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)

1. L-Asparaginase has been isolated from aerobically grown Escherichia coli 055:B5 and purified about 140-fold in a three-step procedure involving acidification to pH 4.5, ammonium sulphate fractionation and column chromatography on DEAE-Sephadex A-50. The activity of the preparation is 140 U/mg protein. 2. The enzyme acts within a broad pH range (pH 5-9) and is affected neither by PCMB, N-ethylmaleimide nor metal ions. 3. Molecular weight of the isolated asparaginase is 130 000.
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PMID:Purification and properties of L-asparaginase EC-2 from Escherichia coli 055:B5. 1 56

L-asparaginase was extracted from whole cells of Streptomyces karnatakensis by different procedures, including cell disintegration by ultra sonic waves and grinding with alumina. The specific activity of the enzyme in crude extracts was much lower than that in while cells. Optimum activity of the enzyme in crude extracts was obtained after an incubation time of 30 min at 38 degrees C in the presence of 16 micromole substrate/ml reaction mixture; the enzyme has an apparent Km value of 3.5 x 10(-3) M. The enzyme was inhibited by PCMB, indicating a requirement for a free sulfhydryl group. A competitive type of inhibition was noticed with D1-aspartic and a feed back type of inhibition was noticed with L-cysteine. The enzyme showed stereospecificity for L-asparagine, however, some activity was noticed with the D-isomer. This was discussed in terms of the biosynthesis of an isomerase.
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PMID:Properties of L-asparaginase in cell-free extracts of Streptomyces karnatakensis. 710 40

An L-asparaginase produced by Pseudomonas stutzeri MB-405 was isolated and characterized. After initial ammonium sulfate fractionation, the enzyme was purified by consecutive column chromatography on Sephadex G-100, Ca-hydroxylapatite, and DEAE-Sephadex A-50. The 665.5-fold purified enzyme thus obtained has the specific activity of 732.3 units mg protein-1 with an overall recovery of 27.2%. The apparent M(r) of the enzyme under nondenaturing and denaturing conditions was 34 kDa and 33 kDa respectively, and the isoelectric point was 6.38 +/- 0.02. It displayed optimum activity at pH 9.0 and 37 degrees C. The enzyme was very specific for L-asparagine and did not hydrolyze L-glutaminate. The Km of the L-asparaginase was found to be 1.45 x 10(-4) M towards L-asparagine and was competitively inhibited by 5-diazo-4-oxo-L- norvaline (DONV) with a Ki of 0.03 mM. Metal ions such as Mn2+, Zn2+, Hg2+, Fe3+, Ni2+, and Cd2+ potentially inhibited the enzyme activity. The activity was enhanced in the presence of thiol-protecting reagents such as DTT, 2-ME, and glutathione (reduced), but inhibited by PCMB and iodoacetamide. The tumor inhibition study with Dalton's lymphoma tumor cells in vivo indicated that this enzyme possesses antitumor properties.
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PMID:Purification, characterization and antitumor activity of L-asparaginase isolated from Pseudomonas stutzeri MB-405. 776 57