Design of experiments and artificial neural network linked genetic algorithm for modeling and optimization of L-asparaginase production by <Emphasis Type="Italic">Aspergillus terreus</Emphasis> MTCC 1782

The sequential optimization strategy for design of an experimental and artificial neural network (ANN) linked genetic algorithm (GA) were applied to evaluate and optimize media component for L-asparaginase production by Aspergillus terreus MTCC 1782 in submerged fermentation. The significant media components identified by Plackett-Burman design (PBD) were fitted into a second order polynomial model (R² = 0.910) and optimized for maximum L-asparaginase production using a five-level central composite design (CCD). A nonlinear model describing the effect of variables on L-asparaginase production was developed (R² = 0.995) and optimized by a back propagation NN linked GA. Ground nut oil cake (GNOC) flour 3.99% (w/v), sodium nitrate (NaNO₃) 1.04%, L-asparagine 1.84%, and sucrose 0.64% were found to be the optimum concentration with a maximum predicted L-asparaginase activity of 36.64 IU/mL using a back propagation NN linked GA. The experimental activity of 36.97 IU/mL obtained using the optimum concentration of media components is close to the predicted L-asparaginase activity of the ANN linked GA.     

Optimization of culture conditions and bench-scale production of L-asparaginase by submerged fermentation of Aspergillus terreus MTCC 1782

Optimization of culture conditions for L-asparaginase production by submerged fermentation of Aspergillus terreus MTCC 1782 was studied using a 3-level central composite design of response surface methodology and artificial neural network linked genetic algorithm. The artificial neural network linked genetic algorithm was found to be more efficient than response surface methodology. The experimental L-asparaginase activity of 43.29 IU/ml was obtained at the optimum culture conditions of temperature 35 degrees C, initial pH 6.3, inoculum size 1% (v/v), agitation rate 140 rpm, and incubation time 58.5 h of the artificial neural network linked genetic algorithm, which was close to the predicted activity of 44.38 IU/ml. Characteristics of L-asparaginase production by A. terreus MTCC 1782 were studied in a 3 L bench-scale bioreactor.     

Biological properties of L-asparaginase preparations from E. coli in cell cultures]

Non-specific cytotoxicity and specific antitumor activity of 5 preparations of L-asparaginase from E. coli were studied. Two cell line, i.e. the asparagine-dependent (Berkitt lymphoma cells) and asparagin-independent (human ovary cancer cells) were used as the test-system. Incorporation of 3H-thimidine into DNA was the criterion of the preparation effect on the cells. Preparation I with the specific activity of 60-90 IU per 1 mg of protein obtained at the first stages of purification had high non-specific cytotoxicity. Preparation II obtained after further purification of preparation I, as well as preparation II without any stabilizer with the specific activity of 200 IU/mg were not inferior to the "Bayer" preparation by their biological properties. Addition of L-asparaginase to the preparation as a stabilizer of excessive glycine (preparation IV) increased its non-specific cytotoxicity and interfered with the study of its properties in the cell systems. Mannitol (preparation V) had no effect on the biological activity of L-asparaginase preparation.     

Determination of parameters for enzyme therapy using L-asparaginase entrapped in canine erythrocytes

The antitumor agent L-asparaginase was entrapped in canine erythrocytes by a single dialysis encapsulation (efficiency mean = 30%). Concentration of asparaginase in carrier cells was about 240 IU/ml, with an average of 62% cell recovery. Use of a double dialysis procedure increased the L-asparaginase concentration within carrier cells to 530 IU/ml, with an overall cell recovery of 53.9%. In vitro efflux experiments showed L-asparaginase-loaded canine carriers were stable at both 4 and 37 degrees C for an 18-h period. In vivo cell survival studies showed that carrier cells did circulate and that L-asparaginase had a half-life of 6.5 days. No evidence suggesting that the enzyme left the cell was found. Carrier cells prepared with [3H]inulin and [14C]sucrose were stored at 4 degrees C for 2 weeks and began to show signs of deterioration after 2 days.     

Purification and characterization of L-asparaginase with anti-lymphoma activity from Vibrio succinogenes.

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.     

Recombinant L-Asparaginase from Zymomonas mobilis: A Potential New Antileukemic Agent Produced in Escherichia coli

L-asparaginase is an enzyme used as a chemotherapeutic agent, mainly for treating acute lymphoblastic leukemia. In this study, the gene of L-asparaginase from Zymomonas mobilis was cloned in pET vectors, fused to a histidine tag, and had its codons optimized. The L-asparaginase was expressed extracellularly and intracellularly (cytoplasmically) in Escherichia coli in far larger quantities than obtained from the microorganism of origin, and sufficient for initial cytotoxicity tests on leukemic cells. The in silico analysis of the protein from Z. mobilis indicated the presence of a signal peptide in the sequence, as well as high identity to other sequences of L-asparaginases with antileukemic activity. The protein was expressed in a bioreactor with a complex culture medium, yielding 0.13 IU/mL extracellular L-asparaginase and 3.6 IU/mL intracellular L-asparaginase after 4 h of induction with IPTG. The cytotoxicity results suggest that recombinant L-asparaginase from Z. mobilis expressed extracellularly in E.coli has a cytotoxic and cytostatic effect on leukemic cells.     

L-Asparaginase Production by Streptomyces griseus

Streptomyces griseus ATCC 10137 synthesizes about 1 IU of L-asparaginase/100 ml of a 4% peptone medium. The enzyme has a pH optimum of 8.5 which is comparable to that of the L-asparaginase derived from Escherichia coli which has antitumor properties.     

Cellular test system for studying the biological properties of preparations with L-asparaginase activity

L-Asparaginase sensitivity and asparagin-deficiency of 5 tumor cell populations, i.e. mouse lymphoma L-1210, LI0-1, LTL, Berkitt lymphoma and human ovary cancer, line CaOv were studied. Radiometric estimation of 3H-thimidine incorporation into the cells of DNA served a criterion of cytotoxicity. "Krasnitin" (FDR) was used as L-asparaginase. The cells of leukemia L-1210, lymphosarcoma LIO-1 and line CaOv were asparagine-independent and non-sensitive to L-asparaginase. The cells of mouse lympholeukemia LTL and the cultures of Berkitt human lymphoma proved to be asparagin-dependent and highly sensitive to L-asparaginase. In concentration of 50 IU/ml the drug inhibited incorporation of 3H-thimidine in the cells of LTL and Berkitt lymphoma by 97-98 and 75-80 per cent respectively. Inhibition of 3H-thimidine incorporation in the cells of LTL and Berkitt lymphoma was more pronounced after incubation with the drug for 8 and 24 hours respectively. Two out of the 5 tumor cell populations were chosen as a result of the study. One of these 2 populations, i.e. the cells of Berkitt lymphoma was asparagin-dependent and highly sensitive to L-asparaginase, the other, i.e. the cells of line CaOv was asparagin-independent and resistant to the specific antitumor effect of the enzyme. The use of a system of these two cell lines provided estimation of the ratio of the specific cytostatic (antitumor activity) and non-specific cytostatic properties in the preparations with L-asparaginase activity.     

Production, isolation, and purification of L-asparaginase from Pseudomonas aeruginosa 50071 using solid-state fermentation

The L-asparaginase (E. C. 3. 5. 1. 1) enzyme was purified to homogeneity from Pseudomonas aeruginosa 50071 cells that were grown on solid-state fermentation. Different purification steps (including ammonium sulfate fractionation followed by separation on Sephadex G-100 gel filtration and CM-Sephadex C50) were applied to the crude culture filtrate to obtain a pure enzyme preparation. The enzyme was purified 106-fold and showed a final specific activity of 1900 IU/mg with a 43% yield. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of the purified enzyme revealed it was one peptide chain with M(r) of 160 kDa. A Lineweaver-Burk analysis showed a K(m) value of 0.147 mM and V(max) of 35.7 IU. The enzyme showed maximum activity at pH 9 when incubated at 37 degrees C for 30 min. The amino acid composition of the purified enzyme was also determined.     

Microbial cell disruption methods for efficient release of enzyme L-asparaginase

Abstract

The efficacy of a simple laboratory method for cell disruption based on the glass bead stirring, sonication, osmotic shock, freezing and grinding, or use of solvents and detergents was assessed in this study, via measurements of the release of total protein and L-asparaginase activity. Three different microbial sources of L-asparaginase were used: Escherichia coli BL21 (DE3), Leucosporidium muscorum, and Aspergillus terreus (CCT 7693). This study adjusted and identified the best procedure for each kind of microorganism. Sonication and glass bead stirring led to obtaining filamentous fungus cell-free extracts containing high concentrations of soluble proteins and specific activity; however, sonication was the best since it obtained 4.61?±?0.12?IU?mg^?1 after 3?min of operation time. Mechanical methods were also the most effective for yeast cell disruption, but sonication was the technique which yielded a higher efficiency releasing 7.3 IUtotal compared to glass bead stirring releasing 2.7 IUtotal at the same operation time. For bacterium, sonication proved to be the best procedure due to getting the highest specific activity (9.01?IU?mg^?1) and total enzyme activity (61.7?IU). The data presented lead to conclude that the mechanical methods appeared to be the most effective for the disintegration of the all microbial cells studies. This is the first report related to the experimental comparison of L-ASNase extraction procedures from different microorganisms, which can also be used for extracting periplasm located enzymes from other organisms.     

Antiproliferative activity of L-asparaginase of Tetrahymena pyriformis on human breast cancer cell lines

Purified L-asparaginase of Tetrahymena pyriformis is a multi-subunit enzyme exhibiting protein kinase activity as well. The enzyme's L-asparaginase activity is affected by its phosphorylation state. Both native and dephosphorylated L-asparaginase show antiproliferative activity on three breast cancer cell lines (T47D, BT20 and MCF-7) and on Walker 256 cells. These cells do not possess measurable L-asparaginase or L-asparagine synthetase activity. When T47D cells are treated for different times with L-asparaginase and then placed in fresh medium, the growth of cells treated for 1, 3, or 6 hours is initiated and parallels control curve, while the growth of cells treated for 24 or 48 hours with L-asparaginase stays at the same inhibitory level (24 h treatment) or continues to drop (48 h treatment). Addition of D-asparagine, a competitive inhibitor of T. pyriformis L-asparaginase, counteracts the antiproliferative activity of L-asparaginase, indicating that L-asparaginase and not the kinase activity is responsible for that effect.     

A fluorometric assay for L-asparaginase activity and monitoring of L-asparaginase therapy

The antineoplastic enzyme L-asparaginase is commonly used for the induction of remission in acute lymphoblastic leukemia (ALL). There is no simple method available for measuring the activity of this highly toxic drug. We incubated L-asparaginase from Erwinia chrysanthemi with L-aspartic acid beta-(7-amido-4-methylcoumarin) and measured the release of 7-amino-4-methylcoumarin fluorometrically for 30-300 min. The rate of the hydrolysis of the substrate was linear over a 50-fold range of the concentration of the enzyme. With increasing substrate concentration, the enzyme showed a saturable kinetic pattern with V(max) of 0.547 (SD 0.059) microM/min/mg of enzyme (n = 3) and Km of 0.302 (SD 0.095) mM (n = 3). This assay enables rapid analysis of L-asparaginase activity in biological samples and it can be used, for example, for monitoring of L-asparaginase activity in serum of ALL patients during their L-asparaginase therapy.     

Effects of L-asparaginase on rat embryonic development and yolk sac membrane in vitro

A comparative analysis of the teratogenic effects of L-asparaginase on 10.5- and 11.5-day rat embryos after 24 and 48 hours of exposure in vitro, respectively, were performed. Several medium concentrations of L-asparaginase (0.05, 0.25, and 1.5 IU/ml) were tested in both embryo series. Resulting embryos were submitted to morphological studies in a search for a specific route of pathogenesis. Morphological alterations of the visceral yolk sac were also studied to investigate its contribution to L-asparaginase teratogenicity in rats. Main embryonic malformations (open truncal neural tube, open encephalic vesicles, anophthalmia, lack of inversion, abnormal frontolateral protrusions, great vascular dilations at the cephalic level) and developmental retardation were already generated after the first 24 hours of culture (embryos of 10.5 days) and presented a dose-response relationship. Vascular dilations and neurulation disturbances seemed to be related to an early mesenchyme deficiency. Reduced number of mesenchymal cells was more evident in embryos of 10.5 days than those of 11.5 days, suggesting the existence of a later compensatory mechanism of cellular proliferation in the older embryo. Visceral yolk-sac endodermal cells at both embryonic stages were greatly deformed and enlarged by an increase of the high electron-dense vacuolar system. Therefore, both a blockage of the processes of lysosomal digestion and derived trophic deficiencies probably existed. A double teratogenic mechanism for L-asparaginase is postulated: a direct action mainly in younger embryos (before invagination of the embryo into the yolk sac) and a yolk sac-mediated one.     

L-asparaginase-induced apoptosis in ALL cells involves IP3 receptor signaling

L-asparaginase treatment is used in the clinic to treat acute lymphoblastic leukemia (ALL) patients. Lee et al. (2019, Blood 133:2222-2232) demonstrated that L-asparaginase induces apoptosis by activating inositol 1,4,5-trisphosphate (IP₃)-induced Ca²⁺ signaling in a Huntingin-associated protein 1 (HAP1)-dependent manner. Moreover, HAP1 levels inversely correlate with the sensitivity of the ALL cells to L-asparaginase. HAP1 can therefore be used as biomarker for evaluating L-asparaginase resistance.     

Molecular characterization of the soybean L-asparaginase gene induced by low temperature stress

L-asparaginase (EC 3.5.1.1) catalyzes the hydrolysis of the amide group of L-asparagine, releasing aspartate and NH4+. We isolated a low temperature-inducible cDNA sequence encoding L-asparaginase from soybean leaves. The full-length L-asparaginase cDNA, designated GmASP1, contains an open reading frame of 1,258 bp coding for a protein of 326 amino acids. Genomic DNA blotting and fluorescence in situ hybridization showed that the soybean genome has two copies of GmASP1. GmASP1 mRNA was induced by low temperature, ABA and NaCl, but not by heat shock or drought stress. E. coli cells expressing recombinant GmASP1 had 3-fold increased L-asparaginase activity. A possible function of L-asparaginase in the early response to low temperature stress is discussed.     

Genetic and physiological relationships between L-asparaginase I and asparaginase II in Saccharomyces cerevisiae.

The cistron that codes for L-asparaginase I in Saccharomyces cerevisiae (aspl) is not genetically linked to either of the cistrons coding for expression of asparaginase II (asp2 and asp3). Cells containing different combinations of theses enzymes grow at different rates in media in which L-asparagine or D-asparagine is the only source of nitrogen for cell replication. Cells lacking L-asparaginase I but possessing asparaginase II grow more rapidly in medium containing D-asparagine as a nitrogen source than cells containing both enzymes, even though D-asparagine is not a substrate of L-asparaginase I. These results indicate that L-asparaginase I and asparaginase II interact in some way to regulate the utilization of asparagine as a nitrogen source for cell growth.     

L-asparaginase: a promising chemotherapeutic agent

This article comprises detailed information about L-asparaginase, encompassing topics such as microbial and plant sources of L-asparaginase, treatment with L-asparaginase, mechanism of action of L-asparaginase, production, purification, properties, expression and characteristics of l-asparaginase along with information about studies on the structure of L-asparaginase. Although L-asparaginase has been reviewed by Savitri and Azmi (2003), our effort has been to include recent and updated information about the enzyme covering new aspects such as structural modification and immobilization of L-asparaginase, recombinant L-asparaginase, resistance to L-asparaginase, methods of assay of L-asparagine and L-asparaginase activity using the biosensor approach, L-asparaginase activity in soil and the factors affecting it. Also, side-effects of L-asparaginase treatment in acute lymphoblastic leukemia (ALL) have been discussed in the current review. L-asparaginase has been and is still one of the most widely studied therapeutic enzymes by researchers and scientists worldwide.     

Fermentation Kinetics and Continuous Process of L-Asparaginase Production

For the purpose of obtaining L-asparaginase in quantities from Erwinia aroideae, cell growth and enzyme formation were investigated in both batch and continuous fermentation. Using yeast extract as a growth-limiting substrate, the relationship between specific growth rate and substrate concentration was found to fit the Monod equation. The optimum temperature for enzyme production was 24 C, although cell growth was higher at 28 C. The enzyme yield reached its maximum of 4 IU/ml during the negative acceleration growth phase which occurs just prior to stationary growth. Compared to batch fermentations, the continuous fermentation process gave a lower enzyme yield except when the fermentation was conducted at a dilution rate of 0.1 hr(-1). The graphical method frequently used for prediction of continuous fermentation does not apply to L-asparaginase production by E. aroideae. The optimum temperature for enzyme production in continuous process was 24 C, which was the same as in batch process. Increasing the temperature from 24 to 28 C resulted in a 20% loss of enzyme yield.     

Effect of corticoid therapy on growth hormone secretion

Exogenous corticoids are known to be potent inhibitors of linear growth in children. We investigated the mechanisms underlying growth failure by evaluating growth hormone (GH) release during short-term high-dose prednisone treatment (40 mg/m2/day given orally in 3 divided doses) and 7 days after steroid withdrawal in 7 prepubertal children (4 males, 3 females, age range 3-12 years), affected by acute lymphoblastic leukemia. Patients also received weekly administrations of vincristine (1.5 mg/m2 i.v.), daunomycin (20 mg/m2 i.v.) and L-asparaginase (6,000 IU/m2 i.m.). Corticoid therapy suppressed GH secretion during deep sleep as well as in response to arginine, insulin and GH-releasing hormone (GHRH) administration. A significant recovery of GH responsiveness after drug discontinuation was observed during deep sleep (14.03 +/- 3.47 vs. 1.49 +/- 0.43 ng/ml, p less than 0.025) as well as in response to arginine (13.63 +/- 2.73 vs. 4.95 +/- 1.54 ng/ml, p less than 0.025) and GHRH (32.62 +/- 4.59 vs. 7.27 +/- 3.52 ng/ml, p less than 0.005) but not to insulin (7.12 +/- 0.88 vs. 4.47 +/- 0.96 ng/ml, p = NS). Insulin-like growth factor 1 levels during deep sleep (0.61 +/- 0.13 IU/ml/min) were found to be low in the course of steroid therapy and did not increase after drug withdrawal (0.41 +/- 0.07 IU/ml/min). Our preliminary data suggest that recovery of adrenergic response to insulin does not immediately follow corticosteroid discontinuation.     

L-Asparaginase Production by the Rumen Anaerobe Vibrio succinogenes

The rumen anaerobe Vibrio succinogenes possesses a constitutive L-asparaginase. The amount of enzyme produced is affected by the compound supplied to the organism to generate the fumaric acid it requires as a terminal electron acceptor. When nitrate is provided as the terminal electron acceptor, the amount of enzyme produced is affected by the compound provided to satisfy the nutritional requirement of the organism for succinic acid. Specific activities of up to 8.4 IU/mg of protein in cell-free extracts have been obtained. This specific activity is higher than has been previously reported for any organism. The enzyme has an apparent K(m) of 1.7 x 10(-5) M and low activity towards L-glutamine when assayed at pH 8.5.