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)

Several isozymes have been evaluated by other investigators to help characterize both mycoplasmas and acholeplasmas. We have investigated a number of enzymes contributing to hypoxanthine production in Ureaplasma urealyticum, as part of an ongoing effort to identify a comparative profile of isozyme activities in this species. Cells from large volume cultures were collected by centrifugation and lysed by both freeze-thawing and sonication in hypotonic buffer with Triton X-100. Lysate was clarified by centrifugation. Proteins in the cell lysate were separated by polyacrylamide gel electrophoresis, incorporating Triton X-100 in the gel and electrode buffer. Gels were stained to indicate sites of hypoxanthine production from AMP, adenosine, inosine, or adenine, in either phosphate or Tris buffer. The results suggest that adenine deaminase, inosine nucleosidase, and adenosine phosphorylase activities are present in the cell lysate, while adenosine nucleosidase and adenosine deaminase activities are absent. Inosine phosphorylase, AMP nucleosidase and/or 5'-nucleotidase activities may also be present. With the formation of hypoxanthine, the possibility for a salvage pathway exists.
 ...
PMID:Enzyme activities contributing to hypoxanthine production in Ureaplasma. 609

A simple chromatographic procedure with the use of modified cellulose-nitrate membrane strips, 80 x 40 mm, has been worked out for the rapid isotopic assay of cyclic AMP (cAMP) phosphodiesterase (EC 3.1.4.17) and 5'-AMP nucleotidase (EC 3.1.3.5) in crude extracts of various tissues from animals and plants. The assay is based on enzymatic conversion of the product to adenine, a relatively inert compound which, in contrast to cAMP and 5'-AMP, is strongly adsorbed by the cellulose-nitrate membrane. Due to this property rapid separation of adenine from the unconverted substrate (cAMP or 5'-AMP) is possible. Commercial 5'-nucleotidase and easily obtainable crude extract of adenosine nucleosidase from barley leaves are used as coupling enzymes for the phosphodiesterase assay. The assay of phosphodiesterase in 0.5-2 microliter of blood (10(-5) to 4.10(-5) units) has been demonstrated on several examples.
 ...
PMID:Rapid assay of cyclic AMP phosphodiesterase and 5'-nucleotidase by means of chromatography on cellulose-nitrate membrane strips. 628 14

Recent advances in cytokinin analysis have made it possible to measure the content of 22 cytokinin metabolites in the tissue of developing tobacco seedlings. Individual types of cytokinins in plants are interconverted to their respective forms by several enzymatic activities (5'-AMP-isopentenyltransferase, adenosine nucleosidase, 5'-nucleotidase, adenosine phosphorylase, adenosine kinase, trans-hydroxylase, zeatin reductase, beta-glucosidase, O-glucosyl transferase, N-glucosyl transferase, cytokinin oxidase). This paper reports modelling and measuring of the dynamics of endogenous cytokinins in tobacco plants grown on media supplemented with isopentenyl adenine (IP), zeatin (Z) and dihydrozeatin riboside (DHZR). Differences in phenotypes generated by the three cytokinins are shown and discussed, and the assumption that substrate concentration drives enzyme kinetics underpinned the construction of a simple mathematical model of cytokinin metabolism in developing seedlings. The model was tested on data obtained from liquid chromatography/tandem mass spectrometry cytokinin measurements on tobacco seedlings grown on Murashige and Skoog agar nutrient medium, and on plants grown in the presence of IP, Z and DHZR. A close match was found between measured and simulated data, especially after a series of iterative parameter searches, in which the parameters were set to obtain the best fit with one of the data sets.
 ...
PMID:Dynamics of endogenous cytokinin pools in tobacco seedlings: a modelling approach. 1264 3

Extracellular ATP (eATP) has recently been demonstrated to play a crucial role in plant development and growth. To investigate the fate of eATP within the apoplast, we used intact potato (Solanum tuberosum) tuber slices as an experimental system enabling access to the apoplast without interference of cytosolic contamination. (i) Incubation of intact tuber slices with ATP led to the formation of ADP, AMP, adenosine, adenine and ribose, indicating operation of apyrase, 5'-nucleotidase and nucleosidase. (ii) Measurement of apyrase, 5'-nucleotidase and nucleosidase activities in fractionated tuber tissue confirmed the apoplastic localization for apyrase and phosphatase in potato and led to the identification of a novel cell wall-bound adenosine nucleosidase activity. (iii) When intact tuber slices were incubated with saturating concentrations of adenosine, the conversion of adenosine into adenine was much higher than adenosine import into the cell, suggesting a potential bypass of adenosine import. Consistent with this, import of radiolabeled adenine into tuber slices was inhibited when ATP, ADP or AMP were added to the slices. (iv) In wild-type plants, apyrase and adenosine nucleosidase activities were found to be co-regulated, indicating functional linkage of these enzymes in a shared pathway. (v) Moreover, adenosine nucleosidase activity was reduced in transgenic lines with strongly reduced apoplastic apyrase activity. When taken together, these results suggest that a complete ATP salvage pathway is present in the apoplast of plant cells.
 ...
PMID:A cell wall-bound adenosine nucleosidase is involved in the salvage of extracellular ATP in Solanum tuberosum. 1877 87