Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.1.1 (asparaginase)
 2,695 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lymphoma 6C3HED-OG cells, known from previous work to be susceptible to the effects of guinea pig serum in vivo and dependent upon extrinsic asparagine for protein synthesis and growth in vitro, remained for the most part morphologically intact and countable in the electronic cell counter following exposures of 1 and 2 hr to the effects of heated (56 degrees C, 30 min) guinea pig serum injected into the peritoneal cavities of mice in which the lymphoma cells were growing rapidly; after exposures of 4 and 6 hr the bulk of the -OG cells remained still intact and countable in the cell counter, though by this time a small proportion of them (5 to 12%) proved stainable with eosin in wet preparations) hence were presumably nonviable. After 12, 16, and 24 hr of exposure, however, the bulk of the -OG cells were either lysed or fragmented, to the extent that they did not register in the cell counter. Morphologic studies of the cells exposed 16 and 24 hr to the effects of heated guinea pig serum in vivo, disclosed that most of the cells then remaining were either frankly necrotic or greatly altered otherwise, marked vacuolation of the cytoplasm being the most conspicuous alteration in cells not yet obviously necrotic. Long before the bulk of the Lymphoma 6C3HED-OG cells had become conspicuously changed morphologically following exposure to the effects of heated guinea pig serum in vivo, they manifested striking alterations in protein metabolism, as was disclosed by "pulse" studies with radioactive valine. For example, the protein metabolism of -OG cells, as measured by their incorporation of L-valine-C(14), was sharply curtailed following 15 min of exposure to heated guinea pig serum in vivo, as compared with valine incorporation by cells labeled immediately after exposure to the guinea pig serum. Following exposure to heated guinea pig serum during 60 min, -OG cells incorporated less than half as much L-valine-C(14) as did cells labeled immediately after exposure, and the incorporation of L-valine-C(14) was still less after 120 min of exposure. By contrast, Lymphoma -RG1 cells, known from previous work to be wholly insusceptible to the effects of guinea pig serum in vivo and independent of need for extrinsic asparagine for protein synthesis and growth in vitro, showed no curtailment whatever of protein synthesis following exposures to the effects of heated guinea pig serum in vivo during periods of 15, 60, and 120 min. Reasons are given for considering the prompt inhibition of protein synthesis in the asparagine-dependent -OG cells a direct result of asparagine-deprivation induced in vivo by the injected guinea pig serum, the L-asparaginase of which presumably converted the available L-asparagine of the host to L-aspartic acid that was not taken up by the -OG cells. The synthesis of deoxyribonucleic acid by Lymphoma 6C3HED-OG cells, as measured by the incorporation of thymidme-H(3), determined with the aid of liquid scintillation counting and autoradiography, was also altered by exposure of the lymphoma cells to the effects of heated guinea pig serum in vivo, though not during exposures of 15 and 60 min; only after an exposure of 120 min did the population of -OG cells incorporate notably less thymidine-H(3) than did control populations, though after 240 min of exposure the -OG cells incorporated less than one-fifth as much tritiated thymidineas had -OG cells exposed to heated guinea pig serum for 60 min or to heated horse serum for periods up to 240 min. Autoradiographs indicated that DNA synthesis by -OG cells normally proceeds at an intense level that leads to some 60% of these cells being heavily labeled in autoradiographs at any given time; after exposure to the effects of heated guinea pig serum during 2 and 4 hr in vivo, however, the lymphoma cells lost their ability to incorporate enough tritiated thymidine to become heavily labeled, but approximately the same proportion of them (56 to 58%) retained their ability to incorporate sufficient tritiated thymidine to become lightly labeled. The possibility is considered that the inhibition of DNA synthesis in the asparagine-dependent -OG cells exposed to the effects of heated guinea pig serum in vivo may be secondary to the previously manifest inhibition of protein synthesis. Further, in tests of ribonucleic acid metabolism of Lymphoma 6C3HED-OG cells after exposure to the effects of heated guinea pig serum in vivo during periods of 15, 60, 120, and 240 min, the findings indicated that the ability of the lymphoma cells to synthesize RNA, as measured by their capacity to incorporate uridine-5-H(3), remained unaltered during the exposures of 15, 60, and 120 min, but was substantially reduced following 240 min of exposure. The findings are considered in relation to the probability, disclosed in part by previous studies, that heated guinea pig serum brings about its effects upon Lymphoma 6C3HED-OG cells in vivo by providing active L-asparaginase in large amounts, which presumably converts the available (extracellular) asparagine of the host to aspartic acid, the latter not being taken up by the lymphoma cells in vivo or in vitro. Hence it seems likely that heated guinea pig serum in this way brings about a state of asparagine deprivation that is responsible for the sequential metabolic and morphologic alterations that become manifest in asparagine-dependent Lymphoma 6C3HED-OG cells following their exposure to the effects of guinea pig serum in vivo, as here described.
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PMID:Alterations in protein and nucleic acid metabolism of lymphoma 6C3HED-og cells in mice given guinea pig serum. 590 71

Escherichia coli asparaginase II catalyzes the hydrolysis of L-asparagine to L-aspartate via a threonine-bound acyl-enzyme intermediate. A nearly inactive mutant in which one of the active site threonines, Thr-89, was replaced by valine was constructed, expressed, and crystallized. Its structure, solved at 2.2 A resolution, shows high overall similarity to the wild-type enzyme, but an aspartyl moiety is covalently bound to Thr-12, resembling a reaction intermediate. Kinetic analysis confirms the deacylation deficiency, which is also explained on a structural basis. The previously identified oxyanion hole is described in more detail.
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PMID:A covalently bound catalytic intermediate in Escherichia coli asparaginase: crystal structure of a Thr-89-Val mutant. 870 62

Net balances of amino acids were constructed for stages of development of a leaf of white lupin (Lupinus albus L.) using data on the N economy of the leaf, its exchanges of amino acids through xylem and phloem, and net changes in its soluble and protein-bound amino acids. Asparagine, aspartate, and gamma-aminobutyrate were delivered to the leaf in excess of amounts consumed in growth and/or phloem export. Glutamine was supplied in excess until full leaf expansion (20 days) but was later synthesized in large amounts in association with mobilization of N from the leaf. Net requirements for glutamate, threonine, serine, proline, glycine, alanine, valine, isoleucine, leucine, tyrosine, phenylalanine, histidine, lysine, and arginine were met mainly or entirely by synthesis within the leaf. Amides furnished the bulk of the N for amino acid synthesis, asparagine providing from 24 to 68%. In vitro activity of asparaginase (EC 3.5.1.1) exceeded that of asparagine:pyruvate aminotransferase (EC 2.6.1.14) during early leaf expansion, when in vivo estimates of asparagine metabolism were highest. Thereafter, aminotransferase activity greatly exceeded that of asparaginase. Rates of activity of one or both asparagine-utilizing enzymes exceeded estimated rates of asparagine catabolism throughout leaf development. In vitro activities of glutamine synthetase (EC 6.3.1.2) and glutamate synthase (EC 1.4.7.1) were consistently much higher than that of glutamate dehydrogenase (EC 1.4.1.3), and activities of the former two enzymes more than accounted for estimated rates of ammonia release in photorespiration and deamidation of asparagine.
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PMID:Amino Acid transport and metabolism in relation to the nitrogen economy of a legume leaf. 1666 17

Green 'Anjou' pear and its bud mutation, red 'Anjou' were compared to understand their differences in phenolic metabolism and its effect on primary metabolism. In the flesh of the two cultivars, no difference was detected in the concentration of any phenolic compound, the transcript level of MYB10 or the transcript levels or activities of key enzymes involved in anthocyanin synthesis. Compared with green 'Anjou', the shaded peel of red 'Anjou' had higher anthocyanin concentrations, higher transcript levels of MYB10 and higher activity of UDP-glucose:flavonoid 3-O-glycosyltransferase (UFGT), suggesting that MYB10 regulates UFGT to control anthocyanin synthesis in red 'Anjou' peel. In the sun-exposed peel, activities of phenylalanine ammonia lyase, dihydroflavonol reductase, flavonol synthase and anthocyanidin synthase as well as UFGT were higher in red 'Anjou' than in green 'Anjou'. The peel of red 'Anjou' had higher activities of sorbitol dehydrogenase, raffinose synthase and sucrose synthase and higher levels of raffinose, myo-inositol and starch, indicating that sorbitol metabolism, raffinose synthesis and starch synthesis were upregulated in red 'Anjou'. The flesh of red 'Anjou' had higher concentrations of glucose, but lower activities of ATP-dependent phosphofructokinase, pyruvate kinase and glucose-6-phosphate dehydrogenase and lower dark respiration. The peel of red 'Anjou' had higher activities of glutaminase, asparagine synthetase and asparaginase, and higher concentrations of asparagine, aspartate, alanine, valine, threonine and isoleucine. The effects of anthocyanin synthesis on primary metabolism in fruit peel are discussed.
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PMID:Comparison of phenolic metabolism and primary metabolism between green 'Anjou' pear and its bud mutation, red 'Anjou'. 2410 57