase), microsomal (neutral alpha-glucosidase, leucyl-2-naphthylamidase) and biliary canalicular (gamma-glutamyltransferase) enzymes and for nine acid hydrolases (acid phosphatase, phosphodiesterase, beta-glucosidase, alpha-glucosidase, alpha-galactosidase, beta-galactosidase, alpha-mannosidase, N-acetyl-beta-glucosaminidase, beta-glucuronidase) in human liver. 2. Optimum and specific assay systems have been developed which give linear kinetics for all enzymes. 3. The range of enzyme activities in samples of human liver, obtained by closed needle biopsy, and sera have been determined.
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PMID:Enzyme activities in human liver biopsies: assay methods and activities of some lysosomal and membrane-bound enzymes in control tissue and serum. 1 4

The levels of serum gamma-glutamyl transpeptidase (GGT) and, when appropriate, alkaline phosphatase (AP) and 5'-nucleotidase (NTD) have been measured as a routine in 276 patients with malignant haematological diseases during a 26-month trial period. GGT levels add no prognostic information to the routine haematological surveillance of leukaemia. Polychemotherapy does not appear to be an inducer of liver drug-metabolising microsomal enzymes. Polycythaemia rubra vera, myelofibrosis and chronic lymphocytic leukaemia may cause little change in GGT, AP and NTD levels despite marked hepatomegaly. A raised GGT in Hodgkin's disease and non-Hodgkin lymphoma is generally associated with active and widespread disease, but not necessarily a sign of malignant tissue in the liver. The elevations of GGT in myeloma may be secondary to liver infiltration though this group merits further detailed study.
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PMID:Evaluation of the usefulness of serum gamma-glutamyl transpeptidase levels in the management of haematological neoplasia. 2 19

The localization of alkaline phosphatase in HeLa cells was examined by electron microscopic histochemistry and subcellular fractionation techniques. Two monophenotypic sublines of HeLa cells which respectively produced Regan and non-Regan isoenzymes of alkaline phosphatase were used for this study. The electron microscopic histochemical results showed that in both sublines the major location of alkaline phosphatase is in the plasma membrane. The enzyme reaction was occasionally observed in some of the dense body lysosomes. This result was supported by data obtained from a subcellular fractionation study which showed that the microsomal fraction rich in plasma membrane fragments had the highest activity of alkaline phosphatase. The distribution of this enzyme among the subcellular fractions closely paralleled that of the 5'-nucleotidase, a plasma membrane marker enzyme. Characterization of the alkaline phosphatase present in each subcellular fraction showed identical enzyme properties, which suggests that a single isoenzyme exists among fractions obtained from each cell line. The results, therefore, confirm the reports suggesting that plasma membrane is the major site of alkaline phosphatase localization in HeLa cells. The absence of any enzyme reaction in the perimitochondrial space in these cultured tumor cells also indicates that the mitochondrial localization of the Regan isoenzyme reported in ovarian cancer may not be a common phenomenon in Regan-producing cancer cells.
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PMID:Plasma membrane localization of alkaline phosphatase in HeLa cells. 5 27

Membrane glycoproteins have been studied in the normal lactating mammary gland and R3230 AC mammary tumor of the rat. Plasma membrane-enriched fractions were obtained from these tissues by discontinuous sucrose gradient centrifugation of a microsomal preparation from the tissue homogenates. The lightest membrane fractions (F-1 and F-2) have the greatest enrichment of plasma membrane markers, with a 14- to 20-fold purification of 5'-nucleotidase and Na+-K+ -adenosine triphosphatase over the homogenate values in both tumor and normal tissues for F-1. Electron microscopy shows smooth membrane vesicles for these fractions. Polypeptide analysis by acrylamide gel electrophoresis shows essentially the same patterns for F-1 and F-2 and only relatively minor differences between membrane components of tumor and normal tissues. Glycoprotein analysis of the polyacrylamide gels by periodate-Schiff staining indicates more dramatic differences. Membrane Fraction F-1 from normal tissue contains two major glycoproteins, GP-II and GP-III, while Fractions F-2 and F-3 contain an additional glycoprotein, GP-I, with a higher apparent molecular weight. In the tumor, the component corresponding to GP-III is decreased or absent and a new component GP-IV is seen at a lower apparent molecular weight.
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PMID:Membrane glycoprotein differences between normal lactating mammary tissue and the R3230 AC mammary tumor. 12 79

The ionic influence and ouabain sensitivity of lymphocyte mg-2+-atpase and Mg-2+-(Na+ +K+)-activated ATPase were studied in intact cells, microsomal fraction and isolated plasma membranes. The active site of 5'-nucleotidase and Mg2+-ATPase seemed to be localized on the external side of the plasma membrane whereas the ATP binding site of (Na+ +K+)-ATPase was located inside the membrane. Concanavalin A induced an early stimulation of Mg2+-APTase and (Na+ +K+)-ATPase both on intact cells and purified plasma membranes. In contrast, 5'-nucleotidase activity was not affected by the mitogen. Although the thymocyte Mg2+-ATPase activity was 3-5 times lower than in spleen lymphocytes, it was much more stimulated in the former cells (about 40 versus 20%). (Na+ +K+)-ATPase activity was undectectable in thymocytes. However, in spleen lymphocytes (Na+ +K+)-ATPase activity can be detected and was 30% increased by concanavalin A. Several aspects of this enzymic stimulation had also characteristic features of blast transformation induced by concanavalin A, suggesting a possible role of these enzymes, especially Mg2+-ATPase, in lymphocyte stimulation.
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PMID:Effect of concanavalin A on membrane-bound enzymes from mouse lymphocytes. 12 86

The influence of the mode of preparation upon some of the characteristics of white adipose tissue plasma membranes and microsomes has been reported. Plasma membrane fractions prepared from mitochondrial pellet were shown to have higher specific activities of (Mg2+ + Na+ + K+)-ATPase than plasma membranes originating in crude microsomes. Isolation of fat cells by collagenase treatment was found to result in a decrease in specific activity of the plasma membrane enzymes; in plasma membranes prepared from isolated fat cells, the specific activity values obtained for (Mg2+ + Na+ +k+)-ATPase and 5'-nucleotidase were only 42% and 6.3% respectively of those obtained in plasma membranes prepared from whole adipose tissue. Purification of whole adipose tissue crude microsomes by hypotonic treatment caused extensive solubilization of the endoplasmic reticulum marker enzymes, NADH oxidase and NADPH cytochrome c reductase. The lability of endoplasmic reticulum marker enzymes, however, was found to be greatly diminished in the preparations from isolated fat cells. The possibility that NADH oxidase and NADPH cytochrome c reductase activities found in the plasma membranes are microsomal enzymes adsorbed by the plasma membranes is discussed. The peptide patterns as well as the NADH oxidase and NADPH cytochrome c reductase activity patterns of plasma membranes and purified microsomes were compared by means of sodium dodecyl sulfate or Triton X-100 polyacrylamide gel electrophoresis.
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PMID:Comparison of plasma membranes and endoplasmic reticulum fractions obtained from whole white adipose tissue and isolated adipocytes. 12 89

An isolation procedure for synaptic plasma membranes from whole chick brain is reported that uses the combined flotation-sedimentation density gradient centrifugation procedure described by Jones and Matus (Jones, D. H. and Matus, A. I. (1974) Biochim. Biophys. Acta 356, 276-287) for rat brain. The particulate of the osmotically shocked and sonicated crude mitochondrial fraction was used for a flotation-sedimentation gradient step. Four fractions were recovered from the gradient after 30 min centrifugation. The fractions were identified and characterized by electron microscopy and by several markers for plasma membrane and other subcellular organelles. Fraction 2 was recovered from the 28.5-34% (w/v) sucrose interphase and contained the major part of the activities of the neuronal plasma membrane marker enzymes. The specific activities of the (Na+ +K+)-activated ATPase (EC 3.6.1.3), acetylcholinesterase (EC 3.1.1.7) and 5'-nucleotidase (EC 3.1.3.5) were, respectively, 4.5, 2.0 and 1.2 times higher than in the homogenate. However, Fraction 2 also contained considerable amounts of activities of putative lysosomal and microsomal markers in addition to lower amounts of mitochondrial and myelin markers. Although no prepurification of synaptosomes from the crude mitochondrial fraction was performed, the synaptic plasma membranes obtained showed many properties analogous to similar preparations from rat brain described in recent years.
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PMID:Isolation and partial characterization of chick brain synaptic plasma membranes. 13 94

Mouse leukemia L-1210 cells were iodinated with 125I; this permitted the development of a method for the isolation of the plasma membranes. These show a 10- to 16-fold increase in the specific activity of 125I over that of the cell homogenate and a 20-fold increase in the specific activities of 5'-nucleotidase and alkaline phosphatase; 20-fold increase in the specific activities of 5'-nucleotidase and alkaline phosphatase; no mitochondrial or microsomal marker enzyme activities were detected. Sodium dodecyl sulfate gel electrophoresis of the plasma membranes shows approx. 40 peptides with molecular weights ranging from 10 000 to over 200 000; a polypeptide (Mr 50 000) predominates. Of 13 iodinated surface membrane proteins, the major radioactive peptide has a molecular weight of 85 000. The importance of the selection of the appropriate gel system for the analysis of membrane proteins is emphasized.
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PMID:Isolation and characterization of the plasma membrane of L-1210 cells. Iodination as a marker for the plasma membrane. 16 26


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