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)

An exocellular pyrophosphatase, active on the nucleotide precursors of peptidoglycans, has been found in the culture medium of Streptomyces mediterranei ME/R 17. This enzyme was separated from the DD-carboxypeptidase by batchwise adsorption on DEAE cellulose. The pyrophosphatase had no strict substrate requirements, it hydrolyzed various UDP-sugar substrates: UDP-GlcNAc, UDP-Mur NAc and UDP-MurNAc peptides, giving rise to the corresponding sugar phosphate and to UMP. The enzyme preparation also contained a 5'-nucleotidase activity and UMP was further split to give uridine. This nucleotidase activity was inhibited by potassium tetraborate. Both cytoplasmic and particulate preparations from cells of S. mediterranei also contained a pyrophosphatase activity while only the particulate fractions showed the DD-carboxypeptidase activity. The pyrophosphatase excretion was tested during the grwoth cycle. The activity of the enzyme showed a constant increase throughout the exponential growth and a stronger increase in the late exponential phase. Such a result could be correlated with a consumption of the nutrients in the culture medium, in fact a relatively poor culture medium had a strong positive effect upon the production of the exocellular pyrophosphatase.
 ...
PMID:[Identification of an extracellular nucleotide pyrophosphatase in the culture media of Streptomyces mediterranei ME/R 17]. 42 55

1. A mouse liver plasma-membrane preparation was solubilized in an N-dodecylsarcosinate-Tris buffer, pH7.8, and the proteins and glycoproteins were separated by a rate-zonal centrifugation in sucrose-detergent gradients. 2. A peak of alkaline phosphodiesterase activity which sedimented ahead of the 5'-nucleotidase peak was associated with a major glycoprotein component of the plasma membrane. 3. The phosphodiesterase activity was then purified further by gel filtration and gave a single glycoprotein band after electrophoresis on polyacrylamide gels. The apparent molecular weight of the polypeptide at pH7.4 and 8.9 was 128000-130000 and was independent of the polyacrylamide concentration. Electrophoresis in gels containing deoxycholate showed that the protein band was coincident with phosphodiesterase activity. 4. After two-dimensional immunoelectrophoresis, with agarose containing rabbit anti-(mouse plasma-membrane) antiserum as second dimension, the enzyme showed one component which was also coincident with the phosphodiesterase activity. 5. An amino acid composition of the glycoprotein is presented. Carbohydrate analysis indicated the presence of glucosamine, neutral sugars and sialic acid. 6. The enzyme was also a nucleotide pyrophosphatase, as shown by a similar enrichment during purification of activity towards ATP, NAD(+), UDP-galactose and UDP-N-acetylglucosamine. The phosphodiesterase activity, measured by using dTMP p-nitrophenyl ester as substrate, was competitively inhibited by nucleotide pyrophosphate substrates. The enzyme showed little or no activity towards RNA, cyclic AMP, AMP, ADP and glycerylphosphorylcholine. 7. The significance of this enzyme activity in the plasma membrane is discussed.
 ...
PMID:Purification and properties of a mouse liver plasma-membrane glycoprotein hydrolysing nucleotide pyrophosphate and phosphodiester bonds. 436 Feb 50

Hyaluronate could be labelled in vivo with [32P]phosphate. [32P]UDP in an alpha-glycosidic linkage constituted the reducing end of membrane-bound hyaluronate. The UDP is liberated during further chain elongation, indicating that chain growth occurs at the reducing end. [3H]Uridine could be incorporated into hyaluronate during synthesis on the isolated membraneous fraction from [3H]UDP-GlcNAc and [3H]UDP-GlcA, confirming the identification of UDP as a constituent of membrane-bound hyaluronate. These results led to a model of hyaluronate chain elongation at the reducing end by alternate addition of the chains to the substrates. Membrane-bound pyrophosphatases or 5'-nucleotidase are suggested as modulators of hyaluronate synthesis.
 ...
PMID:Synthesis of hyaluronate in differentiated teratocarcinoma cells. Mechanism of chain growth. 687 Aug 20

Plasma membranes have been isolated from chicken liver and from Mc-29 virus induced transplantable hepatoma. The purity of membrane preparations has been checked by electron microscopy and by determination of the activity of some enzymes: 5'-nucleotidase, Na+, K+-ATP-ase, Mg2+-ATP-ase, alkaline beta-glycerophosphatase and glucose-6-phosphatase. In hepatoma membranes the activity of 5'-nucleotidase, Na+, K+-ATP-ase and Mg2+-ATP-ase was lower, that of alkaline phosphatase higher, than in liver membrane preparation. The incorporation rate of glucosamine-14C into UDP-N-acetylglucosamine and into plasma membrane glucosamine have been studied as well. The rate of synthesis of UDP-N-acetylglucosamine was faster in liver than in tumor cells. The labeling of hepatoma plasma membranes with glucosamine-14C occurred more slowly than that of liver ones. The rate of transfer of N-acetylglucosamine from UDP-N-acetylglucosamine to membrane-bound glucosamine is lower in hepatoma, than in liver cells.
 ...
PMID:Isolation and partial characterization of plasma membranes from chicken liver and from Mc-29 virus induced transplantable hepatoma. 745 56

Adult rat testis homogenates were fractionated by differential centrifugation followed by two discontinuous gradient centrifugation steps under identical conditions except for the absence of digitonin in the first gradient and the presence of 0.03% digitonin in the second gradient. The first gradient centrifugation yielded a membrane fraction enriched 28.8-fold in 5'-nucleotidase, 21.5-fold in UDP-Gal:GlcNAc galactosyltransferase and 18.6-fold in UDP-GlcNAc:alpha-D-mannoside N-acetylglucosaminyltransferase. Repeat centrifugation of this membrane fraction in the denser level of the gradient; this material was enriched 32.1-fold in 5'-nucleotidase but only 1.9-fold in galactosyltransferase and 8.4-fold in N-acetylglucosaminyltransferase. The plasma membrane fraction was shown to be free of glucose-6-phosphatase, succinate dehydrogenase, beta-N-acetylglucosaminidase, DNA, and RNA. The fraction therefore appears to be enriched in plasma membrane but relatively free of Golgi membrane contamination, as indicated by the relatively low levels of glycosyltransferases, and of contamination by other organelles. The testicular cells which contribute plasma membrane to this fraction have not yet been definitively identified; the contribution by Sertoli cells is particularly difficult to assess since these cells have been reported to be enriched in 5'-nucleotidase. However, sulfogalactosylalkylacylglycerol (SGG), a lipid previously shown to be present primarily in primary spermatocytes, spermatids, and spermatozoa, was enriched 33.1-fold in the plasma membrane fraction; this finding as well as experiments with [35S]sulfate-labeled sulfogalactosylalkylacylglycerol at various times after injection of radioactive label have indicated that both spermatocytes and spermatids were contributing SGG-rich membrane material to our plasma membrane preparation. This membrane material is most probably derived from the plasma membranes of the spermatocytes and spermatids.
 ...
PMID:Enrichment of sulfogalactosylalkylacylglycerol in a plasma membrane fraction from adult rat testis. 745 82