L-asparaginase – A promising biocatalyst for industrial and clinical applications

Identification and Thermostability Modification of the Mesophilic L-asparaginase from Limosilactobacillus secaliphilus

L-asparaginase (L-ASNase, E.C.3.5.1.1) could effectively inhibit the formation of acrylamide (AA) by hydrolyzing the AA precursor L-asparagine. However, most of the L-ASNases showed a relatively weak thermostability, posing a big threat on the application of enzyme at high processing temperatures. Here, the recombinant L-ASNase from mesophilic bacteria Limosilactobacillus secaliphilus was identified for the first time. The recombinant enzyme exhibited its optimal activity at pH 8.0 and 60 ℃. Additionally, the thermostability of L. secaliphilus L-ASNase was enhanced by site-directed mutagenesis after multiple sequence alignment. Ten mutants were reasonably constructed, among which the single-point mutants L24Y, S55T, and V155S showed more than 1 ℃ elevated Tm value compared to the wild-type enzyme. In addition, the half-life of mutant at 40, 50, and 55 ℃ was 376.7 min, 62.1 min, and 18.7 min, much higher than that of wild-type enzyme. The molecular dynamic simulation showed that compared to the wild-type enzyme, the structural stability of V155S was greatly strengthened due to the lower RMSF and RMSD value as well as a decreased total energy compared to that of the wild-type enzyme. The results were positive and provided some useful information for the thermostability modification of L-ASNase.

Improved L-Asparaginase Properties and Reusability by Immobilization onto Functionalized Carbon Xerogels

Enzyme immobilization can offer a range of significant advantages, including reusability, and increased selectivity, stability, and activity. In this work, a central composite design (CCD) of experiments and response surface methodology (RSM) were used to study, for the first time, the L-asparaginase (ASNase) immobilization onto functionalized carbon xerogels (CXs). The best results were achieved using CXs obtained by hydrothermal oxidation with nitric acid and subsequent heat treatment in a nitrogen flow at 600 °C (CX-OX-600). Under the optimal conditions (81 min of contact time, pH 6.2 and 0.36 g/L of ASNase), an immobilization yield (IY) of 100 % and relative recovered activity (RRA) of 103 % were achieved. The kinetic parameters obtained also indicate a 1.25-fold increase in the affinity of ASNase towards the substrate after immobilization. Moreover, the immobilized enzyme retained 97 % of its initial activity after 6 consecutive reaction cycles. All these outcomes confirm the promising properties of functionalized CXs as support for ASNase, bringing new insights into the development of an efficient and stable immobilization platform for use in the pharmaceutical industry, food industry, and biosensors.

Cloning, expression, and characterization of a novel thermo-acidophilic l-asparaginase of Pseudomonas aeruginosa CSPS4

In the present investigation, a soil isolate Pseudomonas aeruginosa CSPS4 was used for retrieving the l-asparaginase encoding gene (Asn_PA) of size 1089 bp. The gene was successfully cloned into the pET28a (+) vector and expressed into E. coli BL21(DE3) for characterization of the protein. The recombinant rAsn_PA enzyme was purified by affinity chromatography using Ni-NTA2+ resins. Molecular weight analysis using SDS-PAGE unveiled rAsn_PA as a monomeric protein of molecular weight ~ 35 kDa. On characterization, the recombinant rAsn_PA showed optimum pH and temperature of 6.0 and 60 °C, respectively, along with significant stability at 50-70 °C, along with 50% residual activity at 80 °C after 3 h of incubation. Similarly, the rAsn_PA exhibited asparaginase activity over a broad pH range between 4 and 8. The enzyme was not significantly inhibited in the presence of detergents. The rAsn_PA was grouped into the asparaginase-glutaminase family II due to the glutaminase activity. The purified rAsn_PA showed antitumor activity by exhibiting a cytotoxic effect on three different cell lines, where IC50 of purified rAsn_PA was 2.3 IU, 3.7 IU, and 20.5 IU for HL-60, MOLM-13, and K-562 cell lines, respectively. Thus, recombinant rAsn_PA of P. aeruginosa CSPS4 may also be explored as an antitumor agent after reducing or minimizing the glutaminase activity. Thermo-acidophilic properties of rAsn_PA make it a novel enzyme that needs to be further investigated.

Characterization of a Type II L-Asparaginase from the Halotolerant Bacillus subtilis CH11

L-asparaginases from bacterial sources have been used in antineoplastic treatments and the food industry. A type II L-asparaginase encoded by the N-truncated gene ansZP21 of halotolerant Bacillus subtilis CH11 isolated from Chilca salterns in Peru was expressed using a heterologous system in Escherichia coli BL21 (DE3)pLysS. The recombinant protein was purified using one-step nickel affinity chromatography and exhibited an activity of 234.38 U mg-1 and a maximum catalytic activity at pH 9.0 and 60 °C. The enzyme showed a homotetrameric form with an estimated molecular weight of 155 kDa through gel filtration chromatography. The enzyme half-life at 60 °C was 3 h 48 min, and L-asparaginase retained 50% of its initial activity for 24 h at 37 °C. The activity was considerably enhanced by KCl, CaCl2, MgCl2, mercaptoethanol, and DL-dithiothreitol (p-value < 0.01). Moreover, the Vmax and Km were 145.2 µmol mL-1 min-1 and 4.75 mM, respectively. These findings evidence a promising novel type II L-asparaginase for future industrial applications.

Current state of molecular and metabolic strategies for the improvement of L-asparaginase expression in heterologous systems

Heterologous expression of L-asparaginase (L-ASNase) has become an important area of research due to its clinical and food industry applications. This review provides a comprehensive overview of the molecular and metabolic strategies that can be used to optimize the expression of L-ASNase in heterologous systems. This article describes various approaches that have been employed to increase enzyme production, including the use of molecular tools, strain engineering, and in silico optimization. The review article highlights the critical role that rational design plays in achieving successful heterologous expression and underscores the challenges of large-scale production of L-ASNase, such as inadequate protein folding and the metabolic burden on host cells. Improved gene expression is shown to be achievable through the optimization of codon usage, synthetic promoters, transcription and translation regulation, and host strain improvement, among others. Additionally, this review provides a deep understanding of the enzymatic properties of L-ASNase and how this knowledge has been employed to enhance its properties and production. Finally, future trends in L-ASNase production, including the integration of CRISPR and machine learning tools are discussed. This work serves as a valuable resource for researchers looking to design effective heterologous expression systems for L-ASNase production as well as for enzymes production in general.

l-Asparaginase producing novel Streptomyces sp. HB2AG: optimization of process parameters and whole genome sequence analysis

l-asparaginase (ASNase) is a key enzyme widely used as an anti-cancer drug and is also used in the pharmaceutical and food processing industries. This enzyme's applications are determined by its source and nature. The production of the enzyme through the fermentation process is also crucial for economic feasibility. Searching for a new potent microbial strain is necessary for increased ASNase synthesis. In this work, a potent strain was isolated from the sediment of Chilika Lake and selected for its high ASNase production potential. It was recognized following Bergey's manual of determinative and phylogenetic analysis was carried out by 16S rDNA sequencing. The isolated organism was Streptomyces sp. HB2AG. Additionally, a genome-wide analysis of HB2AG was performed. The result showed that the HB2AG genome possesses a chromosome with 6,099,956 bp and GC content of 74.0%. The whole genome analysis of the strain HB2AG revealed the presence of ASNase (ansA, ansB) and Asparagine synthase (asnB) in the HB2AG genome. Optimization of media composition is crucial for microbial growth and obtaining the desired end product. The current effort focuses on the Taguchi orthogonal design to determine optimum factor combinations that would allow the strain to produce maximum ASNase enzyme. Results showed that compared to unoptimized media, approximately 1.76-fold higher ASNase production was observed in Sea Water Luria Bertani (SWLB) media, pH-5, 0.5% (w/v) of lactose, 0.5% (w/v) of casein, 2.5% (w/v) NaCl, 1 mM Ca2+ and 0.1% Tween 80.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03620-0.

Insights into the Distribution and Functional Properties of l-Asparaginase in the Archaeal Domain and Characterization of Picrophilus torridus Asparaginase Belonging to the Novel Family Asp2like1

l-Asparaginase catalyzes the hydrolysis of l-asparagine to aspartic acid and ammonia and is used in the medical and food industries. In this investigation, from the proteomes of 176 archaeal organisms (with completely sequenced genomes), 116 homologs of l-asparaginase were obtained from 86 archaeal organisms segregated into Asp1, Asp2, IaaA, Asp2like1, and Asp2like2 families based on the conserved domain. The similarities and differences in the structure of selected representatives from each family are discussed. From the two novel archaeal l-asparaginase families Asp2like1 and Asp2like2, a representative of Asp2like1 family Picrophilus torridus asparaginase (PtAsp2like1) was characterized in detail to find its suitability in therapeutics. PtAsp2like1 was a glutaminase-free asparaginase that showed the optimum activity at 80 °C and pH 10.0. The Km of PtAsp2like1 toward substrate l-asparagine was 11.69 mM. This study demonstrates the improved mapping of asparaginases in the archaeal domain, facilitating future focused research on archaeal asparaginases for therapeutic applications.

Extracellular expression of Saccharomyces cerevisiae's L-asparaginase II in Pichia pastoris results in novel enzyme with better parameters

L-asparaginase (ASNase) is an efficient inhibitor of tumor development, used in chemotherapy sessions against acute lymphoblastic leukemia (ALL) tumor cells; its use results in 80% complete remission of the disease in treated patients. Saccharomyces cerevisiae's L-asparaginase II (ScASNaseII) has a high potential to substitute bacteria ASNase in patients that developed hypersensitivity, but the endogenous production of it results in hypermannosylated immunogenic enzyme. Here we describe the genetic process to acquire the ScASNaseII expressed in the extracellular medium. Our strategy involved a fusion of mature sequence of protein codified by ASP3 (amino acids 26-362) with the secretion signal sequence of Pichia pastoris acid phosphatase enzyme; in addition, this DNA construction was integrated in P. pastoris Glycoswitch^® strain genome, which has the cellular machinery to express and secrete high quantity of enzymes with humanized glycosylation. Our data show that the DNA construction and strain employed can express extracellular asparaginase with specific activity of 218.2 IU mg^-1. The resultant enzyme is 40% more stable than commercially available Escherichia coli's ASNase (EcASNaseII) when incubated with human serum. In addition, ScASNaseII presents 50% lower cross-reaction with anti-ASNase antibody produced against EcASNaseII when compared with ASNase from Dickeya chrysanthemi.

Immobilization and Characterization of L-Asparaginase over Carbon Xerogels

L-asparaginase (ASNase) is an aminohydrolase currently used in the pharmaceutical and food industries. Enzyme immobilization is an exciting option for both applications, allowing for a more straightforward recovery and increased stability. High surface area and customizable porosity make carbon xerogels (CXs) promising materials for ASNase immobilization. This work describes the influence of contact time, pH, and ASNase concentration on the immobilization yield (IY) and relative recovered activity (RRA) using the Central Composite Design methodology. The most promising results were obtained using CX with an average pore size of 4 nm (CX-4), reaching IY and RRA of 100%. At the optimal conditions (contact time 49 min, pH 6.73, and [ASNase] 0.26 mg·mL⁻¹), the ASNase-CXs biocomposite was characterized and evaluated in terms of kinetic properties and operational, thermal, and pH stabilities. The immobilized ASNase onto CX-4 retained 71% of its original activity after six continuous reaction cycles, showed good thermal stability at 37 °C (RRA of 91% after 90 min), and was able to adapt to both acidic and alkaline environments. Finally, the results indicated a 3.9-fold increase in the immobilized ASNase affinity for the substrate, confirming the potential of CXs as a support for ASNase and as a cost-effective tool for subsequent use in the therapeutic and food sectors.

Rhizopus oryzae AM16; a new hyperactive L‑asparaginase producer: Semi solid‑state production and anticancer activity of the partially purified protein

The demand for L-asparaginase is predicted to increase several fold in the future due to its potential clinical applications in the treatment of lymphoid system malignancies and leukemia. Thus identifying suitable sources of production should be considered high priority. Fungi are valuable organisms as they are able to convert what would be considered ‘useless’ materials into materials that have potential value. The present study provides a proof of concept of production of a new hyperactive L-asparaginase producer (Rhizopus oryzae AM16), which was successfully isolated and sequentially optimized using a semi solid-state fermentation method with a simple and cheap medium produced from wheat bran (WB). The fungus was able to produce an appreciable amount of the enzyme (2,875.9 U) after 8 days of incubation under 85.7% moisture, in the presence of magnesium nitrate (5.0 mg N/mg nitrogen per gram of dry WB) at pH 5.8. Testing the anticancer activity confirmed the ability of the resultant enzyme to inhibit the growth of various types of cancer cells (HepG2, MCF-7, HCT and A549). The IC₅₀ values of the dialyzed enzyme were lower than that of the crude product. Thus, this newly identified and purified L-asparaginase may be a promising anticancer drug.

Technological Prospecting: Mapping Patents on L-asparaginases from Extremophilic Microorganisms

BACKGROUND

L-asparaginase (L-ASNase, L-asparagine amidohydrolase, E.C.3.5.1.1) is an enzyme with wide therapeutic applicability. Currently, the commercialized L-ASNase comes from mesophilic organisms, presenting low specificity to the substrate and limitations regarding thermostability and active pH range. Such factors prevent the maximum performance of the enzyme in different applications. Therefore, extremophilic organisms may represent important candidates for obtaining amidohydrolases with particular characteristics desired by the biotechnological market.

OBJECTIVES

The present study aims to carry out a technological prospecting of patents related to the L-asparaginases derived from extremophilic organisms, contributing to pave the way for further rational investigation and application of such enzymes.

METHODS

This patent literature review used six patents databases: The LENS, WIPO, EPO, USPTO, Patent Inspiration, and INPI.

RESULTS

It was analyzed 2860 patents, and 14 were selected according to combinations of descriptors and study criteria. Approximately 57.14% of the patents refer to enzymes obtained from archaea, especially from the speciesPyrococcus yayanosii (35.71% of the totality).

CONCLUSION

The present prospective study has singular relevance since there are no recent patent reviews for L-asparaginases, especially produced by extremophilic microorganisms. Although such enzymes have well-defined applications, corroborated by the patents compiled in this review, the most recent studies allude to new uses, such as the treatment of infections. The characterization of the catalytic profiles allows us to infer that there are potential sources still unexplored. Hence, the search for new L-ASNases with different characteristics will continue to grow in the coming years and, possibly, ramifications of the technological routes will be witnessed.

Microbial production, molecular modification, and practical application of l-Asparaginase: A review

L-Asparaginase (L-ASNase, EC 3.5.1.1), an antitumor drug for acute lymphoblastic leukemia (ALL) therapy, is widely used in the clinical field. Similarly, L-ASNase is also a powerful and significant biological tool in the food industry to inhibit acrylamide (AA) formation. This review comprehensively summarizes the latest achievements and improvements in the production, modification, and application of microbial L-ASNase. To date, the expression levels and optimization of expression hosts such as Escherichia coli, Bacillus subtilis, and Pichia pastoris, have made significant progress. In addition, examples of successful modification of L-ASNase such as decreasing glutaminase activity, increasing the in vivo stability, and enhancing thermostability have been presented. Impressively, the application of L-ASNase as a food addition aid, as well as its commercialization in the pharmaceutical field, and cutting-edge biosensor application developments have been summarized. The presented results and proposed ideas could be a good guide for other L-ASNase researchers in both scientific and practical fields.

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.

Pseudomonas aeruginosa recombinant L-asparaginase: Large scale production, purification, and cytotoxicity on THP-1, MDA-MB-231, A549, Caco2 and HCT-116 cell lines

In previous studies Pseudomonas aeruginosal-ASNase complete coding sequence gene, 984 bp (GenBank accession number KU161101.2) was isolated by PCR, cloned into pET28a(+) vector, expressed in E. coli DE3(BL21) pLysS, purified to apparent homogeneity and biochemically characterized. In the present work we highlight large scale production, affinity purification of the recombinant enzyme, effect of osmolytes on the stability of the l-ASNase and cytotoxicity on different cancer cell lines. Successful overexpression was achieved in E. coli as a 6-His-Tag fusion protein after 18 h of induction with lactose at a concentration of 2 g/L in fermentation medium and at 37 °C. The recombinant enzyme was purified to homogeneity using Ni²⁺ chelated Fast Flow Sepharose resin with 19758.8 specific activity and 10.28 purification fold. With respect to the effect of osmolytes on the stability of the purified enzyme, the majority of the tested osmolytes namely 5% maltose, 5% mannitol, 30% glycerol and 5% BSA were found to increase the stability of the recombinant l-ASNase as compared to the free enzyme. Triple negative breast cancer cell line, MDA-MB-231 treated with recombinant l-ASNase showed significant morphological changes and the IC₅₀ of the purified enzyme was found to be 3.1 IU. Human leukemia cell line, THP-1 treated with l-ASNase showed apoptotic bodies and morphological changes with IC₅₀ of the purified enzyme 1.75 IU. Moreover, the purified recombinant l-ASNase was found to induced cytotoxic effects on colorectal adenocarcinoma cell line, Caco-2 with IC₅₀ of 68.28 IU. Results of apoptosis assay on THP-1 cells revealed that the purified l-ASNase induced early and late apoptosis at 14.16% and 7.56 respectively as compared to the control untreated cells.

Recent Strategies and Applications for l-Asparaginase Confinement

l-asparaginase (ASNase, EC 3.5.1.1) is an aminohydrolase enzyme with important uses in the therapeutic/pharmaceutical and food industries. Its main applications are as an anticancer drug, mostly for acute lymphoblastic leukaemia (ALL) treatment, and in acrylamide reduction when starch-rich foods are cooked at temperatures above 100 °C. Its use as a biosensor for asparagine in both industries has also been reported. However, there are certain challenges associated with ASNase applications. Depending on the ASNase source, the major challenges of its pharmaceutical application are the hypersensitivity reactions that it causes in ALL patients and its short half-life and fast plasma clearance in the blood system by native proteases. In addition, ASNase is generally unstable and it is a thermolabile enzyme, which also hinders its application in the food sector. These drawbacks have been overcome by the ASNase confinement in different (nano)materials through distinct techniques, such as physical adsorption, covalent attachment and entrapment. Overall, this review describes the most recent strategies reported for ASNase confinement in numerous (nano)materials, highlighting its improved properties, especially specificity, half-life enhancement and thermal and operational stability improvement, allowing its reuse, increased proteolysis resistance and immunogenicity elimination. The most recent applications of confined ASNase in nanomaterials are reviewed for the first time, simultaneously providing prospects in the described fields of application.

Spirulina maxima L-asparaginase: Immobilization, Antiviral and Antiproliferation Activities

BACKGROUND

L-asparaginase (L-AsnA) enzyme has gained significant attention in the food, biocatalysts and pharmaceutics industry. It (L-AsnA) has been widely used in food processing industries as a promising acrylamide mitigating agent and as a therapeutic agent in the treatment of certain human cancers.

OBJECTIVE

Based on US Patent (4,433,054; 1984), L-asparaginase (L-AsnA) enzyme is immobilized by admixing the active enzyme on the polysaccharide to be in a gel form. The storage stability of immobilized L-AsnA enzyme and its anti-proliferation and antiviral activity were determined.

METHODS

In the present study, S. maxima was cultured at large scales (300 liter) for the production of enough extracellular L-asparaginase (L-AsnA) using modified (high N concentration) Zarrouk medium as we reported in a previous study. L-AsnA was immobilized on natural polymers, as agar cake beads, agarose pieces and gelatin blocks, in order to evaluate the efficiency of physical entrapment techniques. Anti-proliferation properties of L-AsnA against lung carcinoma A549, hepatocellular carcinoma Hep-G2 and prostate carcinoma PC3 human cancer cell lines were assessed by the MTT cell viability method. In addition, the antiviral activity against Coxsackie B3 (CSB3) Virus was assessed.

RESULTS

The highest L-AsnA immobilized activity and immobilization yield were achieved with agar cakes bead. The purified S. maxima L-AsnA showed good antiviral activity against Coxsackie B3 (CSB3) Virus in a dose-dependent manner with an IC50 value 17.03 μg/ml. The antiviral mode of action is presumably due to their capability of inhibiting attachment, blocking the adsorption and penetration event of the viral replication cycle with 89.24%, 72.78% and 72.78%, respectively. Also, S. maxima L-AsnA showed anti-proliferation effect against lung carcinoma A549, hepatocellular carcinoma Hep-G2 and prostate carcinoma PC3 human cancer cell lines, with an IC50 of 22.54, 24.65 and 56.61 μg/ml, respectively.

CONCLUSION

It is interesting to favor L-asparaginase of S. maxima which showed antiviral activity and anti-proliferation effect against different types of human cell lines. Thus, S. maxima microalgae might be a good source for L-AsnA enzymes and can be immobilized on natural polymers.