Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

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

It has been demonstrated that the activity of asparaginase A from Ps. fluorescens AG is completely inhibited by 10(-4) M p-chloromercurybenzoate and by 70-85% by Zn2+, Ca2+ and Cu2+ (2.10(-2) M). Iodoacetate, iodoacetamide, N-ethylimide of maleic acid and 5,5'-dithiobis-(2-nitrobenzoic acid) do not decrease the enzyme activity. Dithiothreitol and beta-mercaptoethanol reactivate the enzyme. L-asparagine, the substrate of asparaginase, protects the enzyme in a large degree against the inhibitory action of p-chloromercurybenzoate. p-chloromercurybenzoate induces a sharp increase in the asparaginase inactivation rate at acidic (6.5--5.5) and alkaline (7.5-8.5) values of pH. The enzyme modification by p-chloromercurybenzoate does not change the Km value for L-asparagine, but decreases Vmax. Thus it may be assumed, that asparaginase from Ps. fluorescens AG contains sulfhydryl groups essential for the enzyme activity.
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PMID:[Sulfhydryl groups of L-asparaginase A from Pseudomonas fluorescens AG]. 1 36

Electrolyte disturbances in leukemia can be the result of the disease process or drug therapy. One group of electrolyte abnormalities is related to the stage of the leukemic process. Included in this group are newly diagnosed patients who may show elevated serum potassium, phosphorus, and magnesium--a result of their release from malignant cells after cytotoxic therapy or their accumulation due to urate nephropathy. Patients in remission usually have normal serum electrolyte concentrations, but acute leukemia patients during relapse may have hypokalemia, hypophosphatemia, and hypomagnesemia. This imbalance may be related to cellular uptake of these electrolytes in the presence of inadequate dietary intake. Other factors contributing to electrolyte derangements, and related to the leukemic process, include hyponatremia and hypochloremia secondary to the SIADH, hypokalemia in acute monocytic or acute myelomonocytic leukemia due to lysozyme-induced tubular damage, hypercalcemia possibly secondary to leukemic infiltration of bone or parathyroid glands (with PTH release), or production of a PTH-like substance by leukemic cells. Nonspecific factors related to the disease process which may aggravate the electrolyte imbalance include gastrointestinal loss through nausea, vomiting, and malnutrition. The drug-related electrolyte abnormalities include cyclophosphamide- and vincristine-induced SIADH; decreased serum sodium, chloride, potassium, and calcium concentrations as a result of polymyxin B nephrotoxicity; hypokalemia and hypomagnesemia secondary to amphotericin B; hypocalcemia, hypophosphatemia, and hyperphosphaturia due to L-asparaginase-induced hypoparathyroidism; hypokalemia due to a nonreabsorbable anion effect of antibiotics in the distal tubule or changes in membrane ionic transport of all cells by large doses of antibiotics. Electrolyte disturbance in leukemia thus have a multifactorial pathogenesis which can best be delineated according to the stage of the leukemic process and the drugs being used. Recognition of the cause or causes in a particular patient is essential for an effective approach to management. This review emphasizes the need for routine measurement of serum electrolytes during all phases of the leukemic process.
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PMID:Electrolyte and acid-base disturbances in the management of leukemia. 26 90

We studied the histamine-releasing activity of several antineoplastic drugs on rat pleural and peritoneal mast cells. The drugs tested included the nitrogen mustards cyclophosphamide and ifosfamide, the nitrosourea carmustine, the triazene dacarbazine, the folic acid analogue methotrexate, the pyrimidine analogue cytarabine and fluorouracil, the vinca alkaloids vinblastine, vincristine and Vinorelbine, the epipodophyllotoxins etoposide and teniposide, and the enzyme L-asparaginase. Methotrexate, carmustine, fluorouracil, vinblastine and vincristine failed to elicit histamine release on rat mast cells. All of the other drugs evoked histamine release in both the presence and the absence of extracellular calcium, but ifosfamide, cytarabine and asparaginase induced a much lower release in the absence of this cation. The response elicited by cytarabine and etoposide was much higher in pleural than in peritoneal mast cells. These results indicate that some antineoplastic drugs may directly activate the release of histamine, which could contribute to some of their secondary effects.
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PMID:Non-immunological release of histamine from rat mast cells elicited by antineoplastic agents. 137 74

A 37-year-old female with hypercalcemia presented with lumbago, nausea and vomiting. Peripheral blood (PB) and bone marrow (BM) smears revealed no lymphoblasts on the first admission. The value of parathyroid hormone related protein (PTHrP) was increased and osteoporosis was found in the lumbar vertebrae. After 5 months, diagnosis of acute lymphocytic leukemia (ALL) was made on the evidence that lymphoblasts were found in PB (1%) and in BM (98%). Treatment with vincristine, daunorubicin, prednisolone and L-asparaginase achieved complete remission (CR) and the serum calcium level returned to the normal range. She has maintained CR, and is currently treated with consolidation therapy by cyclophosphamide and methotrexate. Acute leukemia is known to be rarely accompanied with hypercalcemia. This rare case was accompanied with hypercalcemia in acute leukemia. Hypercalcemia appeared to be attributable to the increased bone absorption by PTHrP derived from tumor cells. This important case will help understanding the etiology of hypercalcemia associated with ALL.
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PMID:[Acute lymphocytic leukemia (L1) preceded by hypercalcemia]. 160 17

We report 2 new cases of thrombosis occurring in a cohort of 21 consecutive patients with acute lymphocytic leukemia treated with L-asparaginase (L-ase), 6,000 U/die s.c. or i.m. days 15-21 from start of chemotherapy, according to the GIMEMA LAL 0288 protocol. The first patient died of massive diffuse thromboembolism (thrombosis of sagittal sinus and of suprahepatic veins and pulmonary arteries; multiple hepatic and splenic infarctions) associated with markedly reduced levels of protein C, antithrombin III and plasminogen. In the second patient, portal vein thrombosis developed soon after the completion of L-ase. Antithrombin III was reduced, whereas protein C level was normal. Therapy with fresh frozen plasma and subcutaneous calcium heparin (12,500 U twice daily) proved successful, and 8 days later abdominal echotomography revealed the complete disappearance of the thrombus. The incidence of thrombosis is similar to that previously found in a cohort of consecutive patients treated at our Department with a different schedule and dosage of L-ase administration, and similar to that reported in previous series.
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PMID:Thrombotic complications during L-asparaginase treatment for acute lymphocytic leukemia. 209 99

Most of L-asparaginase activity of Tetrahymena pyriformis was found to be present in microsomal membranes from which it has been purified to homogeneity (Tsirka, S.A.E. and Kyriakidis, D.A. Mol. Cell. Biochem. 83: 147-155, 1988). The native enzyme has a relative molecular weight of approximately 200 kDa, while under denaturing conditions the enzyme exhibits a subunit size of 39 kDa. Aminoacid analysis and an oligopeptide from N-terminal sequence have been determined. Dephosphorylation of L-asparaginase by alkaline phosphatase results in an activation of its catalytic activity. This enzyme also exhibits intrinsic phosphorylation activity with a Km value for ATP of 0.5 mM. Autophosphorylation with [gamma-32P] ATP of purified L-asparaginase results in the phosphorylation of tyrosine residues as well as in loss of its activity. Mg2+ and Ca2+ added together act synergistically to stimulate the kinase activity by more than 160%. The polyamines putrescine, spermidine and spermine activate the kinase approximately 100%, while neither cAMP or cGMP have any effect. These results indicate that this membrane protein with dual L-asparaginase/kinase activity must play an important role in regulating the intracellular levels of L-asparagine in Tetrahymena pyriformis.
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PMID:L-asparaginase of Tetrahymena pyriformis is associated with a kinase activity. 211 26

A 10-year-old boy with leukaemia-associated hypercalcaemia was treated with aminohydroxypropylidene biphosphonate (AHPrBP previously APD) in a total dosage of 60 mg over 5 days, when the condition failed to respond to rehydration and frusemide and no sustained effect was produced by haemodialysis with a calcium (Ca)-free dialysate. Bone films showed no lytic lesions, and AHPrBP, which is a potent inhibitor of osteoclast-mediated bone resorption was well tolerated and induced a rapid and sustained fall in plasma Ca (from 3.42 to 2.07 mM in 5 days). Plasma magnesium and alkaline phosphatase remained normal. The results could have been affected by other drugs [vincristine, cyclophosphamide, zorubicin (Rubidazone) L-asparaginase and prednisone] which were simultaneously administered. However, the observation that: (1) the response curve of plasma Ca was similar to that reported when AHPrBP was used alone, (2) there was complete inhibition of urinary Ca excretion and (3) hypocalcaemia occurred suggests that AHPrBP was the major cause of the reduction in plasma Ca. AHPrBP should be considered a potential therapy for hypercalcaemia in childhood malignancy.
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PMID:Leukaemia-associated hypercalcaemia in a 10-year-old boy: effectiveness of aminohydroxypropylidene biphosphonate. 224 18

Regulation of the asparaginase activity rhythm in L. michotii has previously been shown to be dependent on a reversible phosphorylation process. Asparaginase was isolated as a purified protein complex having self-phosphorylating capacities, which were analyzed. In vivo phosphorylation of asparaginase complex was performed synchronously with the rhythm of asparaginase activity. In vitro self-phosphorylation of asparaginase complex resulted from the activity of an ATP-Mg2+-dependent protein kinase, which phosphorylated protein at threonine residues and was not dependent on cyclic AMP, Ca2+ or calmodulin. Dephosphorylation of this complex was due to a Mg2+-Zn2+-dependent protein phosphatase, molybdate inhibited, the specificity of which, for low-molecular-weight nonprotein phosphoesters, was broad.
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PMID:Reversible self-phosphorylation of asparaginase complex in Leptosphaeria michotii: characterization of associated protein kinase and protein phosphatase activities. 302 34

Twelve dogs with lymphosarcoma and hypercalcemia were treated over a period of 36 months. Signs and laboratory findings were referable to hypercalcemia and azotemia. All dogs were staged, classified histologically, and given cytoreductive chemotherapy, using 5 drugs (vincristine sulfate, cytosine arabinoside, cyclophosphamide, L-asparaginase and prednisone). For azotemia, symptomatic therapy (0.9% NaCl solution and furosemide) was given. Seven dogs responded completely, with marked reduction of lymphadenopathy and return of serum calcium concentration to normal. Median duration of remission in this group was 48 days (range, 14 to 93), and median survival time was 112 days (range, 85 to 153). Five nonresponding dogs had less than 50% reduction in measurable tumor mass, although serum calcium concentration returned to normal. The median survival time for this group was 34 days (range, 23 to 68). Two of the nonresponders died from sepsis and another from disseminated intravascular coagulation. Response to therapy did not appear to be influenced by age, breed, sex, initial calcium concentration, degree of azotemia, or histologic classification.
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PMID:Chemotherapeutic responses in dogs with lymphosarcoma and hypercalcemia. 689 39


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