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)

L-asparaginase from Escherichia coli is an important enzyme widely used in leukemia treatment under the trade name Elspar. Up to now, however, the aspects of its stability and storage has not been studied in detail. The aim of this work is to analyze the factors that could interfere in the enzyme's stability. The enzymatic activity was found to be stable in wide pH range (4.5-11.5), showing a slight increase in activity and stability in alkaline pHs, which indicates a more stable conformation of the molecule. The enzyme proved to have a high activity restoration capacity when submitted to temperatures of 65 degrees C, in pH 8.6 buffer and, surprisingly, in physiologic solution. This suggests a positive effect of sodium ions on such restoration capacity. Stability was high in different diluents used as parenteral solutions and in recipients used in medical practice without significant loss of activity for at least 7 days. These results lead us to conclude that the enzyme has a high stability after the lyophilized form has been reconstituted (at least 7 days), since the necessary precautions are taken in terms of sterile manipulation and if it is stored in a suitable parenteral vehicle under low temperature (about 8 degrees C).
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PMID:Stability of L-asparaginase: an enzyme used in leukemia treatment. 1074 19

Systemic oncologic therapies can cause multiple emergency situations. There are, however, two unique emergencies directly related to chemotherapy administration: drug extravasation and hypersensitivity reactions (HSRs). Most drugs can cause varying degrees of local tissue injury when extravasated. The medical management of extravasation is based on proper maintenance of the intravenous line, application of local cooling or warming for certain extravasations, and the use of antidotes to prevent the local toxic action of the extravasated drug. Antidotes that appear useful include hyaluronidase (for vinca alkaloids, epipodophyllotoxins, and paclitaxel), sodium thiosulfate (for mechlorethamine and cisplatin), and dimethylsulfoxide (DMSO) (for anthracyclines and mitomycin C). HSRs, another potential adverse effect of chemotherapy administration, are a major concern for therapy with taxanes and with L-asparaginase, and their administration requires the use of premedication to prevent these reactions. Once a HSR has occurred, therapy may be continued by using an analog drug or by the administration of premedication as prophylaxis, in particular if the reaction was minor. On the other hand, it is also pertinent to become acquainted with the emergencies induced by biological agents, taking into consideration their increasing usages. In addition to interferons and interleukin-2 (IL-2), both of which have been in clinical use for several years, cytokine-toxin fusion proteins (DAB3891L-2) and two monoclonal antibodies (rituximab and trastuzumab) were recently approved for cancer therapy. The distinct toxicity profiles of these agents are reviewed.
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PMID:Systemic therapy emergencies. 1086 22

A 15-year-old boy with T-cell acute lymphoblastic leukemia (ALL) (FAB L1), diagnosed in 1995, received combination chemotherapy consisting of 6 weeks of induction (vincristine, epirubicin, L-asparaginase, prednisolone) and 2 weeks of consolidation (cytosine arabinosides, etoposide). After achieving remission, for further maintenance of remission, he was treated with 14 cycles of intensive chemotherapy consisting of 6-MP, 10 mg/kg orally on the first 4 days, and cyclophosphamide, 1200 mg/m2, vincristine, 1.5 mg/m2, epirubicin, 15 mg/m2, and cytosine arabinoside, 40 mg/m2, intravenously on days 4, 11, 39, and 40, respectively. On day 18 of each cycle, he received intravenous methotrexate (MTX) infusion in a total dose of 150 mg/m2 plus oral leucovorin (30 mg/m2 ) rescue 36 h after starting MTX therapy. In addition, oral trimethoprim-sulfamethoxazole was given regularly to prevent Pneumocystis carinii infection. The patient achieved remission during the first course of treatment, but 8 months later the disease relapsed. He then received four doses of MTX (800 mg intravenously) plus leucovorin rescue in the following 4 months. During the last MTX therapy, small hemorrhagic bullae were found on the lateral side of the right ankle, but subsided after a few days. Due to partial remission of the disease, he was admitted again in January 1999 for high-dose MTX therapy. An initial hemogram on admission revealed hemoglobin 7.2 g/dL, white cell count 15,200/mm3, platelet count 153/mm3, blood creatinine 0.5 mg/dL, and alanine leucine aminotransferase (ALT) 20 U/L. He received 8500 mg of MTX (5000 mg/m2 ) as a continuous intravenous infusion for 24 h. Thirty-six hours after the start of MTX infusion, leucovorin (30 mg, intravenous) rescue was initiated every 6 h for 3 days. Another preventive measure to cover MTX toxicity included aggressive intravenous fluid replacement (4 L/m2 /day) and the addition of 25 meq/L sodium bicarbonate to the intravenous fluid to alkalinize the urine. Concurrent medication included 6-MP (50 mg) once daily and trimethoprim-sulfamethoxazole (120 mg, 600 mg) twice daily every other day. Plasma MTX levels were 52.36 micromol/L 24 h after MTX infusion, 1.87 micromol/L after 48 h, 0.57 micromol/L after 72 h, and 0.41 micromol/L after 96 h. These indicated delayed MTX plasma clearance. The blood creatinine level was mildly elevated from 0.5 mg/dL to 0.7 mg/dL. Thirty-six hours after the administration of MTX, the patient developed an erythematous painful swelling on the right middle finger. The erythema, with subsequent large bulla formation, progressed to all the fingers, toes, palms, and the soles of the feet. Some erythematous to hemorrhagic papules also appeared on the bilateral elbows. Subsequently, diffuse tender erythema with extensive erosions and focal tiny pustules developed on the back, abdomen, proximal extremities, and face (Fig. 1a,b). A positive Nikolsky's sign was also present. A biopsy specimen of the right dorsal hand lesion revealed parakeratosis, detached acanthotic epidermis with scattered necrotic keratinocytes, dyskeratotic cells and nuclear atypia, neutrophilic exocytosis, and many neutrophils in the papillary dermis (Fig. 2). The skin condition deteriorated rapidly. Toxic epidermal necrolysis-like lesions involved 90% of the total body surface on the fifth day after MTX infusion. Mucositis, diarrhea, involuntary tremor, fever, and chills were noted. The patient was then sent to the burn unit for intensive skin care. Ten days after MTX therapy, profound agranulocytosis and thrombocytopenia (white cell count 100/mm3, platelets 14,000/mm3, and hemoglobin 5.6 g/dL) were found. The patient was then started on granulocyte colony stimulation factor (G-CSF, 5 microg/kg/day), but his general condition deteriorated rapidly and he died 6 days later due to septic shock and multiple organ failure.
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PMID:Toxic epidermal necrolysis following combination of methotrexate and trimethoprim-sulfamethoxazole. 1097 34

A new protocol for the stabilization of the quaternary structure of multimeric enzymes has been attempted using as model enzyme (tetrameric) L-asparaginase from Escherichia coli. Such strategy is based upon multisubunit covalent immobilization of the enzyme onto activated supports (agarose-glutaraldehyde). Supports activated with different densities of reactive groups were used; the higher the density of groups, the higher the stabilization attained. However, because of the complexity of that enzyme, even the use of the highest densities of reactive groups was not enough to encompass all four subunits in the immobilization process. Therefore, a further chemical intersubunit cross-linking with aldehyde-dextran was pursued; these derivatives displayed a fully stabilized multimeric structure. In fact, boiling the modified enzyme derivative in the presence of sodium dodecyl sulfate and beta-mercaptoethanol did not lead to release of any enzyme subunit into the medium. Such a derivative, prepared under optimal conditions, retained ca. 40% of the intrinsic activity of the free enzyme and was also functionally stabilized, with thermostabilization enhancements of ca. 3 orders of magnitude when compared with its soluble counterpart. This type of derivative may be appropriate for extracorporeal devices in the clinical treatment of acute leukemia and might thus bring about inherent advantages in that all subunits are covalently bound to the support, with a longer half-life and a virtually nil risk of subunit release into the circulating blood stream.
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PMID:Structural and functional stabilization of L-asparaginase via multisubunit immobilization onto highly activated supports. 1138 76

In the present paper, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) nanocapsules were prepared by a double emulsion-solvent evaporation procedure (w/o/ w) for the encapsulation of model enzymes (L-asparaginase, catalase, glucose oxidase) and bovine serum albumin. To increase the encapsulation efficiency and activity of the encapsulated enzyme, numerous modifications were made in the compositions of the phases of double emulsion. For the preparation of low molecular weight PHBV, the polymer was treated with sodium borohydride. A 14-fold decrease in molecular weight (from 297000 to 21000) was observed upon 4 h of incubation. Although the amount of encapsulated protein was not increased, the enzyme activity increased upon use of low molecular weight PHBV, indicating that these nanocapsules have a higher permeability to solutes (reactants and products). The adjustment of the second water phase to the isoelectric point of the proteins significantly increased the encapsulation yields of catalase, L-asparaginase and BSA. Likewise, polyethylene glycol coupling significantly increased the entrapment efficiency as well as the activity of catalase and L-asparaginase. A combination of the various optimum preparation conditions further increased the encapsulated catalase activity (about six-fold) in comparison to the initial basic conditions (with no modification and no isoelectric point adjustment).
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PMID:Poly(hydroxybutyrate-co-hydroxyvalerate) nanocapsules as enzyme carriers for cancer therapy: an in vitro study. 1202 2

Asparaginase production by a mesophilic strain of Erwinia sp. was examined; the maximum of activity was found at 40 degrees C and pH 8.5. Among the various carbon sources, mannitol was shown to be the best for production of activity. Inorganic nitrogen sources were better than the organic ones. The enzyme activity was not inhibited by 10 mmol/L metal ions (Na+, K+, Mg2+, Ca2+, Ba2+, Co2+, Ni2+, Zn2+); the activity was strongly inhibited by addition of EDTA. L-Arginine, DL-alanine, L-asparagine and L-glutamine stimulated the L-asparaginase production by 3.9, 1.7, 4.3 and 4.0 fold, respectively. The combination of L-arginine, L-asparagine and L-glutamine synergistically stimulated the asparaginase up to 5.8 fold.
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PMID:Production and properties of asparaginase from a new Erwinia sp. 1250 89

The crystal structure of the Escherichia coli enzyme (EcAIII) with isoaspartyl dipeptidase and L-asparaginase activity has been solved and refined to a resolution of 1.65 angstroms, with crystallographic R-factor and Rfree values of 0.178 and 0.209, respectively. EcAIII belongs to the family of N-terminal hydrolases. The amino-acid sequence of EcAIII is homologous to those of putative asparaginases from plants. The structure of EcAIII is similar to the structures of glycosylasparaginases. The mature and catalytically active form of EcAIII is a heterotetramer consisting of two alpha-subunits and two beta-subunits. Both of the equivalent active sites present in the EcAIII tetramer is assisted by a metal-binding site. The metal cations, modelled here as Na+, have not previously been observed in glycosylasparaginases. This reported structure helps to explain the inability of EcAIII and other plant-type asparaginases to hydrolyze N4-(beta-N-acetylglucosaminyl)-L-asparagine, the substrate of glycosylasparaginases.
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PMID:Structure of the isoaspartyl peptidase with L-asparaginase activity from Escherichia coli. 1515 92

A strategy, termed alanine-scanning mutagenesis, was used to identify the amino acid residues which are critical to the antigenicity of Escherichia coli L-asparaginase (L-ASP). Three continuous alkaline residues, 195RKH197, were mutated to Ala selectively. Four mutant recombinant L-ASPs were constructed and expressed in E. coli, and then purified. The purified mutants showed a single band by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and were more than 95% pure by reverse high-performance liquid chromatography. The activities of wild-type and mL-ASPs in the fermentative medium were all about 130 U/mL. The change from 195RKH197 to 195AAA197 reduced the antigenicity of the enzyme greatly as shown in competition enzyme-linked immunosorbent assay using polyclonal antibodies raised against the wild-type L-ASP from rabbits. The results show that residues 195RKH197 of E. coli L-ASP are critical to its antigenicity.
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PMID:Probing the antigenicity of E. coli L-asparaginase by mutational analysis. 1669 Oct 7

In plants, specialized enzymes are required to catalyze the release of ammonia from asparagine, which is the main nitrogen-relocation molecule in these organisms. In addition, K+-independent plant asparaginases are also active in splitting the aberrant isoaspartyl peptide bonds, which makes these proteins important for seed viability and germination. Here, we present the crystal structure of potassium-independent L-asparaginase from yellow lupine (LlA) and confirm the classification of this group of enzymes in the family of Ntn-hydrolases. The alpha- and beta-subunits that form the mature (alphabeta)2 enzyme arise from autoproteolytic cleavage of two copies of a precursor protein. In common with other Ntn-hydrolases, the (alphabeta) heterodimer has a sandwich-like fold with two beta-sheets flanked by two layers of alpha-helices (alphabetabetaalpha). The nucleophilic Thr193 residue, which is liberated in the autocatalytic event at the N terminus of subunit beta, is part of an active site that is similar to that observed in a homologous bacterial enzyme. An unusual sodium-binding loop of the bacterial protein, necessary for proper positioning of all components of the active site, shows strictly conserved conformation and metal coordination in the plant enzyme. A chloride anion complexed in the LlA structure marks the position of the alpha-carboxylate group of the L-aspartyl substrate/product moiety. Detailed analysis of the active site suggests why the plant enzyme hydrolyzes asparagine and its beta-peptides but is inactive towards substrates accepted by similar Ntn-hydrolases, such as taspase1, an enzyme implicated in some human leukemias. Structural comparisons of LlA and taspase1 provide interesting insights into the role of small inorganic ions in the latter enzyme.
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PMID:Crystal structure of plant asparaginase. 1672 55

Presented here is the first reported case of natural killer (NK)/T-cell lymphoma associated with lactic acidosis (LA) and hypoglycemia. LA and hypoglycemia are rare complications of non-Hodgkin's lymphoma. A 28-year-old male patient with NK/T-cell lymphoma had a relapse after 14 mo of initial remission and was admitted to the hospital because of altered mental status. He developed severe LA (pH, 7.17; lactate, 11.2 mmol/L) and hypoglycemia (42 mg/dL) that was resistant to sodium bicarbonate and glucose infusions. A very brief partial remission was achieved after a cycle of vincristine, dexamethasone, and L-asparaginase was given, but the disease recurred quickly after chemotherapy was discontinued and the patient did not respond to additional chemotherapy. The patient expired at 47 d after relapse. An extensive review of the literature reveals that only 2 of 28 patients have achieved complete remission, and more than 75% of patients died within 1 mo. Furthermore, 90% of previously reported cases had liver involvement. The case described here indicates that non-Hodgkin's lymphoma-induced LA portends a poor prognosis.
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PMID:Fatal lactic acidosis and hypoglycemia in a patient with relapsed natural killer/T-cell lymphoma. 1766 Jan 58


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