Purification, characterization and immunogenicity assessment of glutaminase free L-asparaginase from Streptomyces brollosae NEAE-115

Kinetics characterization of a low immunogenic recombinant l-asparaginase from Phaseolus vulgaris with cytotoxic activity against leukemia cells

l-asparaginases play a crucial role in the treatment of acute lymphoblastic leukemia (ALL), a type of cancer that mostly affects children and teenagers. However, it is common for these molecules to cause adverse reactions during treatment. These downsides ignite the search for novel asparaginases to mitigate these problems. Thus, this work aimed to produce and characterize a recombinant asparaginase from Phaseolus vulgaris (Asp-P). In this study, Asp-P was expressed in Escherichia coli with high yields and optimum activity at 40 °C, pH 9.0. The enzyme Km and Vmax values were 7.05 mM and 1027 U/mg, respectively. Asp-P is specific for l-asparagine, showing no activity against l-glutamine and other amino acids. The enzyme showed a higher cytotoxic effect against Raji than K562 cell lines, but only at high concentrations. In silico analysis indicated that Asp-P has lower immunogenicity than a commercial enzyme. Asp-P induced biofilm formation by Candida sp. due to sublethal dose, showing an underexplored potential of asparaginases. The absence of glutaminase activity, lower immunogenicity and optimal activity similar to physiological temperature conditions are characteristics that indicate Asp-P as a potential new commercial enzyme in the treatment of ALL and its underexplored application in the treatment of other diseases.

Production of highly cytotoxic and low immunogenic L-asparaginase from Stenotrophomonas maltophilia EMCC2297

L-asparaginase is an important therapeutic enzyme that is frequently utilized in the chemotherapy regimens of adults as well as pediatric patients with acute lymphoblastic leukemia. However, a high rate of hypersensitivity with prolonged use has limited its utilization. Stenotrophomonas maltophilia (S. maltophilia) EMCC2297 isolate was reported as a novel and promising source for L- asparaginase. The present study aimed at the production, purification, and characterization of L- asparaginase from S. maltophilia EMCC2297 isolate. The microbial production of L-asparaginase by the test isolate could be increased by pre-exposure to chloramphenicol at 200 µg/ml concentration. S. maltophilia EMCC2297 L-asparaginase could be purified to homogeneity by ammonium sulphate precipitation and the purified form obtained by gel exclusion chromatography showed total activity of 96.4375 IU/ml and specific activity of 36.251 IU/mg protein. SDS-PAGE analysis revealed that the purified form of the enzyme is separated at an apparent molecular weight of 17 KDa. Michaelis-Menten constant analysis showed a Km value of 4.16 × 10- 2 M with L-asparagine as substrate and Vmax of 10.67 IU/ml. The antitumor activity of the purified enzyme was evaluated on different cell lines and revealed low IC50 of 2.2 IU/ml and 2.83 IU/ml for Hepatocellular cancer cell line (HepG-2), human leukemia cancer cell line (K-562), respectively whereas no cytotoxic effect could be detected on normal human lung fibroblast cells (MRC-5). However, mice treated with native L-asparaginase showed lower IgG titre compared to commercial L-asparaginase. This study highlights the promising characteristics of this enzyme making it a valuable candidate for further research and development to be an adduct in cancer chemotherapy.

Desirable L-asparaginases for treating cancer and current research trends

Amino acid depletion therapy is a promising approach for cancer treatment. It exploits the differences in the metabolic processes between healthy and cancerous cells. Certain microbial enzymes induce cancer cell apoptosis by removing essential amino acids. L-asparaginase is an enzyme approved by the FDA for the treatment of acute lymphoblastic leukemia. The enzymes currently employed in clinics come from two different sources: Escherichia coli and Erwinia chrysanthemi. Nevertheless, the search for improved enzymes and other sources continues because of several factors, including immunogenicity, in vivo instability, and protease degradation. Before determining whether L-asparaginase is clinically useful, research should consider the Michaelis constant, turnover number, and maximal velocity. The identification of L-asparaginase from microbial sources has been the subject of various studies. The primary goals of this review are to explore the most current approaches used in the search for therapeutically useful L-asparaginases and to establish whether these investigations identified the crucial characteristics of L-asparaginases before declaring their therapeutic potential.

Evaluation of the efficiency of thermostable L-asparaginase from B. licheniformis UDS-5 for acrylamide mitigation during preparation of French fries

A thermostable L-asparaginase was produced from Bacillus licheniformis UDS-5 (GenBank accession number, OP117154). The production conditions were optimized by the Plackett Burman method, followed by the Box Behnken method, where the enzyme production was enhanced up to fourfold. It secreted L-asparaginase optimally in the medium, pH 7, containing 0.5% (w/v) peptone, 1% (w/v) sodium chloride, 0.15% (w/v) beef extract, 0.15% (w/v) yeast extract, 3% (w/v) L-asparagine at 50 °C for 96 h. The enzyme, with a molecular weight of 85 kDa, was purified by ion exchange chromatography and size exclusion chromatography with better purification fold and percent yield. It displayed optimal catalysis at 70 °C in 20 mM Tris-Cl buffer, pH 8. The purified enzyme also exhibited significant salt tolerance too, making it a suitable candidate for the food application. The L-asparaginase was employed at different doses to evaluate its ability to mitigate acrylamide, while preparing French fries without any prior treatment. The salient attributes of B. licheniformis UDS-5 L-asparaginase, such as greater thermal stability, salt stability and acrylamide reduction in starchy foods, highlights its possible application in the food industry.

Strain improvement, artificial intelligence optimization, and sensitivity analysis of asparaginase-mediated acrylamide reduction in sweet potato chips

In recent times, L-asparaginase has emerged as a potential anti-carcinogen through hydrolysis of L-asparagine in the blood for anti-leukemic application, and in carbohydrate-based foods, for acrylamide reduction applications. In this study, Aspergillus sydowii strain UCCM 00124 produced an L-asparaginase with a baseline acrylamide reduction potential of 64.5% in sweet potato chips. Plasma mutagenesis at atmospheric pressure and room temperature (ARTP) was employed to improve L-asparaginase production while artificial neural network embedded with genetic algorithm (ANN-GA) and global sensitivity analysis were used to identify and optimize process conditions for improved acrylamide reduction in sweet potato chips. The ARTP mutagenesis generated a valine-deficient mutant, Val-Asp-S-180-L with 2.5-fold L-asparaginase improvement. The ANN-GA hybrid evolutionary intelligence significantly improved process efficiency to 98.18% under optimized conditions set as 118.6 °C, 726.37 g/L asparagine content, 9.92 µg/mL L-asparaginase, 4.54% NaCl, and soaking time of 15 h without significant changes in sensory properties. The sensitivity index revealed initial asparagine content as the most sensitive parameter to the bioprocess. The enzyme demonstrated significant thermo-stability with Arrhenius deactivation rate constant, Kd, of 0.00562 min-1 and half-life, t1/2, of 123.35 min at 338 K. These conditions are recommended for sustainable healthier, and safer sweet potato chips processing in the food industry.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05757-5.

Characterization of L-asparaginase from Streptomyces koyangensis SK4 with acrylamide-minimizing potential in potato chips

Microbial L-asparaginase is well known for its application in food industries to reduce acrylamide content in fried starchy food. L-asparaginase produced by Arctic actinomycetes Streptomyces koyangensis SK4 was purified and studied for biochemical characterization. The L-asparaginase was purified with a yield of 15.49% and final specific activity of 179.77 IU/mg of protein. The enzyme exhibited a molecular weight of 43 kDa. The optimum pH and temperature for maximum activity of the purified enzyme were 8.5 °C and 40 °C, respectively. The enzyme expressed maximum activity at an incubation period of 30 min and a substrate concentration of 0.06 M. The enzyme has a low Km value of 0.041 M and excellent substrate specificity toward L-asparagine. The enzyme activity was inhibited by metal ions Ba2+ and Hg2+, while Mn2+ and Mg2+ enhanced the activity. The study evaluated the acrylamide reduction potential of L-asparaginase from Streptomyces koyangensis SK4 in potato chips. The blanching plus L-asparaginase treatment of potato slices resulted in a 50% reduction in acrylamide content. The study illustrated an effective acrylamide reduction strategy in potato chips using L-asparaginase from a psychrophilic actinomycete. Besides the acrylamide reduction potential, L-asparaginase from Streptomyces koyangensis SK4 also did not exhibit any glutaminase or urease activity which is an outstanding feature of L-asparaginase to be used as a chemotherapeutic agent.

Production, characterization and techno-economic evaluation of Aspergillus fusant L-asparaginase

Protoplast fusion is one of the most reliable methods of introducing desirable traits into industrially-promising fungal strains. It harnesses the entire genomic repertoire of fusing microorganisms by routing the natural barrier and genetic incompatibility between them. In the present study, the axenic culture of a thermo-halotolerant strain of Aspergillus candidus (Asp-C) produced an anti-leukemic L-asparaginase (L-ASNase) while a xylan-degrading strain of Aspergillus sydowii (Asp-S) produced the acrylamide-reduction type. Protoplast fusion of the wild strains generated Fusant-06 with improved anti-leukemic and acrylamide reduction potentials. Submerged fed-batch fermentation was preferred to batch and continuous modes on the basis of impressive techno-economics. Fusant-06 L-ASNase was purified by PEG/Na⁺ citrate aqueous two-phase system (ATPS) to 146.21-fold and global sensitivity analysis report revealed polymer molecular weight and citrate concentration as major determinants of yield and purification factor, respectively. The enzyme was characterized by molecular weight, amino acid profile, activity and stability to chemical agents. Michaelis-Menten kinetics, evaluated under optimum conditions gave K_m, V_max, K_cat, and K_cat/K_m as 6.67 × 10^-5 M, 1666.67 µmolmin^-1 mg^-1 protein, 3.88 × 10⁴ min^-1 and 5.81 × 10⁸ M^-1.min^-1 respectively. In-vitro cytotoxicity of HL-60 cell lines by Fusant-06 L-ASNase improved significantly from their respective wild strains. Stability of Fusant-06 L-ASNase over a wide range of pH, temperature and NaCl concentration, coupled with its micromolar K_m value, confers commercial and therapeutic value on the product. Free-radical scavenging and acrylamide reduction activities were intermediate and the conferred thermo-halo-stability could be exploited for sustainable clinical and food industry applications.

Interspecific protoplast fusion of atmospheric and room-temperature plasma mutants of Aspergillus generates an L-asparaginase hyper-producing hybrid with techno-economic benefits

The axenic culture of Aspergillus candidus (Asp-C) produced an anti-leukemic L-asparaginase while Aspergillus sydowii (Asp-S) produced the acrylamide-reduction type. Upon mutagenesis by atmospheric and room-temperature plasma (ARTP), their individual L-asparaginase activities improved 2.3-folds in each of Ile^-Thr^-Asp-C-180-K and Val^-Asp-S-180-E stable mutants. Protoplast fusion of selected stable mutants generated fusant-09 with improved anti-leukemic activity, acrylamide reduction, higher temperature optimum and superior kinetic parameters. Submerged (SmF) and solid-state fermentation (SSF) types were compared; likewise batch, fed-batch and continuous fermentation modes; and fed-batch submerged fermentation was selected on the basis of impressive techno-economics. Fusant L-asparaginase was purified by PEG/Na⁺ citrate aqueous two-phase system and molecular exclusion chromatography to 69.96 and 146.21-fold, respectively, and characterized by molecular weight, specificity, activity and stability to chemical and physical agents. Michaelis-Menten kinetics, evaluated under optimum conditions gave K_m, V_max, K_cat, and K_cat/K_m as 1.667 × 10^-3 M, 1666.67 µmol min^-1 mg^-1 protein, 645.99 s^-1 and 3.88 × 10⁵ M^-1 s^-1 respectively. In-vitro cytotoxicity of HL-60 cell lines by fusant-09 L-asparaginase improved 3.00 and 18.71-folds from mutants Ile^-Thr^-Asp-C-180-K and Val^-Asp-S-180-E, and from 5.73 and 32.55 from respective original strains. Free-radical scavenging and acrylamide reduction improvements were intermediate. Fusant-09 L-asparaginase is strongly recommended for sustainable economic anti-leukemic and food industry applications.

Molecular Characterization of a Stable and Robust L-Asparaginase from Pseudomonas sp. PCH199: Evaluation of Cytotoxicity and Acrylamide Mitigation Potential

L-asparaginase is an important industrial enzyme widely used to treat acute lymphoblastic leukemia (ALL) and to reduce acrylamide formation in food products. In the current study, a stable and robust L-asparaginase from Pseudomonas sp. PCH199, with a high affinity for L-asparagine, was cloned and expressed in Escherichia coli BL21(DE3). Recombinant L-asparaginase (Pg-ASNase II) was purified with a monomer size of 37.0 kDa and a native size of 148.0 kDa. During characterization, Pg-ASNase II exhibited 75.8 ± 3.84 U/mg specific activities in 50.0 mM Tris-HCl buffer (pH 8.5) at 50 °C. However, it retained 80 and 70% enzyme activity at 37 °C and 50 °C after 60 min, respectively. The half-life and kd values were 625.15 min and 1.10 × 10−3 min−1 at 37 °C. The kinetic constant Km, Vmax, kcat, and kcat/Km values were 0.57 mM, 71.42 U/mg, 43.34 s−1, and 77.90 ± 9.81 s−1 mM−1 for L-asparagine, respectively. In addition, the enzyme has shown stability in the presence of most metal ions and protein-modifying agents. Pg-ASNase II was cytotoxic towards the MCF-7 cell line (breast cancer) with an estimated IC50 value of 0.169 U/mL in 24 h. Further, Pg-ASNase II treatment led to a 70% acrylamide reduction in baked foods. These findings suggest the potential of Pg-ASNase II in therapeutics and the food industry.

Biochemical characterization and detection of antitumor activity of l-asparaginase from thermophilic Geobacillus kaustophilus DSM 7263T

L-asparaginases, which are oncolytic enzymes, have been used in clinical applications for many years. These enzymes are also important in food processing industry due to their potential in acrylamide-mitigation. In this study, the gene for l-asparaginase (GkASN) from a thermophilic bacterium, Geobacillus kaustophilus, was cloned and expressed in E. coli Rosetta™2 (DE3) cells utilizing the pET-22b(+) vector. The 6xHis-tag attached enzyme was purified and analyzed both biochemically and structurally. The molecular mass of GkASN was determined as ∼36 kDa by SDS-PAGE, Western Blotting, and MALDI-TOF MS analyses. Optimum temperature and pH for the enzyme was determined as 55 °C and 8.5, respectively. The enzyme retained 89% of its thermal stability at 37 °C and 75% at 55 °C after 6 h of incubation. The enzyme activity was inhibited in the presence of Cu²⁺, Fe³⁺, Zn²⁺, and EDTA, while the activity was enhanced in the presence of Mn²⁺, Mg²⁺, and thiol group protective agents such as 2-mercaptoethanol and DTT. The structural modeling analysis demonstrated that the catalytic residues of the enzyme were partially similar to other asparaginases. The therapeutic potential of GkASN was tested on hepatocellular carcinoma cells, a solid cancer type with high mortality rate and rapidly increasing incidence in recent years. We showed that the GkASN-induced asparagine deficiency effectively reduced the metastatic synergy in HCC SNU387 cells on a xCELLigence system with differentiated epithelial Hep3B and poorly differentiated metastatic mesenchymal HCC SNU387 cells.

Molecular cloning, characterization, and in-silico analysis of l-asparaginase from Himalayan Pseudomonas sp. PCH44

l-Asparaginase (l-ASNase) is a key enzyme used to treat acute lymphoblastic leukemia, a childhood blood cancer. Here, we report on the characterization of a recombinant l-ASNase (Ps44-asn II) from Pseudomonas sp. PCH44. The gene was identified from its genome, cloned, and overexpressed in the host Escherichia coli (E. coli). The recombinant l-ASNase (Ps44-ASNase II) was purified with a monomer size of 37.0 kDa and a homotetrameric size of 148.0 kDa. The purified Ps44-ASNase II exhibited optimum activity of 40.84 U/mg in Tris-HCl buffer (50 mM, pH 8.5) at 45 °C for 15 min. It retained 76.53% of enzyme activity at 45 °C after 120 min of incubation. The half-life and K _d values were 600 min and 1.10 × 10^-3 min^-1, respectively, at 45 °C. The kinetic constants values K _m and V _max were 0.56, 0.728 mM, and 29.41, 50.12 U/mg for l-asparagine and l-glutamine, respectively. However, k _cat for l-glutamine is more (30.91 s^-1) than l-asparagine (18.06 s^-1), suggesting that enzymes act more efficiently on l-glutamine than l-asparagine. The docking analysis of l-asparagine and l-glutamine with active site residues of the enzyme revealed a molecular basis for high l-glutaminase (L-GLNase) activity and provided insights into the role of key amino acid residues in the preferential enzymatic activities.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03224-0.

Plant asparaginase versus microbial asparaginase as anticancer agent

The considerable effect of enzymes on human health draws great attention to enzyme-based drugs (therapeutic enzymes), in recent times. L-asparaginase (ASNase) is a well-known therapeutic enzyme. It has varied applications and is a single molecule for the treatment of multiple diseases. This study tries to extract asparaginase from soybean debris (agricultural wastes) as a cheap plant source and compare this with microbial asparaginase as an agent in cancer chemotherapy. The asparaginase was extracted and purified from soybean debris (plant asparaginase) and Pseudomonas aeruginosa (microbial asparaginase), then the physiochemical characters were determined for the two enzymes, and the anticancer activity of plant and microbial asparaginase was determined against gastric cancer (CLS-145), pancreatic cancer (AsPC-1), colon cancer (HCT116), esophagus cancer (KYSE-410), liver cancer (HepG2), breast cancer (MCF-7), and cervical cancer (HELLA). The results showed that plant asparaginase was superior to microbial asparaginase in its physiochemical characters. Plant asparaginase showed higher stability and activity under the conditions of changing either the temperature or the pH; also plant asparaginase has a higher affinity to the asparagine than the microbial asparaginase; besides, this plant asparaginase did not show activity with glutamine as a substrate. The plant asparaginase showed higher anticancer activity than that of microbial asparaginase against all studied cancer cell lines. The present study introduces as the first time a comparative study between the plant and microbial asparaginase which proves that soybean debris asparaginase can be more efficient and safe than that of the microbial asparaginase as an anticancer agent.

Molecular Analysis of L-Asparaginases for Clarification of the Mechanism of Action and Optimization of Pharmacological Functions

L-asparaginases (EC 3.5.1.1) are a family of enzymes that catalyze the hydrolysis of L-asparagine to L-aspartic acid and ammonia. These proteins with different biochemical, physicochemical and pharmacological properties are found in many organisms, including bacteria, fungi, algae, plants and mammals. To date, asparaginases from E. coli and Dickeya dadantii (formerly known as Erwinia chrysanthemi) are widely used in hematology for the treatment of lymphoblastic leukemias. However, their medical use is limited by side effects associated with the ability of these enzymes to hydrolyze L-glutamine, as well as the development of immune reactions. To solve these issues, gene-editing methods to introduce amino-acid substitutions of the enzyme are implemented. In this review, we focused on molecular analysis of the mechanism of enzyme action and to optimize the antitumor activity.

Fusarium sp. L-asparaginases: purification, characterization, and potential assessment as an antileukemic chemotherapeutic agent

Asparaginases important role in the treatment of leukemia. It is part of chemotherapy in the treatment of leukemia in the last three decades. L-Asparaginase is isolated from Fusarium sp. isolated from soil and purified using ammonium sulfate precipitation and Sephadex G 100. Characterization of the crude enzyme revealed it is a metalloprotease inhibited by EDTA. Hg²⁺, Cd²⁺, and Pb²⁺ also inhibited the enzyme. Mg²⁺, Zn²⁺, and Ca²⁺ activated L-asparaginase. Furthermore, kinetic studies of purified enzyme were carried out. V_max and K_m were 0.031 M and 454 U/mL, respectively. The optimum temperature was 30 °C and the optimum pH was 7. Concerning substrate specificity, gelatin and casein in addition to L-asparagine were tested. The enzyme was found to be nonspecific that could hydrolyze all tested substrates at different rates. The maximum enzyme activity was recorded in the case of L-asparagine, followed by casein and gelatin, respectively. The molecular weight of L-asparaginase was 22.5 kDa. The antileukemic cytotoxicity assay of the enzyme against RAW2674 leukemic cell lines by MTT viability test was estimated. The enzyme exhibited antileukemic activity with IC₅₀ of 50.1 UmL^-1. The current work presents additional information regarding the purification and characterization of the enzyme produced by Fusarium sp. and its evaluation as a potential antileukemic chemotherapeutic agent.

Characterization of a Novel L-Asparaginase from Mycobacterium gordonae with Acrylamide Mitigation Potential

L-asparaginase (E.C.3.5.1.1) is a well-known agent that prevents the formation of acrylamide both in the food industry and against childhood acute lymphoblastic leukemia in clinical settings. The disadvantages of L-asparaginase, which restrict its industrial application, include its narrow range of pH stability and low thermostability. In this study, a novel L-asparaginase from Mycobacterium gordonae (GmASNase) was cloned and expressed in Escherichia coli BL21 (DE3). GmASNase was found to be a tetramer with a monomeric size of 32 kDa, sharing only 32% structural identity with Helicobacter pylori L-asparaginases in the Protein Data Bank database. The purified GmASNase had the highest specific activity of 486.65 IU mg⁻¹ at pH 9.0 and 50 °C. In addition, GmASNase possessed superior properties in terms of stability at a wide pH range of 5.0–11.0 and activity at temperatures below 40 °C. Moreover, GmASNase displayed high substrate specificity towards L-asparagine with Km, kcat, and kcat/Km values of 6.025 mM, 11,864.71 min⁻¹ and 1969.25 mM⁻¹min⁻¹, respectively. To evaluate its ability to mitigate acrylamide, GmASNase was used to treat potato chips prior to frying, where the acrylamide content decreased by 65.09% compared with the untreated control. These results suggest that GmASNase is a potential candidate for applications in the food industry.

Superior operational stability of immobilized L-asparaginase over surface-modified carbon nanotubes

L-asparaginase (ASNase, EC 3.5.1.1) is an enzyme that catalyzes the L-asparagine hydrolysis into L-aspartic acid and ammonia, being mainly applied in pharmaceutical and food industries. However, some disadvantages are associated with its free form, such as the ASNase short half-life, which may be overcome by enzyme immobilization. In this work, the immobilization of ASNase by adsorption over pristine and modified multi-walled carbon nanotubes (MWCNTs) was investigated, the latter corresponding to functionalized MWCNTs through a hydrothermal oxidation treatment. Different operating conditions, including pH, contact time and ASNase/MWCNT mass ratio, as well as the operational stability of the immobilized ASNase, were evaluated. For comparison purposes, data regarding the ASNase immobilization with pristine MWCNT was detailed. The characterization of the ASNase-MWCNT bioconjugate was addressed using different techniques, namely Transmission Electron Microscopy (TEM), Thermogravimetric Analysis (TGA) and Raman spectroscopy. Functionalized MWCNTs showed promising results, with an immobilization yield and a relative recovered activity of commercial ASNase above 95% under the optimized adsorption conditions (pH 8, 60 min of contact and 1.5 × 10-3 g mL-1 of ASNase). The ASNase-MWCNT bioconjugate also showed improved enzyme operational stability (6 consecutive reaction cycles without activity loss), paving the way for its use in industrial processes.

Microbial L-asparaginase for Application in Acrylamide Mitigation from Food: Current Research Status and Future Perspectives

L-asparaginase (E.C.3.5.1.1) hydrolyzes L-asparagine to L-aspartic acid and ammonia, which has been widely applied in the pharmaceutical and food industries. Microbes have advantages for L-asparaginase production, and there are several commercially available forms of L-asparaginase, all of which are derived from microbes. Generally, L-asparaginase has an optimum pH range of 5.0-9.0 and an optimum temperature of between 30 and 60 °C. However, the optimum temperature of L-asparaginase from hyperthermophilic archaea is considerable higher (between 85 and 100 °C). The native properties of the enzymes can be enhanced by using immobilization techniques. The stability and recyclability of immobilized enzymes makes them more suitable for food applications. This current work describes the classification, catalytic mechanism, production, purification, and immobilization of microbial L-asparaginase, focusing on its application as an effective reducer of acrylamide in fried potato products, bakery products, and coffee. This highlights the prospects of cost-effective L-asparaginase, thermostable L-asparaginase, and immobilized L-asparaginase as good candidates for food application in the future.

Tailor-made shape memory stents for therapeutic enzymes: A novel approach to enhance enzyme performance

Herein, our suggestion is to immobilize enzymes in-situ on absorbable shape-memory stents instead of injecting therapeutic enzymes into the blood. Chitosan (CHI)-based stents were tailored as novel support and the enzyme-immobilizing ability was elucidated using L-asparaginase (L-ASNase). For developing shape-memory stents, CHI-glycerol (GLY) solution was prepared and further blended with different ratios of polyethylene glycol (PEG), and polyvinyl alcohol (PVA). Afterward, the blends were modified by ionic crosslinking with sodium tripolyphosphate to obtain a shape-memory character. L-ASNase was included in the blends by using in-situ method before ionic crosslinking. The prepared stents, with or without L-ASNase, were comprehensively characterized by using several techniques. Collectively, immobilized L-ASNase exhibited much better performance in immobilization parameters than free one, thanks to its improved stability and reusability. For instance, CHI/GLY/PEG-3@L-ASNase retained about 70% of the initial activity after storage at 30 °C for 2 weeks, whereas the free form lost half of its initial activity. Besides, it retained 73.4% residual activity after 15 consecutive cycles. Most importantly, stent formulations exhibited ~60% activity in the bioreactor system after 4 weeks of incubation. Given the above results, shape-memory stents can be a promising candidate as a new platform for immobilization, especially in the blood circulation system.

L-asparaginase production review: bioprocess design and biochemical characteristics

In the past decades, the production of biopharmaceuticals has gained high interest due to its great sensitivity, specificity, and lower risk of negative effects to patients. Biopharmaceuticals are mostly therapeutic recombinant proteins produced through biotechnological processes. In this context, L-asparaginase (L-asparagine amidohydrolase, L-ASNase (E.C. 3.5.1.1)) is a therapeutic enzyme that has been abundantly studied by researchers due to its antineoplastic properties. As a biopharmaceutical, L-ASNase has been used in the treatment of acute lymphoblastic leukemia (ALL), acute myeloblastic leukemia (AML), and other lymphoid malignancies, in combination with other drugs. Besides its application as a biopharmaceutical, this enzyme is widely used in food processing industries as an acrylamide mitigation agent and as a biosensor for the detection of L-asparagine in physiological fluids at nano-levels. The great demand for L-ASNase is supplied by recombinant enzymes from Escherichia coli and Erwinia chrysanthemi. However, production processes are associated to low yields and proteins associated to immunogenicity problems, which leads to the search for a better enzyme source. Considering the L-ASNase pharmacological and food importance, this review provides an overview of the current biotechnological developments in L-ASNase production and biochemical characterization aiming to improve the knowledge about its production. KEY POINTS: • Microbial enzyme applications as biopharmaceutical and in food industry • Biosynthesis process: from the microorganism to bioreactor technology • Enzyme activity and kinetic properties: crucial for the final application.

Bioprocess development for enhanced endoglucanase production by newly isolated bacteria, purification, characterization and in-vitro efficacy as anti-biofilm of Pseudomonas aeruginosa

Endoglucanase producing bacteria were isolated from Egyptian soils and the most active bacterial strain was identified as Bacillus subtilis strain Fatma/1. Plackett-Burman statistical design was carried out to assess the effect of seven process variables on endoglucanase production. Carboxymethyl cellulose (CMC), yeast extract and peptone were the most significant variables that enhanced the endoglucanase production and thus were selected for further optimization using face-centered central composite design. The highest yield of endoglucanase (32.37 U/mL) was obtained in run no. 9, using 18 g/L CMC, 8 g/L peptone, 7 g/L yeast extract and 0.1 g/L FeSO₄.7H₂O. The optimized medium showed about eightfold increase in endoglucanase production compared to the unoptimized medium. The produced crude enzyme was further purified by ammonium sulfate precipitation, then DEAE-Sepharose CL6B column. The purified enzyme was shown to have a molecular weight of 37 kDa. The enzyme showed maximum activity at pH 8.0, temperature of 50 °C, incubation time of 60 min. The half-life time (T_1/2) was 139.53 min at 50 °C, while being 82.67 min at 60 °C. Endoglucanase at concentration of 12 U/mL effectively removed 84.61% of biofilm matrix of Pseudomonas aeruginosa with marked reduction in carbohydrate content of the biofilm from 63.4 to 7.9 μg.

Molecular Attributes Associated With Refolding of Inclusion Body Proteins Using the Freeze-Thaw Method

Understanding the structure-function of inclusion bodies (IBs) in the last two decades has led to the development of several mild solubilization buffers for the improved recovery of bioactive proteins. The recently developed freeze-thaw-based inclusion body protein solubilization method has received a great deal of attention due to its simplicity and cost-effectiveness. The present report investigates the reproducibility, efficiency, and plausible mechanism of the freeze-thaw-based IB solubilization. The percentage recovery of functionally active protein species of human growth hormone (hGH) and L-asparaginase from their IBs in Escherichia coli and the quality attributes associated with the freeze-thaw-based solubilization method were analyzed in detail. The overall yield of the purified hGH and L-asparaginase protein was found to be around 14 and 25%, respectively. Both purified proteins had functionally active species lower than that observed with commercial proteins. Biophysical and biochemical analyses revealed that the formation of soluble aggregates was a major limitation in the case of tough IB protein like hGH. On the other hand, the destabilization of soft IB protein like L-asparaginase led to the poor recovery of functionally active protein species. Our study provides insight into the advantages, disadvantages, and molecular-structural information associated with the freeze-thaw-based solubilization method.

Bioprocess Optimization of Nutritional Parameters for Enhanced Anti-leukemic L-Asparaginase Production by Aspergillus candidus UCCM 00117: A Sequential Statistical Approach

Sequential optimization of bioprocess nutritional conditions for production of glutaminase-near-free L-asparaginase by Aspergillus candidus UCCM 00117 was conducted under shake flask laboratory conditions. Catalytic and anti-cancer activities of the poly-peptide were evaluated using standard in vitro biochemical methods. Medium nutrients were selected by one-factor-at-a-time (OFAT) approach while Plackett-Burman design (PBD) screened potential factors for optimization. Path of steepest ascent (PSA) and response surface methodology (RSM) of a Min-Run-Res V fractional factorial of a central composite rotatable design (CCRD) were employed to optimize factor levels towards improved enzyme activity. A multi-objective approach using desirability function generated through predictor importance and weighted coefficient methodology was adopted for optimization. The approach set optimum bioprocess conditions as 49.55 g/L molasses, 64.98% corn steep liquor, 44.23 g/L asparagine, 1.73 g/L potassium, 0.055 g/L manganese and 0.043 g/L chromium (III) ions, at a composite desirability of 0.943 and an L-asparaginase activity of 5216.95U. The Sephadex-200 partially-purified polypeptide had a specific activity of 476.84 U/mg; 0.087U glutaminase activity, 36.46% yield and 20-fold protein purification. Anti-cancer activity potentials of the catalytic poly-peptide were dose-dependent with IC₅₀ (µg/mL): 4.063 (HL-60), 13.75 (HCT-116), 15.83 (HeLa), 11.68 (MCF-7), 7.61 (HepG-2). The therapeutic enzyme exhibited 15-fold more cytotoxicity to myeloid leukemia cell line than to normal (HEK 238 T) cell. Optimum temperature and pH for activity were within physiological range. However, significant interactions between exposure time and levels of each of temperature and pH made interpretations of residual enzyme activities difficult. The manganese-dependent L-asparaginase from Aspergillu s candidus UCCM 00117 is recommended for further anticancer drug investigations.

Yarrowia lipolytica L-asparaginase inhibits the growth and migration of lung (A549) and breast (MCF7) cancer cells

L-asparaginase is an enzyme capable of hydrolyzing the asparagine to aspartic acid and ammonia. L-asparaginase is widely used in the treatment of acute lymphoblastic leukemia (ALL) and other cancers. Here, for the first time, the effects of a novel yeast L-asparaginase from Yarrowia lipolytica were studied on human lung (A549) and breast cancer (MCF7) cell lines as the solid cancer cell lines in terms of cell growth and metastasis inhibition. Functional analysis showed the L-asparagine deprivation mediated anti-proliferation effects by apoptosis induction and changes in the expression of target genes involved in apoptosis and migration pathways. The qRT-PCR analysis showed the higher expression levels of pro-apoptosis genes, including Bax, P53, caspase 3, caspase 8, and down-regulation of Bcl-2 anti-apoptotic gene in treated cells. On the other hand, there was no increase in ROS production in the treated cells. However, L-asparaginase treatment was able to significantly induce autophagy activation in A549 cells. Besides, wound healing assay showed that L-asparaginase could considerably inhibit the migration of A549 and MCF7 cells. Taken together, our results suggested that Yarrowia lipolytica L-asparaginase might be considered for enzyme therapy against breast and lung cancers.

Identification of L-asparaginases from Streptomyces strains with competitive activity and immunogenic profiles: a bioinformatic approach

The enzyme L-asparaginase from Escherichia coli is a therapeutic enzyme that has been a cornerstone in the clinical treatment of acute lymphoblastic leukemia for the last decades. However, treatment effectiveness is limited by the highly immunogenic nature of the protein and its cross-reactivity towards L-glutamine. In this work, a bioinformatic approach was used to identify, select and computationally characterize L-asparaginases from Streptomyces through sequence-based screening analyses, immunoinformatics, homology modeling, and molecular docking studies. Based on its predicted low immunogenicity and excellent enzymatic activity, we selected a previously uncharacterized L-asparaginase from Streptomyces scabrisporus. Furthermore, two putative asparaginase binding sites were identified and a 3D model is proposed. These promising features allow us to propose L-asparaginase from S. scabrisporus as an alternative for the treatment of acute lymphocytic leukemia.

A comprehensive review on microbial l-asparaginase: Bioprocessing, characterization, and industrial applications

l-Asparaginase (E.C.3.5.1.1.) is a vital enzyme that hydrolyzes l-asparagine to l-aspartic acid and ammonia. This property of l-asparaginase inhibits the protein synthesis in cancer cells, making l-asparaginase a mainstay of pediatric chemotherapy practices to treat acute lymphoblastic leukemia (ALL) patients. l-Asparaginase is also recognized as one of the important food processing agent. The removal of asparagine by l-asparaginase leads to the reduction of acrylamide formation in fried food items. l-Asparaginase is produced by various organisms including animals, plants, and microorganisms, however, only microorganisms that produce a substantial amount of this enzyme are of commercial significance. The commercial l-asparaginase for healthcare applications is chiefly derived from Escherichia coli and Erwinia chrysanthemi. A high rate of hypersensitivity and adverse reactions limits the long-term clinical use of l-asparaginase. Present review provides thorough information on microbial l-asparaginase bioprocess optimization including submerged fermentation and solid-state fermentation for l-asparaginase production, downstream purification, its characterization, and issues related to the clinical application including toxicity and hypersensitivity. Here, we have highlighted the bioprocess techniques that can produce improved and economically viable yields of l-asparaginase from promising microbial sources in the current scenario where there is an urgent need for alternate l-asparaginase with less adverse effects.

Comparative study of ASNase immobilization on tannic acid-modified magnetic Fe3O4/SBA-15 nanoparticles to enhance stability and reusability

Herein, we report the preparation of tannic acid-modified magnetic Fe₃O₄/SBA-15 nanoparticles and their application as a carrier matrix for immobilization of ASNase, an anticancer enzyme-drug.

Process development for scale-up production of a therapeutic L-asparaginase by Streptomyces brollosae NEAE-115 from shake flasks to bioreactor

L-asparaginase is a promising enzyme that has a wide range of significant applications including cancer therapy and starchy food industries. The statistical design of Plackett-Burman and face centered central composite design were employed to optimize L-asparaginase production by Streptomyces brollosae NEAE-115. As a result, a medium of the following formula is the optimum for producing L-asparaginase in the culture filtrate of Streptomyces brollosae NEAE-115: Dextrose 2 g, starch 20 g, L-asparagine 10 g, KNO3 1 g, K2HPO4 1 g, MgSO4.7H2O 0.5 g, NaCl 0.1 g, pH 7, fermentation period 7 days, temperature 30 °C, inoculum size 4%, v/v, agitation speed 150 rpm and inoculum age 48 h. The kinetics of cell growth, carbohydrates consumption and L- asparaginase production were studied in 7-L stirred tank bioreactor under different cultivation conditions. A significant increase in both cell growth and carbohydrate consumption was observed as the stirring speed increased from 200 to 600 rpm under uncontrolled pH. The highest L- asparaginase activity of 108.46 U/mL was obtained after 96 h at 400 rpm. On the other hand, the specific enzyme production (Yp/x) under uncontrolled pH reached its maximal value of about 20.3 U/mg cells. Further improvement of enzyme production was attained by controlling pH at 7 using the selected stirring speed of 400 rpm. Enzyme production of 162.11 U/mL obtained from the controlled pH cultures exceeded this value gained from uncontrolled pH (108.46 U/mL) by about 50%.

Recombinant l-Asparaginase II from Lactobacillus casei subsp. casei ATCC 393 and Its Anticancer Activity

l-asparaginases from bacterial origin are employed extensively in leukemic treatment and food industry. The present study focuses on the characterization of the recombinant l-asparaginase II from Lactobacillus casei subsp. casei ATCC 393 cloned into Escherichia coli expression system and purified using Ni-NTA chromatography. The recombinant l-asparaginase as a monomer had a molecular weight of 35 kDa. The enzyme was active from 10 to 80 °C with the optimum at 40 °C. The enzyme retained its activity at 28 °C and 37 °C up to 24 h. The enzyme had optimum pH of 6 and retained 50% activity till 18 h. The K_m of the recombinant enzyme was 0.01235 mM and V_max 1.576 mM/min. The half life of recombinant l-asparaginase II in human serum was 44 h and trypsin was for 15 min. The LC-MS/MS analysis revealed the molecular weight of 35,050 and pI of 5.64. The secondary structure prediction using CD spectroscopy for the recombinant enzyme showed 33.5% α-helix, 66.5% turn and 0% β sheets. The cytotoxicity of the recombinant enzyme was analysed against MOLT 3, Jurkat E6.1 and K-562 with the IC 50 value of 30, 62.5 and 50 µg/ml.

Production and Anticancer Activity of an L-Asparaginase from Bacillus licheniformis Isolated from the Red Sea, Saudi Arabia

Microbial L-asparaginase (ASNase) is an important anticancer agent that is used extensively worldwide. In this study, 40 bacterial isolates were obtained from the Red Sea of Saudi Arabia and screened for ASNase production using a qualitative rapid plate assay, 28 of which were producing large L-asparagine hydrolysis zones. The ASNase production of the immobilized bacterial cells was more favorable than that of freely suspended cells. A promising isolate, KKU-KH14, was identified by 16S rRNA gene sequencing as Bacillus licheniformis. Maximal ASNase production was achieved using an incubation period of 72 h, with an optimum of pH 6.5, an incubation temperature of 37 °C, an agitation rate 250 rpm, and with glucose and (NH4)2SO4 used as the carbon and nitrogen sources, respectively. The glutaminase activity was not detected in the ASNase preparations. The purified ASNase showed a final specific activity of 36.08 U/mg, and the molecular weight was found to be 37 kDa by SDS-PAGE analysis. The maximum activity and stability of the purified enzyme occurred at pH values of 7.5 and 8.5, respectively, with maximum activity at 37 °C and complete thermal stability at 70 °C for 1 h. The Km and Vmax values of the purified enzyme were 0.049995 M and of 45.45 μmol/ml/min, respectively. The anticancer activity of the purified ASNase showed significant toxic activity toward HepG-2 cells (IC50 11.66 µg/mL), which was greater than that observed against MCF-7 (IC50 14.55 µg/mL) and HCT-116 cells (IC50 17.02 µg/mL). The results demonstrated that the Red Sea is a promising biological reservoir, as shown by the isolation of B. licheniformis, which produces a glutaminase free ASNase and may be a potential candidate for further pharmaceutical use as an anticancer drug.