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)

Homogenous deamidase AG from Pseudomonas fluorescens AG was found to be a glycoprotein with molecular weight of about 13,000 daltons. The molecule consists apparently of four similar or identic subunits with molecular weight of about 30,000 daltons. The amino acid composition, N-terminal amino acids, the amount of chymotryptic peptides, containing 14C-carboxymethyl cysteine were studied. The enzyme exhibited distinct antitumoral effect on cells of Burkitt's lymphoma, sensitive to asparaginase, but did not exhibit marked cytotoxic action on cells of human ovarium cancer CaOV line, resistant to asparaginases.
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PMID:[Physico-chemical properties of deamidase AG from Pseudomonas fluorescens AG possessing antitumor activity]. 41 Dec 53

Deamidase AG (asparaginase-glutaminase) from Pseudomonas fluorescens AG was shown to hydrolyze 1-glutamine and 1-asparagine highly effectively. Besides, the enzyme exhibited the rather high rate of deamidation of D-asparagine and D-glutamine (70% and 100%, respectively), Nalpha-butyl asparagine (63%) and among peptides -- of glycyl-L-asparagine (40%). L-glutamic acid gamma-methyl ester was hydrolyzed only slightly (5%). Effect of several substrate analogues on the deamidase AG activity was studied as well. Albiciine (alpha-amino-beta-ureide propionic acid) proved to be the strongest inhibitor (100%). Beta-Methyl aspartic acid, S-carbamoyl cysteine, alpha-ketoglutaric acid showed the slight inhibitory effect (20%). Amount of active centres per enzyme molecule was estimated by means of 14C-albiciine. Deamidase AG had apparently only one active centre. In estimation of relationship between the rate of reaction and substrate (L-asparagine) concentration, the reaction was found to follow Michaelis-Menten kinetics, K(m) = 4.5 with 10-4 M.
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PMID:[Substrate specificity, inhibitors and kinetics of deamidase AG (asparaginase-glutaminase) from Pseudomonas fluorescens AG]. 41 63

The L-cyst(e)ine requirements of normal and malignant cells are reviewed and expanded within the context of establishing whether the measurement of gamma-cystathionase levels constitutes a predictive test for tumor sensitivity to L-cyst(e)ine depletion. The ability of both purified L-cysteine desulfhydrase and gamma-cystathionase to inhibit the growth of the L-cystine-dependent L1210 leukemia in culture is presented, as well as approaches to circumvent the limitations of these enzymes for in vivo therapy. The ability of proparagylglycine to inhibit L-cysteine biosynthesis in vivo is reviewed for its possible use in combination therapy. In addition, the ability of poly D,L-alanine modification of Escherichia coli L-asparaginase to increase the plasma half-life in mice tenfold as well as to decrease the immunogenicity of the enzyme is presented.
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PMID:L-cyst(e)ine requirements of malignant cells and progress toward depletion therapy. 46 47

The absorption spectra of trinitrophenyl derivatives of poly(L-lysine) and L-asparaginase undergo irreversible changes in the presence of KBH4. The spectra of trinitrophenyl derivatives of N-acetyl-L-lysine and N-acetyl-L-cysteine are also affected by the addition of the reducing agent. A broad absorption band with a maximum at 426 nm appears in the presence of low concentrations of borohydride with a concomitant decrease in absorbance of the 346 nm band which is characteristic of 1-substituted 2,4,6-trinitrophenyl compounds. In the presence of higher concentrations of KBH4 the long wavelength band becomes less broad as the maximum is shifted to 410 nm and the 346 nm band completely disappears. Similar spectral changes were observed in the presence of Na2SO3 although these were reversible upon removal of the sulfite by dialysis. Based on the spectral similarities with sulfite and hydroxide adducts, we suggest that the 426 nm maximum represents a 1:1 adduct formed between the trinitrophenyl moiety and a hydride ion while the band at 410 nm is assigned to the 1:2 adduct.
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PMID:A spectrophotometric study of the reaction of boro-hydride with trinitrophenyl derivatives of amino acids and proteins. 84 52

An L-asparaginase producing mesophilic fungus Cylindrocarpon obtusisporum MB-10 was isolated from soil. The constitutive intracellular L-asparaginase from the organism was purified. The enzyme after 65-fold purification with an overall yield of 11% and specific activity of 100 unit.mg-1 seemed to be homogeneous in native, SDS-PAGE and thin layer isoelectric focusing gel. The apparent Mr of the enzyme was 216,000, and it constituted four identical subunits. The pI of the enzyme was 5.5. It was a conjugate protein with 37.3% (w/w) carbohydrate. The enzyme was stable to storage at -20 degrees C and to repeated freezing and thawing. The L-asparaginase from the organism was very much specific for L-asparagine and did not hydrolyze D-asparagine and L-glutamine. The pH and temperature optima for the enzyme activity were 7.4 and 37 degrees C, respectively. The Km of the L-asparaginase was found to be 1 x 10(-3)M. Metal ions, such as Zn2+, Fe2+, Cu2+, Hg2+ and Ni2+ potentially inhibited the enzyme activity, while metal chelators like EDTA, CN-, cysteine, etc., enhanced the activity indicating that the enzyme was not a metalloprotein. Its activity was also enhanced in the presence of reduced glutathione but not with dithiothreitol and 2-mercaptoethanol. Differential inhibition of the enzyme activity was observed with iodoacetamide and p-chloromercuribenzoate, thus indicating possible involvement of free-SH group in the enzyme catalysis.
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PMID:Purification and properties of an L-asparaginase from Cylindrocarpon obtusisporum MB-10. 208 Sep 24

In studies on kinetics of thermoinactivation of glutaminase (asparaginase) from Ps. arantiaca BKMB-548 at 50 degrees and pH 7.0 in presence or in absence of L-glutamate the enzyme inactivation was found to obey the first order equation. Both the glutaminase and asparaginase activities decreased at a similar rate. L-Glutamate stabilized the enzyme due to direct interaction with its molecule. Stability of the complex formed was evaluated quantitatively. L-Glutamate reacted apparently with a specific site on the surface of the enzyme molecule; Kdiss was 0.42 +/- 0.03 mM at pH 7.0 and 50 degrees. No cooperative effect was found. L-Aspartate protected the enzyme completely; stabilizing effects of L-cysteine, L-serine and glycine were similar to the effect of L-glutamate (94%, 84%, 83% and 82%, respectively). At the same time, glutarate, succinate, alpha-ketobutyrate, alpha-ketoglutarate, gamma-aminobutyrate and N-benzoyl glutamate did not exhibit the stabilization effect. The data obtained suggest that the high stabilizing effect might exhibit only the substances containing simultaneously free alpha-NH2 and alpha-COOH groups in a molecule, whereas presence of COOH groups at beta--or gamma-carbon atoms was not essential for the stabilizing effect.
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PMID:[Thermostabilization of glutamin(asparagin)ase from Pseudomonas aurantica BKMB-548]. 402 28

The relationship between conformation change and activity of E. coli L-asparaginase has been studied with circular dichroism spectra and microcaloric methods. In many papers, it has been pointed out that the active site of L-asparaginase is closely related to tyrosyl residues. The present authors have studied the effects of L-cysteine on the activity and the conformation of L-asparaginase with UV difference spectra and kinetic methods. Moreover, we have studied the space arrangement of tyrosyl residues in the enzyme molecule. The results show that every enzyme molecule contains about 56 tyrosyl residues, 20 of which are in the hydrophobic core of the enzyme molecule, another 20 at the surface of the enzyme molecule, and the rest in the rifts and hollows of the enzyme molecule. Meanwhile, further study has also been made to determine the relationship between the changes of the enzyme activity and the ionization of tyrosyl residues as well as their chemical modification. By Zou Chenglu's graphical method we have proved that two tyrosyl residues at the surface of the enzyme molecule are the essential groups.
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PMID:Tyrosine micro-region of E. coli L-asparaginase. 702 10

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

The dramatic clinical responses to L-asparaginase led to renewed interest in other enzymes that might be effective antitumor agents. Biochemical and nutritional studies on animal and human tumors have shown that enzymatic depletion of glutamine, arginine, cysteine, citrulline, and serine could have selective cytotoxicity for some tumors. Several glutaminase-asparaginase enzymes have antitumor activity in animals and man. These enzymes are currently in phase I trials. Arginine-depleting enzymes with suitable properties of therapy have been developed and are in preclinical study. Enzymes have not yet been found that can adequately deplete circulating levels of cysteine, citrulline, or serine for treatment of cancer.
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PMID:Enzyme therapy of cancer, future studies. 734 58

L-Asparaginase was extracted from Candida utilis cells using various reducing agents, 2-mercaptoethanol, dithiothreitol, or cysteine. The extraction of the enzyme depended upon the kind and concentration of reducing agents, temperature, time of incubation, and pH of buffer used. The enzyme was typically extracted by incubating the cells at 50 degrees C for 4 h in extraction solution containing 20 mM 2-mercaptoethanol in 20 mM potassium phosphate buffer (pH 7.0). The enzyme can be extracted from either cell precipitate or cell culture broth. The yeast cells were viable after extraction of L-asparaginase.
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PMID:Extraction of extracellular L-asparaginase from Candida utilis. 777 45


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