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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)

The activities of guanylate cyclase, guanosine 3', 5'-monophosphate (cyclic GMP) phosphodiesterase and 5'-nucleotidase were measured during postnatal development in retinas of control and C3H/HeJ mice. In control retina, each of these enzyme activities increases in conjunction with photoreceptor cell differentiation and maturation. In C3H retina, guanylate cyclase and 5-nucleotidase activities increase with photoreceptor cell development and decrease with photoreceptor cell death. However, the activity of a class of cyclic GMP phosphodiesterase which distinguishes the photoreceptor cells of control mice and those of several other species is not demonstrable in retina of C3H mice at any age. It is suggested that the deficiency in cyclic GMP phosphodiesterase activity may account for the accumulation of cyclic GMP which has been shown to occur in the C3H photoreceptor cells before they degenerate.
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PMID:Enzymic basis for cyclic GMP accumulation in degenerative photoreceptor cells of mouse retina. 0 93

An increase of thymidine kinase [EC 2.7.1.21] activity and decrease of 5'-nucleotidase [EC 3.1.3.5] activity for dTMP were found during hormonal regeneration of the seminal vesicles by daily or single administration of testosterone propionate into mice castrated 2 weeks previously. Actinomycin D injected on day 0 of testosterone treatment completely inhibited both the increase of thymidine kinase and the decrease of 5'-nucleotidase. When injected on day 2, actinomycin D decreased thymidine kinase activity below the control level and 5'nucleotidase activity was not restored to the normal level. The activity of 5'-nucelotidase in a mixed sample, in which seminal vesicles of castrated mice and those of testosterone-treated mice were homogenized together, was intermediate between the activities determined separately. This indicates the absence of any inhibitor of 5'nucleotidase in the regenerating vesicles. Changes in total activity of 5'nucleotidase and total protein content in extracts during various treatments showed that the decrease in specific activity of 5'-nucleotidase in the first 2 days of testosterone treatment was not due to inhibition of enzyme activity but to dilution of the enzyme with other proteins which increased in content more rapidly than 5'-nucleotidase.
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PMID:Changes in enzyme activities of thymidine kinase and 5'-nucleotidase for dTMP during hormonal regeneration of seminal vesicles of mice. 7 66

Electron microscopic cytochemical localization of Mg++-activated adenosine triphosphatase (Mg++-ATPase) and 5-nucleotidase (AMPase) was investigated in bile canaliculus-rich and bile duct-containing fractions isolated from rat liver. Comparative cyochemical studies between prefixed and non-prefixed fractions revealed that the activity of both enzymes could be detected in the fractions under appropriate experimental conditions. However, the cytochemical activity of AMPase was much more sensitive to glutaraldehyde than that of Mg++-ATPase. Mg++-ATPase and AMPase reaction products were localized primarily on bile canalicular microvilli, that is, along the outer (luminal) surface of canalicular plasma membranes, but they were never observed on bile ductal microvilli. AMPase was also detectable on lateral hepatic plasma membranes. Mg++-ATPase demonstrated by the cytochemical technique described is a reliable enzyme marker for isolated bile canalicular membranes. At high magnification, Mg++-ATPase reaction product was also observed on the microfilaments surrounding isolated bile canaliculi. The possibility that the reaction product on the pericanalicular microfilaments may result from the hydrolysis of ATP byan actomyosin ATPase-like enzyme associated with these filaments is briefly discussed.
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PMID:Electron microscopic cytochemical characterization of bile canaliculi and bile ducts in vitro. 12 97

In the present paper the mechanism of the adenosine formation by a mixture of nerve ending and transmitter granula fractions was invesitgated. The adenosine formation in vivo is only possible via the whole degradation chain ATP - ADP - AMP - adenosine. The enzymes involved are ATPases, adenylate kinase and 5'-nucleotidase. The ATPase and adenylate kinase effectors Ca++ and Mg++ can be regarded as trigger ions switching on and off the degradation chain. The adenylate kinase represents a key enzyme within the whole chain. In the ion-activated state a non-inhibited adenosine formation was observed, when the initial ATP concentration amounted to less than 0,1 muMol per mg synaptosomal membrane protein. Under these conditions the whole chain velocity is mainly dependent on the 5'-nucleotidase concentration, because ATPases and adenylate kinase remove the nucleotidase inhibitors ATP and ADP spontanously. The conditions for the optimal velocity of the adenosine formation at the synaptic membrane in vivo in all probability are present. A hypothesis for the mechanism of the synaptic adenosine formation in vivo was developed. The importance of this process in respect to the synaptic transmission was discussed.
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PMID:[Mechanism of synaptosomal degradation of ATP in connection with involvement of adenosine in the transmission process]. 12 26

Thymine-containing compounds, produced degradation of Escherichia coli DNA after infection of the cells with bacteriophage T5, did not accumulate in the cell but were excreted into the medium as the DNA was degraded. The ultimate degradation product was extracellular thymine that was not reutilized when T5 DNA synthesis began. This excretion of thymine may have been due in part to the induction of 5'-nucleotidase activity within 3 min after T5 infection. The level of this activity reached a maximum between 4 to 6 min after infection and then rapidly declined to its preinfection level by 10 to 15 min after infection. Chloramphenicol added before or soon after infection prevented the appearance of the nucleotidase. The induced nucleotidase activity was active not only on dTMP but also on dAMP, dGMP, and dCMP.
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PMID:Early events after infection of Escherichia coli by bacteriophage T5. Induction of a 5'-nucleotidase activity and excretion of free bases. 16 55

A simple method, involving NAD+-Sepharose chromatography, was developed for the preparation of snake venom phosphodiesterase (EC 3.1.4.1) almost free from 5'-Nucleotidase (EC 3.1.3.5). Using an NAD+-Sepharose 4B column, phosphodiesterase was eluted in the unadsorbed fraction, whereas 5'nucleotidase was strongly adsorbed. The latter enzyme was desorbed when 0.2 M sodium bicarbonate buffer containing 1mM beta-NADH was used as a solvent. The affinity column could be used at least four times without any decrease of potency, and the method was applicable for the preparation of phosphodiesterase from the venoms of rattlesnake (Crotalus adamanteus) and Japanese mamushi (Agkistrodan halys blomhoffi).
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PMID:A simple method for preparation of snake venom phosphodiesterase almost free from 5'-nucleotidase. 16 89

The control of activity of the bacteriophage T5-induced 5'-nucleotidase is dependent upon the amount of T5 parental DNA injected into the cell and expressed. When only the first-step transfer DNA is injected and expressed the amount of 5'-nucleotidase activity observed is two to three times the maximum amount observed after normal T5 infection, and inactivation of the enzyme does not occur. Enzyme inactivation occurs only after the remaining DNA is injected, but only limited expression of this DNA is required. The control of the nucleotidase inactivation process is similar to that for the repair of the nicks in parental DNA, and is probably mediated by a class IIa protein.
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PMID:Early events after infection of Escherichia coli by bacteriophage T5. II. Control of the bacteriophage-induced 5'-nucleotidase activity. 17 72

A procedure is described for isolating two membrane fractions from rabbit spinal-cord white matter enriched with 5'-nucleotidase, a nonspecific plasma membrane marker, 2',3'-cyclic nucleotide phosphohydrolase, an oligodendroglial plasma membrane marker, and acetylcholinesterase, an axonal plasma membrane marker. While the two membrane fractions exhibited similar enrichments with respect to cyclic nucleotide phosphohydrolase, enrichments of 5'-nucleotidase and acetylcholinesterase were significantly greater in the heavier membrane fraction. Selected enzyme markers for cyto- and mitochondrial membranes were not detected. Moreover, gray matter did not yield homologous membrane fractions in the gradient when subjected to the identical procedure, indicating that the two membrane fractions were unique to white matter. While electronmicroscopic examination revealed that both membrane fractions were comtaminated with myelin, the heavier fraction was least contaminated and exhibited a fair degree of homogeneity with respect to single membrane vesicular profiles. It was concluded that both membrane fractions were enriched with oligodendroglial and axonal plasma membranes, with the heavier fraction containing significantly more axolemma.
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PMID:Isolation of non-myelin plasma membranes unique to white matter. 19 99

Activity of enzymes catalizing bioenergetic processes of substance transport through cell membranes, adenosine triphosphatase and para-nitrophenyl phosphates, activity of certain enzymes of carbohydrate metabolism, lactate dehydrogenase and glucose-6-phosphate dehydrogenase, as well as to 5'-nucleotidase taking part in nucleic metabolism were determined in the pancreas of thyreoidectomized rats. Simultaneously the content of lactic acid, phosphorus, potassium and sodium, which immediately related to activation of the mentioned enzymes, was determined in the pancreas. In thyroidectomized rats the activity of Mg2+, Na+, K+-ATPase, Na+, K+-ATPase and lactate dehydrogenase in the pancreas increases, that of glucose-6-phosphate dehydrogenase, para-nitrophenylphosphatase and 5-nucleotidase decreases, the content of lactic acid, potassium, sodium and phosphorus increases.
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PMID:[Adenosine triphosphatase, lactate dehydrogenase and glucose-6-phosphate dehydrogenase activity of pancreas of thyroidectomized rats]. 20 6

1. The maximal activities of 5'-nucleotidase, adenosine kinase and adenosine deaminase together with the Km values for their respective substrates were measured in muscle, nervous tissue and liver from a large range of animals to provide information on the mechanism of control of adenosine concentration in the tissues. 2. Detailed evidence that the methods used were optimal for the extraction and assay of these enzymes has been deposited as Supplementary Publication SUP 50088 (16pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K.,from whom copies can be obtained on the terms indicated in Biochem. J. (1978), 169, 5. This evidence includes the effects of pH and temperature on the activities of the enzymes. 3. In many tissues, the activities of 5'-nucleotidase were considerably higher than the sum of the activities of adenosine kinase and deaminase, which suggests that the activity of the nucleotidase must be markedly inhibited in vivo so that adenosine does not accumulate. In the tissues in which comparison is possible, the Km of the nucleotidase is higher than the AMP content of the tissue, and since some of the latter may be bound within the cell, the low concentration of substrate may, in part, be responsible for a low activity in vivo. 4. In most tissues and animals investigated, the values of the Km of adenosine kinase for adenosine are between one and two orders of magnitude lower than those for the deaminase. It is suggested that 5'-nucleotidase and adenosine kinase are simultaneously active so that a substrate cycle between AMP and adenosine is produced: the difference in Km values between kinase and deaminase indicates that, via the cycle, small changes in activity of kinase or nucleotidase produce large changes in adenosine concentration. 5. The activities of adenosine kinase or deaminase from vertebrate muscles are inversely correlated with the activities of phosphorylase in these muscles. Since the magnitude of the latter activities are indicative of the anaerobic nature of muscles, this negative correlation supports the hypothesis that an important role of adenosine is the regulation of blood flow in the aerobic muscles.
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PMID:Activities and some properties of 5'-nucleotidase, adenosine kinase and adenosine deaminase in tissues from vertebrates and invertebrates in relation to the control of the concentration and the physiological role of adenosine. 21 26


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