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

An intracellular L-asparaginase with antitumour activity was purified from a strain of Citrobacter. The optimum conditions for enzyme production by fermentation on scales up to 2700 l were investigated. Highest enzyme yield was obtained in corn-steep liquor medium (9-2%, W/V) at 37 degrees C. Oxygen limitation was not necessary for high enzyme yield. A total recovery of 4-3% from nucleic-acid-free extract and a 180-fold increase in specific activity were obtained after purificaiton. The specific activity of the purified preparation was 45 i.u./mg protein. The enzyme hydrolysed D-asparagine and L-glutamine at 7 and 5%, respectively, of its activity toward L-asparagine, but L-glutaminase activity could be demonstrated only at substrate concentrations above 5 mM. The Km values for L-asparagine and D-asparagine were 2-6 X 10(-5) and 1-4 X 10(-4) respectively. The anti-lymphoma activity of the enzyme was demonstrated with Gardner lymphosarcoma and was found only slightly less potent that Crasnitin, the most active asparaginase so far tested in this system.
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PMID:The properties and large-scale production of L-asparaginase from citrobacter. 0 Apr 65

The effect of low pH values on the activity and stability of the quaternary structure of asparaginase from Escherichia coli was investigated at early stages of purification of the enzyme. Acidification of the E. coli extract was most effective before the biomass separation. This procedure helped to separate biomass together with coagulated ballast proteins and not to reduce the activity. Upon storage of the acidified solution at 5 degrees C reversible dissociation of the tetrametric structure into dimers and monomers occurred. Stability of L-asparaginase in the storage of acetone powders and during extraction was studied. It is suggested that asparaginase in bacterial cells in unlikely to have the quaternary structure which normally occurs in the solution at neutral pH.
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PMID:[Effect of different pH values on the activity and quaternary structure of asparaginase in Escherichia coli extracts]. 0 37

Highly purified L-asparaginase having a specific activity of 500+/- +/-40 IU./mg protein is isolated from Pseudomonas fluorescens AG cells. The purification procedure includes isopropanol fractionation, gel filtration through Sephadex G-100, chromatography on hydroxylapatite and DEAE-cellulose columns. The asparaginase preparation is homogenous on the basis of polyacrylamide gel electrophoresis data. The pH optimum is found to be 8.0-9.0, isoelectric point and molecular weight are 4.5+/-0.05 and 70,000+/-5,000 respectively, Km for L-asparagine being-4.1-10(-4)M. The enzyme does not hydrolyse L-glutamine. The hydrolysis rate of D-glutamine is less than 1% of the deamydation rate of L-isomer. p-Chloro-mercurium benzoate at a concentration of 10(-4) M completely inhibits the asparaginase activity. Asparaginase from Ps. fluorescens AG possesses and antileucosic activity, inhibiting 3H-thymidine incorporation into DNA of Berkit lymphoma cells.
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PMID:[Isolation and properties of a homogeneous L-asparaginase preparation from Pseudomonas fluorescens AG]. 0 29

An extracorporeal reactor containing a packed bed of Dacron fibers has been developed. Escherichia coli II L-asparaginase was coupled to the Dacron using gamma-aminopropyltriethoxysilane and glutaraldehyde. The preparation had an activity of 37 IU per gram of Dacron (37 degrees C). The apparent Km was studied as a function of the flow rate. The data indicated that the apparent Km approached the Km of the native enzyme at flow rates of about 300 mg/min. In vivo use of L-asparaginase immobilized on the Dacron indicated effective lowering of plasmatic L-asparagine levels.
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PMID:A Dacron wool packed-bed extracorporeal reactor: a kinetic study of immobilized Escherichia coli II L-asparaginase. 0 8

An L-asparaginase has been purified some 250-fold from extracts of Klebsiella aerogenes to near homogeneity. The enzyme has a molecular weight of 141,000 as measured by gel filtration and appears to consist of four subunits of molecular weight 37,000. The enzyme has high affinity for L-asparagine, with a Km below 10(-5) M, and hydrolyzes glutamine at a 20-fold lower rate, with a Km of 10(-3) M. Interestingly, the enzyme exhibits marked gamma-glutamyltransferase activity but comparatively little beta-aspartyl-transferase activity. A mutant strain lacking this asparaginase has been isolated and grows at 1/2 to 1/3 the rate of the parent strain when asparagine is provided in the medium as the sole source of nitrogen. This strain grows as well as the wild type when the medium is supplemented with histidine or ammonia. Glutamine synthetase activates the formation of L-asparaginase. Mutants lacking glutamine synthetase fail to produce the asparaginase, and mutants with a high constitutive level of glutamine synthetase also contain the asparaginase at a high level. Thus, the formation of asparaginase is regulated in parallel with that of other enzymes capable of supplying the cell with ammonia or glutamate, such as histidase and proline oxidase. Formation of the asparaginase does not require induction by asparaginase and is not subject to catabolite repression.
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PMID:L-Asparaginase of Klebsiella aerogenes. Activation of its synthesis by glutamine synthetase. 0 59

1. L-asparaginase from M. phlei was purified about 170-fold with an 11% yield. The purification procedure consisted of: fractionation with ammonium sulphate; adsorption of contaminating proteins on calcium phosphate gel; chromatography on Sephadex G-150 and DEAE-cellulose. The specific activity of the final preparation was 32.6 i.u./mg protein. 2. Molecular weight of the enzyme as determined by Sephadex G-100 filtration amounted to 126 000. Optimum pH was 8.8-9.2. The enzyme did not hydrolyse L-glutamine over the pH range 4-9, and was inhibited by D-asparagine. The apparent Michaelis constant for L-asparagine was 0.7 mM; energy of activation, 9800 cal/mole. 3. On polyacrylamide-gel electrophoresis the final preparation revealed two protein bands, one of which was coincident with the enzyme activity.
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PMID:Purification and properties of L-asparaginase from Mycobacterium phlei. 0 91

The tryptophanyl fluorescence of Escherichia coli B L-asparaginase is partially quenched by the protonated form of a base with pKa 6.0 at 25 degrees C, mu = 0.1. This base has been identified as a histidyl residue through the effect of ionic strength and solvent polarity on the pKa. In addition diethylpyrocarbonate which modifies two histidyl residues in the enzyme abolishes the fluorescenc titration and reduces enzymic activity by 90%. The temperature dependence of the histidine pKa is unusual, showing a minimum at 25 degrees C, a thermodynamic analysis of the data shows this to be due to a large negative delta Cp term associated with the ionisation. This is interpreted in terms of the movement of hydrophobic residues into the enzyme on deprotonation of the histidyl residue. The quantum yield of L-asparaginase and its temperature dependence have been measured. The quantum yield is high and there is a low activation energy for radiationless deactivation of the excited state both of which are consistent with a tryptophanyl environment remote from the solvent.
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PMID:An investigation of an unusual histidyl residue in Escherichia coli B L-asparaginase through fluorescence quenching. 0 4

L-Asparagine synthetase appears in serum approximately 7 days after the s.c. implantation of 1 X 10(5) cells of Leukemia 5178Y/AR (resistant to L-asparaginase) and increases in activity as the neoplasm grows and metastasizes. The principal source of the enzyme is the primary tumor. After intravranial inoculation of tumor, the rate of leakage of the enzyme is more pronounced than when the subcutaneous, intramuscular, or intraperitoneal routes are used. 1-(2-Chloroethyl)-3-cyclohexyl-1-nitrosourea (NSC 79037), a nitro-sourea effective in the palliation of L5178Y/AR, temporarily halts the influx of enzyme into the blood stream, as does surgical excision of the s.c. tumor nodules. Treatment of mice with L-asparaginase within 24 hr of inoculation of the tumor markedly augments both tumor growth and the rate of penetration of L-asparagine synthetase into the circulation. Several other L-asparagine synthetase into the circulation. Several other L-asparaginase-resistant tumors also were found to spill L-asparagine synthetase into the serum, but the correlation between this phenomenon and the specific activity of the enzyme in homogenates of the tumor was imperfect.
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PMID:L-Asparagine synthetase in serum as a marker for neoplasia. 1 81

Homogeneols L-asparaginase with anti-lymphoma activity was prepared from Vibrio succinogenes, an anaerobic bacterium from the bovine rumen. An overall yield of pure L-asparaginase of 40 to 45% and a specific activity of 200 +/- 2 IU per mg of protein was obtained. The pure enzyme can be stored at -20 degrees for at least 3 months with no loss of activity. The isoelectric point of the L-asparaginase is 8.74. No carbohydrate, phosphorus, tryptophan, disulfide, or sulfhydryl groups were detected. The enzyme has a molecular weight of 146,000 and a subunit weight of approximately 37,000. The Km of the enzyme for L-asparagine is 4.78 X 10(-5) M and the pH optimum of the L-asparaginase reaction is 7.3. D-Asparagine was hydrolyzed at 6.5% of the rate found with the L isomer. L-Glutamine and a variety of other amides were not hydrolyzed at significant rates; the activity of the enzyme for L-glutamine was 130- to 600-fold less than that of other therapeutically effective L-asparaginases of bacterial origin. The L-asparaginase from V. succinogenes is immunologically distinct from the L-asparaginase (EC-2) of Escherichia coli.
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PMID:Purification and characterization of L-asparaginase with anti-lymphoma activity from Vibrio succinogenes. 1 Dec 11

Pseudomonas ovalis produces L-glutaminase and L-asparaginase activities simultaneously upon induction by L-glutamine or L-asparagin in the growth medium. Both activities are confined to the cell during active growth and are not released into the medium. The apparent Km values are 1.4 X 10(-2) M and 6 X 10(-3) M for L-glutamine and L-asparagine substrates, respectively. Induction of both activities is substantially favoured in media with initial pH values higher than 7. In buffered yeast extract L-asparagine medium, significant amounts of L-glutaminase and L-asparaginase activities appeared towards the end of the exponential phase and along the stationary phase. The process of enzyme formation showed a firm link to the cell active growth, as evidenced by the use of growth inhibitors.
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PMID:Kinetics and properties of L-glutaminase and L-asparaginase activities of Pseudomonas ovalis. 1 88


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