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L-Asparaginase (ASNase) exerts its main anticancer activity by depleting L-Asparagine (Asn). In dogs with lymphomas, ASNase is commonly administered intramuscularly or subcutaneously and incorporated in multiagent protocols. The goal of this study is to assess plasma asparagine depletion and ASNase activity after intravenous administration of ASNase. A secondary goal was to investigate the toxicity and clinical response after intravenous infusion of high-dose ASNase. The study included ten dogs with naïve multicentric lymphoma. All dogs were immunophenotyped, staged, and followed to death. ASNase was administered intravenously at a dose of 3000 IU/kg on a Monday-Wednesday-Friday schedule. ASNase activity and Asn concentration were assessed on days 1, 3, and 5, before and after infusion, and on day 21. Clinical response and toxicity were assessed on weeks 2, 6, and 10, and then every 4 weeks until relapse. Plasma ASNase activity was sufficient to induce and maintain Asn depletion after and between each administration. The activity at day 21 was below detection in 8/10 dogs, and Asn was still depleted in 4/10 dogs. The ORR was 60% (respectively 40%CR and 20%PR). The median TTP was 31 days (95% CI 0–70). All dogs underwent rescue treatment with a multiagent protocol (8 CHOP and 2 LOPP). The median TTP after starting a rescue was not reached after 392 days. Mild gastrointestinal toxicity occurred in 30% of dogs, while hematologic toxicity or hypersensitivity reactions did not occur. ASNase activity and depletion of Asn were clinically adequate. The clinical efficacy was comparable with previous literature. The intravenous infusion of high-dose ASNase was well tolerated with only mild and self-limiting toxicity. [ABSTRACT FROM AUTHOR]

Introduction: L-Asparaginase (L-Asp) is a key drug in the treatment of acute lymphoblastic leukemia (ALL); however, it is commonly associated with the occurrence of adverse events (AE). Risk factors such as age, sex, nutritional status, and some single nucleotide variants (SNVs) in specific genes could be related to hypersensitivity reactions to L-Asp. The objective of this study was to identify the influence of individual characteristics and three SNVs in the GRIA1 and NFATC2 genes on the occurrence of the most significant adverse events caused by the use of L-Asp in Mexican children with ALL. Methods: Eighty-five children from ages 0–17 years old diagnosed with ALL were included. The patients were treated at two hospital centers in Mexico. The SNV genotypes of the GRI1A and NFATC2 genes studied were examined using real-time qPCR. The evaluation of AE was carried out according to the Common Terminology Criteria for adverse events, and the determination of anti-L-Asp antibodies was conducted using Western blot immunoassay. Results: Homozygosity (AA) of the GRIA1 rs4958351 SNV was significantly associated with the occurrence of AE with the use of L-Asp (OR = 4.05; 95% CI = 1.06 to 15.40, p = 0.04) and was strongly associated with the development of anti-L-Asp antibodies (OR = 3.4375, 95% CI = 1.04 to 11.25, p = 0.04). With this, we found a significant risk association for the SNV rs4958351 of the GRIA1 gene. On the other hand, we did not find significant risk associations for the GRIA1 rs6889909 and NFATC2 rs6021191 SNVs, although other populations have shown a significant risk. Discussion: Our study has some limitations, such as the small sample size, the heterogeneity in adverse events due to the patients' different regions of origin, and the limited ability to conduct a more detailed follow-up on pancreatitis. Additionally, since no significant associations were found between the NFATC2 rs6021191 and GRIA1 rs6889909 SNVs and the development of adverse events or the presence of antibodies due to the use of L-Asp, it is necessary to investigate new specific SNVs that may improve the efficacy and safety of treatment in Mexican children with ALL. [ABSTRACT FROM AUTHOR]

A significant challenge associated with the therapeutic use of L-ASP for treatment of tumors is its rapid clearance from plasma. Effectiveness of L-ASP is limited by the dose-dependent toxicity. Therefore, new approaches are being developed for L-ASP to improve its therapeutic properties. One of the approaches to improve properties of the enzymes, including L-ASP, is immobilization on various types of biocompatible polymers. Immobilization of enzymes on a carrier could improve stability of the enzyme and change duration of its enzymatic activity. Bacterial cellulose (BC) is a promising carrier for various drugs due to its biocompatibility, non-toxicity, high porosity, and high drug loading capacity. Therefore, this material has high potential for application in biomedicine. Native BC is known to have a number of disadvantages related to structural stability, which has led to consideration of the modified BC as a potential carrier for immobilization of various proteins, including L-ASP. In our study, a BC–chitosan composite in which chitosan is cross-linked with glutaraldehyde was proposed for immobilization of L-ASP. Physicochemical characteristics of the BC–chitosan films were found to be superior to those of native BC films, resulting in increase in the release time of L-ASP in vitro from 8 to 24 h. These films exhibited prolonged toxicity (up to 10 h) against the melanoma cell line. The suggested strategy for A-ASP immobilization on the BC–chitosan films could be potentially used for developing therapeutics for treatment of surface types of cancers including melanomas. [ABSTRACT FROM AUTHOR]

AbstractL-asparaginase (L-Asp) is an essential enzyme in the treatment of patients with Acute Lymphoblastic Leukemia (ALL), commonly associated with adverse events (AE). Knowing the pharmacokinetic and pharmacodynamic (PK/PD) parameters of L-Asp as well as its relationship with the development of AE is an important strategy in the search to improve the efficacy and safety of the treatment. Seventy-four children with ALL that were being treated with L-Asp, were included. One to three blood samples were randomly obtained from each patient, at times from 0 to 30 hours, until completing a total of 211 samples. The L-Asp activity and the Asparagine (Asp) concentration were quantified, in addition, the presence of anti-L-Asp antibodies (Anb) was determined. A population PK/PD model of L-Asp was developed to determine the association of covariates with PK/PD parameters. The presence of Anb was associated with the increase in L-Asp clearance (CL) and with the decrease of volume of distribution 1 (V1). On the other hand, female sex was significantly associated with the increase of V1, while the age from 1 to 6 years was significantly associated with the increase of V1. The presence of Anb as well as the female sex were related to the increase IC50 (concentration-needed to deplete-50% of Asp). Patients who presented Asp depletion before the first 24 hours after administration presented pancreatitis, this could be a risk marker. Significant results were found in this study, use of these results may contribute to the safe and effective use of L-Asp. [ABSTRACT FROM AUTHOR]

In the present investigation, a novel thermophilic L-asparaginase (Asn_PA) from Pseudomonas aeruginosa CSPS4 was investigated to explore its structural insights at elevated temperatures. Sequence analysis of Asn_PA depicted three conserved motifs (VVILATGGTIAG, DGIVITHGTDTLEETAYFL, and, LRKQGVQIIRSSHVNAGGF), of them, two motifs exhibit catalytically-important residues i.e., T45 and T125. A homology modelling-based structure model for Asn_PA was generated with 4PGA as the top-matched template. The predicted structure was validated and energy was minimized. Molecular docking was carried out cantered at the active site for asparagine and glutamine as its substrate ligands. The enzyme–substrate interaction analysis showed binding affinities of – 4.8 and – 4.1 kcal/mol for asparagine and glutamine respectively. Molecular dynamics (MD) simulation studies showed a better stability of Asn_PA at temperatures of 60 °C, over 40, 50 and, 80 °C, making this enzyme a novel L-asparaginase from other mesophilic P. aeruginosa strain. The trajectory analysis showed that RMSD, Rg, and, SASA values correlate well with each other in the different tested temperatures during the MD analysis. Thus, the present findings encourage extensive characterization of the Asn_PA using laboratory experiments to understand the structural behavior of the active site loop in an open or closed state with and without the substrate molecules. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Glutaraldehyde is the conventionally used cross‐linker for the activation and cross‐linking of support matrices used in enzyme immobilization. However, the toxic nature of glutaraldehyde makes it unsafe for food applications, propelling the need for nontoxic cross‐linkers. Genipin reacts with the primary and secondary amines generating a dark‐blue colored pigment and is an attractive alternative to glutaraldehyde as a cross‐linker for enzyme immobilization. Apart from its excellent cross‐linking properties, genipin possesses added advantages over glutaraldehyde such as proven health benefits, biocompatibility, and biodegradability. The present study explores the application of chitosan beads cross‐linked with the natural and nontoxic agent, genipin, for immobilizing l‐asparaginase, aimed at its subsequent use in mitigating acrylamide formation in food products. The immobilized l‐asparaginase exhibited improved functionalities such as stability, reusability, and reduction in acrylamide formation in deep‐fried cassava chips. One of the limitations observed during application in the food process was the mechanical fragility of the chitosan beads during speedy stirring. This can be overcome by increasing the concentration and time of contact of the coagulant bath during the formation of chitosan beads. The drying of the enzyme‐bound chitosan beads will also lead to shrinkage and prevent breakage during stirring. This study conclusively demonstrated the applicability of immobilizing l‐asparaginase on genipin cross‐linked chitosan beads in food‐related processes. [ABSTRACT FROM AUTHOR]

Among the fungal iolates, isolate JK12 and ChL11 showed high L-ASNase activity (34.04 ± 1.83a U/ml and 30.84 ± 0.53b U/ml, respectively) with reduced L-GLNase co-activity (4.95 ± 0.28c U/ml and 4.80 ± 0.02d U/ml, respectively). Sequencing of the internal transcribed spacer (ITS) region of these isolates identified them as Candida palmioleophila isolate JK12 (≥99% identity with Candida genus) and Trichosporon asahii isolate ChL11 (≥98% identity with Trichosporon genus). Moreover, these isolates exhibited distinct preferences for carbon (C) and nitrogen (N) sources, as well as culture conditions for L-ASNase production. C. palmioleophila isolate JK12 demonstrated the highest L-ASNase production in fructose and yeast extract (67.6 ± 0.04a U/ml and 51.4 ± 0.04a U/ml, respectively), following 96 h of incubation at 25°C (43.8 ± 1.22a U/ml, 55.8 ± 0.02a U/ml, respectively), with an agitation speed of 100 rpm (59.9 ± 0.04a U/ml). On the other hand, T. asahii isolate ChL11 exhibited maximum L-ASNase production in sucrose and L-asparagine (64.2 ± 0.08a U/ml and 63.6 ± 0.01a U/ml, respectively), after 120 h of incubation at 35°C.Conclusions The fungal isolates T. asahii isolate ChL11 and C. palmioleophila isolate JK12 have been identified as promising L-ASNase sources of safer therapeutic prospects in cancer therapy due to the reduced GLNase co-activity. [ABSTRACT FROM AUTHOR]

Background: L-asparaginase (L-ASNase) is an essential enzyme used to treat acute lymphoblastic leukemia (ALL) by depleting L-asparagine, a vital nutrient for leukemia cells. However, its clinical use is challenged by adverse effects linked to its bacterial origin and L-glutaminase (L-GLNase) co-activity. This study aims to identify fungi capable of producing L-ASNase with reduced L-GLNase co-activity. Results: Among the fungal iolates, isolate JK12 and ChL11 showed high L-ASNase activity (34.04 ± 1.83a U/ml and 30.84 ± 0.53b U/ml, respectively) with reduced L-GLNase co-activity (4.95 ± 0.28c U/ml and 4.80 ± 0.02d U/ml, respectively). Sequencing of the internal transcribed spacer (ITS) region of these isolates identified them as Candida palmioleophila isolate JK12 (≥99% identity with Candida genus) and Trichosporon asahii isolate ChL11 (≥98% identity with Trichosporon genus). Moreover, these isolates exhibited distinct preferences for carbon (C) and nitrogen (N) sources, as well as culture conditions for L-ASNase production. C. palmioleophila isolate JK12 demonstrated the highest L-ASNase production in fructose and yeast extract (67.6 ± 0.04a U/ml and 51.4 ± 0.04a U/ml, respectively), following 96 h of incubation at 25°C (43.8 ± 1.22a U/ml, 55.8 ± 0.02a U/ml, respectively), with an agitation speed of 100 rpm (59.9 ± 0.04a U/ml). On the other hand, T. asahii isolate ChL11 exhibited maximum L-ASNase production in sucrose and L-asparagine (64.2 ± 0.08a U/ml and 63.6 ± 0.01a U/ml, respectively), after 120 h of incubation at 35°C. Conclusions: The fungal isolates T. asahii isolate ChL11 and C. palmioleophila isolate JK12 have been identified as promising L-ASNase sources of safer therapeutic prospects in cancer therapy due to the reduced GLNase co-activity.How to cite: Sisay T, Mobegi VA, Wachira S, et al. Isolation and characterization of fungi producing L-asparaginase with reduced L-glutaminase activity from soil samples. Electron J Biotechnol 2024. https://doi.org/10.1016/j.ejbt.2024.05.002.

Cerebral venous sinus thrombosis (CVST) and hyperlipidemia are severe complications of L-Asparaginase (L-Asp) during the treatment of B-cell acute lymphoblastic leukemia (B-ALL). Herein, we reported a 9-year-old B-ALL boy who underwent abnormal hypertriglyceridemia and CVST presenting as seizures and disturbance of consciousness twice during the induction therapy. Fortunately, he survived treatment with anticoagulant and lipid-lowering therapy. No thrombophilia-related gene mutation was detected, but a heterozygous mutation in lipoprotein lipase (LPL) gene was identified. His neurological symptoms were managed with short-term anticoagulant therapy and long-term lipid-lowering therapy. This case illustrated the manifestation and potential pathogenesis of CVST and highlighted the essentiality of screening baseline lipid profile and dyslipidemia- and thrombophilia-related gene mutation.

Asparagine synthetase (ASNS) catalyzes the biosynthesis of asparagine from aspartate and glutamine. Cells lacking ASNS, however, are auxotrophic for asparagine. Use of L-asparaginase to promote asparagine starvation in solid tumors with low ASNS levels, such as pancreatic ductal adenocarcinoma (PDAC), is a rationale treatment strategy. However, tumor cell resistance to L-asparaginase has limited its clinical utility. Our preclinical studies show that RAS/MAPK signaling circumvents L-asparaginase-induced tumor killing, but L-asparaginase and MEK inhibition potentiated tumor killing; suggesting that this combination may provide meaningful clinical benefit to patients with PDAC. This Phase I trial (NCT05034627) will evaluate the safety and tolerability of the MEK inhibitor, cobimetinib, in combination with pegylated L-asparaginase, L calaspargase pegol-mknl, in patients with locally-advanced or metastatic PDAC. Article highlights Introduction Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer with poor prognosis. The majority (50–80%) of PDAC lack asparagine synthetase and ability to synthesize asparagine; and are dependent on extracellular sources of asparagine. Use of L-asparaginase to promote asparagine starvation in solid tumors can be exploited as a rationale treatment strategy. Study rationale Under conditions of nutrient stress, aberrant RAS/MEK/ERK signaling induces ATF4 and in turn, asparagine synthetase to bolster intracellular biosynthesis of asparagine. Targeted inhibition of RAS/MEK/ERK signaling along with an L-asparaginase has the potential to provide meaningful clinical benefit to patients with advanced PDAC. There is no prior research that has provided a safety profile for a MEK inhibitor in combination with L-asparaginase. Design This Phase IB trial will evaluate the safety and tolerability of the MEK inhibitor, cobimetinib, in combination with the pegylated L-asparaginase, L calaspargase pegol-mknl, in patients with locally-advanced or metastatic PDAC. The trial uses a Bayesian optimal interval design to assess the maximum tolerated dose for combining cobimetinib and calaspargase pegol-mknl. Objectives The primary end point estimates the incidence of dose limiting toxicities associated with combination regimen of cobimetinib and calaspargase pegol-mknl. Secondary objectives estimate the preliminary objective response rate and clinical benefit rate. Key eligibility Adults with locally-advanced or metastatic PDAC that have progressed on, been intolerant to, or refused systemic therapy that is consistent with institutional standards (e.g., Gemcitabine-based, or FOLFIRINOX). Study procedures A maximum of 15 patients will be enrolled in cohorts of 3 to receive their assigned dose of calaspargase pegol-mknl and cobimetinib. Up to 6 core-needle biopsies at baseline and on Cycle 2 Day 14. [ABSTRACT FROM AUTHOR]

L-asparaginase (ASNase, E.C. 3.5.1.1) catalyzes the deamination of L-asparagine to L-aspartic acid and ammonia and is widely used in medicine to treat acute lymphocytic leukemia. It also has significant applications in the food industry by inhibiting acrylamide formation. In this study, we characterized a thermostable ASNase from the hyper thermophilic strain, Pyrococcus yayanosii CH1. The recombinant enzyme (PyASNase) exhibited maximal activity at pH 8.0 and 85 °C. Moreover, PyASNase demonstrated promising thermostability across temperatures ranging from 70 to 95 °C. The kinetic parameters of PyASNase for L-asparagine were a Km of 6.3 mM, a kcat of 1989s−1, and a kcat/Km of 315.7 mM−1 s−1. Treating potato samples with 10 U/mL of PyASNase at 85 °C for merely 10 min reduced the acrylamide content in the final product by 82.5%, demonstrating a high efficiency and significant advantage of PyASNase in acrylamide inhibition. [ABSTRACT FROM AUTHOR]

L-asparaginase is an essential enzyme used in cancer treatment, but its production faces challenges like low yield, high cost, and immunogenicity. Recombinant production is a promising method to overcome these limitations. In this study, response surface methodology (RSM) was used to optimize the production of L-asparaginase 1 from Saccharomyces cerevisiae in Escherichia coli K-12 BW25113. The Box-Behnken design (BBD) was utilized for the RSM modeling, and a total of 29 experiments were conducted. These experiments aimed to examine the impact of different factors, including the concentration of isopropyl-b-LD-thiogalactopyranoside (IPTG), the cell density prior to induction, the duration of induction, and the temperature, on the expression level of L-asparaginase 1. The results revealed that while the post-induction temperature, cell density at induction time, and post-induction time all had a significant influence on the response, the post-induction time exhibited the greatest effect. The optimized conditions (induction at cell density 0.8 with 0.7 mM IPTG for 4 h at 30 °C) resulted in a significant amount of L-asparaginase with a titer of 93.52 μg/mL, which was consistent with the model-based prediction. The study concluded that RSM optimization effectively increased the production of L-asparaginase 1 in E. coli, which could have the potential for large-scale fermentation. Further research can explore using other host cells, optimizing the fermentation process, and examining the effect of other variables to increase production. [ABSTRACT FROM AUTHOR]

L-Asparaginase (EC 3.5.1.1) primarily catalyzes the hydrolysis of Asn into ammonium and L-Asp and has wide applications in various industrial sectors. This protein has several sources, including microorganisms, plants, and the serum of certain rodents. Currently, L-asparaginase is primarily produced through biotechnology using bacteria and fungi. Genetic engineering methods are employed to create more stable enzymes than those available for the wild type. Given the extensive industrial use of L-asparaginase, optimization, and purification techniques are utilized to increase ex vivo enzyme production. The objective of this study is to comprehensively review the current literature on the production of L-asparaginase from diverse sources and using various methodologies. [ABSTRACT FROM AUTHOR]

L-asparaginases (ASP) and Doxorubicin (Dox) are both used in the treatment of leukemia, including in combination. We have attempted to investigate if their combination within the same targeted delivery vehicle can make such therapy more efficacious. We assembled a micellar system, where the inner hydrophobic core was loaded with Dox, while ASP would absorb at the surface due to electrostatic interactions. To make such absorption stronger, we conjugated the ASP with oligoamines, such as spermine, and the lipid components of the micelle—lipoic and oleic acids—with heparin. When loaded with Dox alone, the system yielded about a 10-fold improvement in cytotoxicity, as compared to free Dox. ASP alone showed about a 2.5-fold increase in cytotoxicity, so, assuming additivity of the effect, one could expect a 25-fold improvement when the two agents are applied in combination. But in reality, a combination of ASP + Dox loaded into the delivery system produced a synergy, with a whopping 50× improvement vs. free individual component. Pharmacokinetic studies have shown prolonged circulation of micellar formulations in the bloodstream as well as an increase in the effective concentration of Dox in micellar form and a reduction in Dox accumulation to the liver and heart (which reduces hepatotoxicity and cardiotoxicity). For the same reason, Dox's liposomal formulation has been in use in the treatment of multiple types of cancer, almost replacing the free drug. We believe that an opportunity to deliver a combination of two types of drugs to the same target cell may represent a further step towards improvement in the risk–benefit ratio in cancer treatment. [ABSTRACT FROM AUTHOR]

This study profiled the various endophytic fungi isolated from the orchid Cymbidium sp. and their L-asparaginase production and antioxidant potential. The L-asparaginase production was first screened through qualitative plate screening then quantified by the Nesslerization method. The antioxidant potential was quantified via the 2,2-diphenyl-1-picrylhydrazyl assay. A total of 30 endophytic fungi were isolated and all fungal isolates exhibited various degrees of radical scavenging activities (45.28% to 76.4%). Isolate Lasiodiplodia theobromae (C11) had the highest antioxidant capacity, represented by the lowest IC50 value (5.75 mg/mL) and highest ascorbic acid equivalent antioxidant capacity value (12.17 mg/g). Additionally, 16 isolates produced L-asparaginase (53.33%), which includes primarily species of Fusarium proliferatum, Fusarium fujikuroi, Fusarium incarnatum, and Fusarium oxysporum. A new isolate has also been discovered from Cymbidium orchid, Buergenerula spartinae (C28), which showed the highest L-asparaginase activity (1.736 unit/mL). These findings supported the postulation that medicinal species of Orchidaceae such as Cymbidium sp. harbor endophytes that are producers of L-asparaginase and antioxidants with various potential applications. [ABSTRACT FROM AUTHOR]

Background: This study aimed to assess Pseudomonas fluorescens-purified L-Asparaginase's effectiveness as a broad-spectrum inhibitor of biofilm producers in dental decays. Methods: The 16S rRNA sequence was used to build a phylogenetic tree to calculate the evolutionary distance between the isolated bacterial strain SW3 and other species. The evolutionary history was inferred by using the neighbor-joining approach. Results: The bacteria were identified from dental decays, including Staphylococcus aureus, Streptococcus mutans, Streptococcus oralis, and Streptococcus mitis. Each one of these isolates showed different degrees of biofilm development. Purified L-Asparaginase inhibited the most potent Gram-positive biofilm-forming bacteria (biofilm producers) with higher inhibition percentages against Streptococcus oralis and Streptococcus mitis, 65 - 73.8 % and 54.7 - 63%, respectively. The inhibition percentages increased with increasing concentration and reached up to 74 - 81% with Streptococcus oralis and 66 - 74% with Streptococcus mitis, while SW3 bacteria showed (100%). This strain was suggested SW3 (Pseudomonas spp.). Pseudomonas fluorescens bacterial strain isolated from rhizosphere soil produced extracellular L-Asparaginase when grown on as a substrate. L-Asparaginase was purified to homogeneity by using ammonium sulfate at 60% saturation, followed by gel filtration chromatography on a sephadex G-100 column, with a recovery yield of 49% and a purification fold of 2.22. Conclusions: L-Asparaginase had a promising use for removing and avoiding biofilm growth, implying that it might be used in the dental industry in the future. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HAp) is a calcium phosphate ceramic, widely used as a matrix for protein chromatography. The crystal structure of HAp is amenable to a wide range of substitutions, thus allowing for the alteration of its properties. In this study, nickel‐ion substituted HAp (NiSHAp) was synthesized using a wet‐precipitation method, followed by spray drying. This resulted in the structural incorporation of nickel ions within well‐defined microspheres, which were suitable for chromatographic applications. The chromatographic experiments were conducted with NiSHAp and compared with spray‐dried hydroxyapatite (SHAp) matrices. Protein purification experiments were conducted using refolded recombinant L‐asparaginase (L‐Asp), which was produced as inclusion bodies in Escherichia coli. The results showed that NiSHAp effectively adsorbed L‐Asp, which was selectively eluted using a phosphate buffer, surpassing the efficiency of imidazole‐based elution. In contrast, SHAp showed weaker binding and lower selectivity. The significance of this study lies in developing a scalable NiSHAp matrix for protein purification, especially for large‐scale applications. The NiSHAp matrix offers a cost‐effective alternative to commercial immobilized metal affinity chromatography (IMAC) adsorbents, especially for purifying His‐tagged proteins. This innovative approach exhibits the advantages of mixed‐mode chromatography by combining the properties of hydroxyapatite and IMAC in a single matrix, with the potential of improved industrial‐scale protein purification. [ABSTRACT FROM AUTHOR]

Purpose: L-asparaginase has been widely recognized as a critical component in the treatment of various types of lymphoproliferative disorders, since its introduction in 1960s. However, its use in some cases leads to allergic reactions rendering the continuation of treatment unfeasible. Thus, the development of L-asparaginase from alternative sources or the production of engineered enzymes have always been considered. This study aimed to produce and evaluate a novel enzyme designed based on the sequence of L-asparaginase from Escherichia coli bacteria with Y176F/S241C mutations. Methods: The Y176F/S241C mutant L-asparaginase was successfully expressed as the GST-fusion protein in E. coli , and then was subjected to affinity and size exclusion chromatography. The activity of the purified enzyme was determined based on the released ammonia as the result of substrate hydrolysis using Nessler's reagent. Chemical denaturation experiment in the presence of increasing concentration of guanidinium chloride was applied to determine the folding stability of the purified enzyme. Results: The mutant enzyme was purified with an efficiency of 77-fold but at a low recovery of 0.7%. The determined kinetic parameters Km, Vmax, kcat, specific activity and catalytic efficiency were 13.96 (mM), 2.218 (mM/min), 273.9 (min-1), 237.8 (IU/mg) and 19.62 (mM-1 min-1), respectively. Moreover, unfolding free energy determined by guanidinium chloride induced denaturation for mutated and commercial L-asparaginase enzymes were 8421 J/mol and 5274 J/mol, respectively. Conclusion: The mutant enzyme showed improved stability over the wild-type. Although the expression level and recovery were low, the mutant L-asparaginase demonstrated promising activity and stability, with potential clinical and industrial applications. [ABSTRACT FROM AUTHOR]

Summary: B‐cell precursor acute lymphoblastic leukaemia (BCP‐ALL) blasts strictly depend on the transport of extra‐cellular asparagine (Asn), yielding a rationale for L‐asparaginase (ASNase) therapy. However, the carriers used by ALL blasts for Asn transport have not been identified yet. Exploiting RS4;11 cells as BCP‐ALL model, we have found that cell Asn is lowered by either silencing or inhibition of the transporters ASCT2 or SNAT5. The inhibitors V‐9302 (for ASCT2) and GluγHA (for SNAT5) markedly lower cell proliferation and, when used together, suppress mTOR activity, induce autophagy and cause a severe nutritional stress, leading to a proliferative arrest and a massive cell death in both the ASNase‐sensitive RS4;11 cells and the relatively ASNase‐insensitive NALM‐6 cells. The cytotoxic effect is not prevented by coculturing leukaemic cells with primary mesenchymal stromal cells. Leukaemic blasts of paediatric ALL patients express ASCT2 and SNAT5 at diagnosis and undergo marked cytotoxicity when exposed to the inhibitors. ASCT2 expression is positively correlated with the minimal residual disease at the end of the induction therapy. In conclusion, ASCT2 and SNAT5 are the carriers exploited by ALL cells to transport Asn, and ASCT2 expression is associated with a lower therapeutic response. ASCT2 may thus represent a novel therapeutic target in BCP‐ALL. [ABSTRACT FROM AUTHOR]

Summary: Physiologically based pharmacokinetic (PBPK) modelling is an alternative modelling technique that is increasingly used in pharmacokinetics. Due to its nature, it can be complementarily employed to population pharmacokinetics, especially when it comes to small population size. Here, we report the proof of concept of its application to accurately describe the pharmacokinetics of a recombinant L‐asparaginase in paediatric patients with acute lymphoblastic leukaemia. Data from two randomized, double‐blind, phase II/III clinical studies (MC‐ASP.4/ALL; MC‐ASP.5/ALL) were included to setup and evaluate the final model, respectively. Final population values for basic pharmacokinetic parameters were calculated (clearance: 0.0569 L/h/19.5 kg, volume of distribution: 1.251 L, half‐life: 18.5 h, trough concentration: 140.9 IU/L). Pharmacokinetic parameter prediction as well as predictive performance of the model proofed to be comparable to a separately developed population pharmacokinetic model with 13% deviation in predicted median L‐asparaginase trough levels. To the best of our knowledge, this is the first whole‐body PBPK model of a non‐antibody therapeutic protein. [ABSTRACT FROM AUTHOR]

Amino acid deprivation therapy (AADT) is a novel anticancer therapy, considered nontoxic and selective. Thermophilic L-asparaginase enzymes display high stability and activity at elevated temperatures. However, they are of limited use in clinical applications because of their low substrate affinity and reduced activity under physiological conditions, which may necessitate an improved dosage, leading to side effects and greater costs. Thus, in an attempt to improve the activity of L-Asn at 37 °C, with the use of a semi-rational design, eight active-site mutants of Thermococcus litoralis DSM 5473 L-asparaginase Tli10209 were developed. T70A exhibited a 5.11-fold increase compared with the wild enzyme in physiological conditions. Double-mutant enzymes were created by combining mutants with higher hydrolysis activity. T70A/F36Y, T70A/K48L, and T70A/D50G were enhanced by 5.59-, 6.38-, and 5.58-fold. The immobilized enzyme applied in MCF-7 breast cancer cells only required one-seventh of the dose of the free enzyme to achieve the same inhibition rate under near-infrared irradiation. This provides a proof of concept that it is possible to reduce the consumption of L-Asn by improving its activity, thus providing a method to manage side effects. [ABSTRACT FROM AUTHOR]

We succeeded in homogeneously expressing and purifying l-asparaginase from Latilactobacillus sakei LK-145 (Ls-Asn1) and its mutated enzymes C196S, C264S, C290S, C196S/C264S, C196S/C290S, C264S/C290S, and C196S/C264S/C290S-Ls-Asn1. Enzymological studies using purified enzymes revealed that all cysteine residues of Ls-Asn1 were found to affect the catalytic activity of Ls-Asn1 to varying degrees. The mutation of Cys196 did not affect the specific activity, but the mutation of Cys264, even a single mutation, significantly decreased the specific activity. Furthermore, C264S/C290S- and C196S/C264S/C290S-Ls-Asn1 almost completely lost their activity, suggesting that C290 cooperates with C264 to influence the catalytic activity of Ls-Asn1. The detailed enzymatic properties of three single-mutated enzymes (C196S, C264S, and C290S-Ls-Asn1) were investigated for comparison with Ls-Asn1. We found that only C196S-Ls-Asn1 has almost the same enzymatic properties as that of Ls-Asn1 except for its increased stability for thermal, pH, and the metals NaCl, KCl, CaCl2, and FeCl2. We measured the growth inhibitory effect of Ls-Asn1 and C196S-Ls-Asn1 on Jurkat cells, a human T-cell acute lymphoblastic leukemia cell line, using l-asparaginase from Escherichia coli K-12 as a reference. Only C196S-Ls-Asn1 effectively and selectively inhibited the growth of Jurkat T-cell leukemia, which suggested that it exhibited antileukemic activity. Furthermore, based on alignment, phylogenetic tree analysis, and structural modeling, we also proposed that Ls-Asn1 is a so-called “Type IIb” novel type of asparaginase that is distinct from previously reported type I or type II asparaginases. Based on the above results, Ls-Asn1 is expected to be useful as a new leukemia therapeutic agent. [ABSTRACT FROM AUTHOR]

In this study, a new recombinant L-asparaginase from Geobacillus kaustophilus was covalently immobilized on ReliZyme EA403 (Relizyme/EA@GkASNase) and ReliZyme HA403 (Relizyme/HA@GkASNase) supports, and the free and immobilized L-asparaginases were used for their acrylamide mitigation performances in a food model system. The immobilization was confirmed by fourier-transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy analysis. The optimum pH was determined as 8.5 for all the free and immobilized L-asparaginase samples. The optimum temperature was determined as 55 °C for the free enzyme and 60 °C for both the immobilized samples. The thermal stability of L-asparaginase was increased by 17.6 and 37.2 folds at 60 °C for Relizyme/EA@GkASNase and Relizyme/HA@GkASNase, respectively. Relizyme/EA@GkASNase and Relizyme/HA@GkASNase showed 16% and 43% of the catalytic efficiency of free GkASNase. The acrylamide mitigation performances of free and immobilized L-asparaginase samples were investigated using the L-asparagine–starch food model system and the formed acrylamide was completely mitigated in 1 h for all the L-asparaginase samples. Both the immobilized L-asparaginase samples retained at least 80% of their activities after five reuses. Hence, the immobilized GkASNase preparations can be potentially used in heat-treated food industries to remove acrylamide. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

IntroductionL-Asparaginase (L-Asp) is a key drug in the treatment of acute lymphoblastic leukemia (ALL); however, it is commonly associated with the occurrence of adverse events (AE). Risk factors such as age, sex, nutritional status, and some single nucleotide variants (SNVs) in specific genes could be related to hypersensitivity reactions to L-Asp. The objective of this study was to identify the influence of individual characteristics and three SNVs in the GRIA1 and NFATC2 genes on the occurrence of the most significant adverse events caused by the use of L-Asp in Mexican children with ALL.MethodsEighty-five children from ages 0–17 years old diagnosed with ALL were included. The patients were treated at two hospital centers in Mexico. The SNV genotypes of the GRI1A and NFATC2 genes studied were examined using real-time qPCR. The evaluation of AE was carried out according to the Common Terminology Criteria for adverse events, and the determination of anti-L-Asp antibodies was conducted using Western blot immunoassay.ResultsHomozygosity (AA) of the GRIA1 rs4958351 SNV was significantly associated with the occurrence of AE with the use of L-Asp (OR = 4.05; 95% CI = 1.06 to 15.40, p = 0.04) and was strongly associated with the development of anti-L-Asp antibodies (OR = 3.4375, 95% CI = 1.04 to 11.25, p = 0.04). With this, we found a significant risk association for the SNV rs4958351 of the GRIA1 gene. On the other hand, we did not find significant risk associations for the GRIA1 rs6889909 and NFATC2 rs6021191 SNVs, although other populations have shown a significant risk.DiscussionOur study has some limitations, such as the small sample size, the heterogeneity in adverse events due to the patients’ different regions of origin, and the limited ability to conduct a more detailed follow-up on pancreatitis. Additionally, since no significant associations were found between the NFATC2 rs6021191 and GRIA1 rs6889909 SNVs and the development of adverse events or the presence of antibodies due to the use of L-Asp, it is necessary to investigate new specific SNVs that may improve the efficacy and safety of treatment in Mexican children with ALL.

Abstract 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.

L-asparaginase is one of the most effective drugs in pediatric and adult acute lymphoblastic leukemia treatment. But drug side effects are an important problem. pancreatitis and pancreatic necrosis are not common (2–18 %) complication, but high chance of severe disease with fatal outcome make to bring in careful attention of pediatric oncologists-hematologists, surgeons, intensivists, radiologists. Recognizing multidisciplinary importance of this problem, at June 21st, 2023 at Morozov Children’s Clinical hospital a Round table on pancreatitis/pancreatic necrosis after L-asparaginase use was organized. This article presents expert recommendations from federal and regional clinics in diagnosis and treatment of such severe complication.

Abstract Background Thromboembolic complications are well known in the treatment of childhood acute lymphoblastic leukemia. Over the years it has not been possible to reach a consensus on a possible prophylaxis of thromboembolic events during intensive therapy. Only the administration of enoxaparin was able to achieve evidence in the literature to date. Methods In this retrospective study, 173 childhood leukemia patients were treated over 20 years with a thromboembolic prophylaxis including enoxaparin and AT III during induction therapy with L-asparaginase and cortisone. Results We here report the effectiveness of administration of enoxaparin and AT III in childhood leukemia, showing a strikingly low prevalence of deep vein thrombosis (2.9%). Especially in adolescent patients, a particularly great need for AT III was demonstrated. Conclusions We recommend thromboembolic prophylaxis with enoxaparin and AT III substitution during induction/reinduction therapy with L-asparaginase and glucocorticosteroids, especially from adolescence onwards.

Abstract A dataset comprising metagenomes of outpatients (n = 28) with acute leukemia (AL) and healthy controls (n = 14) was analysed to investigate the associations between gut microbiota composition and metabolic activity and AL. According to the results obtained, no significant differences in the microbial diversity between AL outpatients and healthy controls were found. However, significant differences in the abundance of specific microbial clades of healthy controls and AL outpatients were found. We found some differences at taxa level. The relative abundance of Enterobacteriaceae, Prevotellaceae and Rikenellaceae was increased in AL outpatients, while Bacteirodaceae, Bifidobacteriaceae and Lachnospiraceae was decreased. Interestingly, the abundances of several taxa including Bacteroides and Faecalibacterium species showed variations based on recovery time from the last cycle of chemotherapy. Functional annotation of metagenome-assembled genomes (MAGs) revealed the presence of functional domains corresponding to therapeutic enzymes including l-asparaginase in a wide range of genera including Prevotella, Ruminococcus, Faecalibacterium, Alistipes, Akkermansia. Metabolic network modelling revealed potential symbiotic relationships between Veillonella parvula and Levyella massiliensis and several species found in the microbiota of AL outpatients. These results may contribute to develop strategies for the recovery of microbiota composition profiles in the treatment of patients with AL.

L-asparaginases are used in the treatment of acute lymphoblastic leukemia. The aim of this work was to compare the antiproliferative potential and proapoptotic properties of novel L-asparaginases from different structural classes, viz. EcAIII and KpAIII (class 2), as well as ReAIV and ReAV (class 3). The EcAII (class 1) enzyme served as a reference. The proapoptotic and antiproliferative effects were tested using four human leukemia cell models: MOLT-4, RAJI, THP-1, and HL-60. The antiproliferative assay with the MOLT-4 cell line indicated the inhibitory properties of all tested L-asparaginases. The results from the THP-1 cell models showed a similar antiproliferative effect in the presence of EcAII, EcAIII, and KpAIII. In the case of HL-60 cells, the inhibition of proliferation was observed in the presence of EcAII and KpAIII, whereas the proliferation of RAJI cells was inhibited only by EcAII. The results of the proapoptotic assays showed individual effects of the enzymes toward specific cell lines, suggesting a selective (time-dependent and dose-dependent) action of the tested L-asparaginases. We have, thus, demonstrated that novel L-asparaginases, with a lower substrate affinity than EcAII, also exhibit significant antileukemic properties in vitro, which makes them interesting new drug candidates for the treatment of hematological malignancies. For all enzymes, the kinetic parameters (Km and kcat) and thermal stability (Tm) were determined. Structural and catalytic properties of L-asparaginases from different classes are also summarized. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

L-asparaginase is an essential drug used to treat acute lymphoid leukemia (ALL), a cancer of high prevalence in children. Several adverse reactions associated with L-asparaginase have been observed, mainly caused by immunogenicity and allergenicity. Some strategies have been adopted, such as searching for new microorganisms that produce the enzyme and applying protein engineering. Therefore, this work aimed to elucidate the molecular structure and predict the immunogenic profile of L-asparaginase from Penicillium cerradense, recently revealed as a new fungus of the genus Penicillium and producer of the enzyme, as a motivation to search for alternatives to bacterial L-asparaginase. In the evolutionary relationship, L-asparaginase from P. cerradense closely matches Aspergillus species. Using in silico tools, we characterized the enzyme as a protein fragment of 378 amino acids (39 kDa), including a signal peptide containing 17 amino acids, and the isoelectric point at 5.13. The oligomeric state was predicted to be a homotetramer. Also, this L-asparaginase presented a similar immunogenicity response (T- and B-cell epitopes) compared to Escherichia coli and Dickeya chrysanthemi enzymes. These results suggest a potentially useful L-asparaginase, with insights that can drive strategies to improve enzyme production. [ABSTRACT FROM AUTHOR]

L-asparaginase is an important therapeutic biomolecule, used to treat lymphocytic leukemia. In the present study, Iodobacter sp. PCH194 genome was mined for new L-asparaginase (Id-ASNase II). In silico analysis including amino acid composition and pI revealed its sequence-based novelty and phylogenetic closeness to the commercial bacterial L-asparaginases. Subsequently, the gene was successfully cloned and overexpressed in Escherichia coli (E. coli BL21 DE3). The monomeric molecular weight of Id-ASNase II was 38 kDa with a native size of 150 kDa. Maximum L-asparaginase activity (80 U mg− 1) was achieved in 25 mM Tris-HCl buffer (pH 8.2) at 37 °C after 10 min of incubation. The enzyme was active in wide pH (5.0–11.0) and temperature ranges (4–70 °C). The half-life (t1/2) of the enzyme at 37 °C was 13.54 h, whereas Km, Vmax, kcat, and kcat/Km were 1.2 mM, 128 µmoles min− 1, 82 s− 1, and 63.1 s− 1 mM− 1, respectively. Id-ASNase II exhibited cytotoxicity against cancer cell line K562 (IC50 value 0.4 U mL− 1) leading to cell cycle arrest in the G2/M phase after treatment. Furthermore, 10 U Id-ASNase II led to a 57% acrylamide reduction in potato chips. Thus, the study discovered and characterized Id-ASNase II with potential applications for treating leukemia and food processing. [ABSTRACT FROM AUTHOR]

L-asparaginase was screened for during the current study in several Caryota urens plant sections. One possible source for L-asparaginase synthesis was identified as the unripe fruit with the highest enzyme activity (925U/ml). The discovery of L-asparaginase in Caryota urens is a first. The enzyme was 38% pure, with an 85-fold purification factor, and 3325U/ml of total enzyme activity after purification. It was discovered that the enzyme's kinetic parameters, Km and Vmax, were 13.8 mM and 100µM/ml, respectively. The partly purified enzyme was shown to be a single protein with a molecular weight of 47 kDa by SDS-PAGE electrophoresis. The cytotoxic effects of L-asparaginase against the K562 and PBMC (peripheral blood mononuclear cell) cell line were investigated; the results showed 26% and 96% (IC50 23.03µg/ml) of cytotoxicity, respectively. Future research can examine the effectiveness of L-asparaginase from Caryota urens L., as it exhibits little glutaminase activity and reduced toxicity toward PBMC. [ABSTRACT FROM AUTHOR]

Cervical cancer is caused by a persistent and high-grade infection. It is caused by the Human Papillomavirus (HPV), which, when entering cervical cells, alters their physiology and generates serious lesions. HPV 18 is among those most involved in carcinogenesis in this region, but there are still no drug treatments that cause cure or total remission of lesions caused by HPV. It is known that L-asparaginase is an amidohydrolase, which plays a significant role in the pharmaceutical industry, particularly in the treatment of specific cancers. Due to its antitumor properties, some studies have demonstrated its cytotoxic effect against cervical cancer cells. However, the commercial version of this enzyme has side effects, such as hypersensitivity, allergic reactions, and silent inactivation due to the formation of antibodies. To mitigate these adverse effects, several alternatives have been explored, including the use of L-asparaginase from other microbiological sources, which is the case with the use of the fungus Aspergillus niger, a high producer of L-asparaginase. The study investigated the influence of the type of fermentation, precipitant, purification, characterization, and in vitro cytotoxicity of L-asparaginase. The results revealed that semisolid fermentation produced higher enzymatic activity and protein concentration of A. niger. The characterized enzyme showed excellent stability at pH 9.0, temperature of 50 °C, resistance to surfactants and metallic ions, and an increase in enzymatic activity with the organic solvent ethanol. Furthermore, it exhibited low cytotoxicity in GM and RAW cells and significant cytotoxicity in HeLa cells. These findings indicate that L-asparaginase derived from A. niger may be a promising alternative for pharmaceutical production. Its attributes, including stability, activity, and low toxicity in healthy cells, suggest that this modified enzyme could overcome challenges associated with antitumor therapy. [ABSTRACT FROM AUTHOR]

ReAV, the inducible Class-3 L-asparaginase from the nitrogen-fixing symbiotic bacterium Rhizobium etli, is an interesting candidate for optimizing its enzymatic potential for antileukemic applications. Since it has no structural similarity to known enzymes with this activity, it may offer completely new ways of approach. Also, as an unrelated protein, it would evade the immunological response elicited by other asparaginases. The crystal structure of ReAV revealed a uniquely assembled protein homodimer with a highly specific C135/K138/C189 zinc binding site in each subunit. It was also shown before that the Zn2+ cation at low and optimal concentration boosts the ReAV activity and improves substrate specificity, which indicates its role in substrate recognition. However, the detailed catalytic mechanism of ReAV is still unknown. In this work, we have applied site-directed mutagenesis coupled with enzymatic assays and X-ray structural analysis to elucidate the role of the residues in the zinc coordination sphere in catalysis. Almost all of the seven ReAV muteins created in this campaign lost the ability to hydrolyze L-asparagine, confirming our predictions about the significance of the selected residues in substrate hydrolysis. We were able to crystallize five of the ReAV mutants and solve their crystal structures, revealing some intriguing changes in the active site area as a result of the mutations. With alanine substitutions of Cys135 or Cys189, the zinc coordination site fell apart and the mutants were unable to bind the Zn2+ cation. Moreover, the absence of Lys138 induced atomic shifts and conformational changes of the neighboring residues from two active-site Ser-Lys tandems. Ser48 from one of the tandems, which is hypothesized to be the catalytic nucleophile, usually changes its hydration pattern in response to the mutations. Taken together, the results provide many useful clues about the catalytic mechanism of the enzyme, allowing one to cautiously postulate a possible enzymatic scenario. [ABSTRACT FROM AUTHOR]

This study investigated the effect of polycationic and uncharged polymers (and oligomers) on the catalytic parameters and thermostability of L-asparaginase from Thermococcus sibiricus (TsA). This enzyme has potential applications in the food industry to decrease the formation of carcinogenic acrylamide during the processing of carbohydrate-containing products. Conjugation with the polyamines polyethylenimine and spermine (PEI and Spm) or polyethylene glycol (PEG) did not significantly affect the secondary structure of the enzyme. PEG contributes to the stabilization of the dimeric form of TsA, as shown by HPLC. Furthermore, neither polyamines nor PEG significantly affected the binding of the L-Asn substrate to TsA. The conjugates showed greater maximum activity at pH 7.5 and 85 °C, 10–50% more than for native TsA. The pH optima for both TsA-PEI and TsA-Spm conjugates were shifted to lower pH ranges from pH 10 (for the native enzyme) to pH 8.0. Additionally, the TsA-Spm conjugate exhibited the highest activity at pH 6.5–9.0 among all the samples. Furthermore, the temperature optimum for activity at pH 7.5 shifted from 90–95 °C to 80–85 °C for the conjugates. The thermal inactivation mechanism of TsA-PEG appeared to change, and no aggregation was observed in contrast to that of the native enzyme. This was visually confirmed and supported by the analysis of the CD spectra, which remained almost unchanged after heating the conjugate solution. These results suggest that TsA-PEG may be a more stable form of TsA, making it a potentially more suitable option for industrial use. [ABSTRACT FROM AUTHOR]

Acrylamide (AA) is a toxic substance formed in many carbohydrate-rich food products, whose formation can be reduced by adding some additives. Furthermore, the type of food consumed determines the AA intake. According to the compiled information, the first route causing AA formation is the Maillard reaction. Some interventions, such as reducing AA precursors in raw materials, (i.e., asparagine), reducing sugars, or decreasing temperature and processing time can be applied to limit AA formation in food products. The L-asparaginase is more widely used in potato products. Also, coatings loaded with proteins, enzymes, and phenolic compounds are new techniques for reducing AA content. Enzymes have a reducing effect on AA formation by acting on asparagine; proteins by competing with amino acids to participate in Maillard, and phenolic compounds through their radical scavenging activity. On the other hand, some synthetic and natural additives increase the formation of AA. Due to the high exposure to AA and its toxic effects, it is essential to recognize suitable food additives to reduce the health risks for consumers. In this sense, this study focuses on different additives that are proven to be effective in the reduction or formation of AA in food products. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Thermostability is an important and desired feature of therapeutic proteins and is critical for the success or failure of protein drugs development. It can be increased by PEGylation—binding of poly(ethylene glycol) moieties—or glycosylation—post-translational modification to add glycans. Here, the thermostability and thermodynamic parameters of native, PEGylated, and glycosylated versions of the antileukemic enzyme crisantaspase were investigated. First-order kinetics was found to describe the irreversible deactivation process. Activation energy of the enzyme-catalyzed reaction (E*) was estimated for native, PEGylated, and glycosylated enzyme (10.2, 14.8, and 18.8 kJ mol−1 respectively). Half-life decreased progressively with increasing temperature, and longer half-life was observed for PEG-crisantaspase (87.74 min) at 50 °C compared to the native form (9.79 min). The activation energy of denaturation of PEG-crisantaspase (307.1 kJ mol−1) was higher than for crisantaspase (218.1 kJ mol−1) and Glyco-crisantaspase (120.0 kJ mol−1), which means that more energy is required to overcome the energy barrier of the unfolding process. According to our results, PEG-crisantaspase is more thermostable than its native form, while Glyco-crisantaspase is more thermosensitive. [ABSTRACT FROM AUTHOR]

In recent years, the need for L-asparaginase in different industries has increased. L-asparaginase obtained from microorganisms is cost-effective, has no harmful effects on the environment, and improves the quality of products. In the present study, L-asparaginase-producing microorganisms were isolated and optimized from different sources, and selected strain enzymes were produced. L-asparaginase-producing yeasts were randomly isolated and purified from different parts of Isfahan. Strains were screened for L-asparaginase production. Then, the superior yeast strain with the highest enzymatic activity was selected for optimization. Under suitable pH, temperature, time, carbon source, and nitrogen source, multi-factor optimization was performed using response-level statistical software to investigate the simultaneous effect of several factors on production and the highest enzyme activity. In the present study, 5S2 yeast isolate led to the formation of the highest halo of L-asparaginase. This strain was first introduced as the L-asparaginase-producing strain and was registered in the NCBI database under Diutina mesorugosa strain SBG-IAUF-2 with access number MZ901211. Yeast 5S2 with enzyme activity equivalent to 1722.8 u / ml was selected as the selected strain for optimization. The results of multivariate optimization of enzyme activity showed that at pH 7, a concentration of 2% glucose as carbon source, the attention of 10% L-asparagine, a temperature of 35°C, and a time of 120 hours, there is the highest enzyme production activity and curve RSM is located in the optimization area. In the present study, after recording 5S2 yeast isolate for the first time as an L-asparaginaseproducing strain in the NCBI database, extracellular L-asparaginase produced by the 5S2 yeast strain was introduced due to its high enzymatic activity as a potent strain in the production of Lasparaginase enzyme. [ABSTRACT FROM AUTHOR]

Background: l-Asparaginase is a crucial component of acute lymphoblastic leukemia (ALL) treatment. However, hypersensitivity is a common adverse event. This study aimed to identify risk factors for l-asparaginase hypersensitivity in childhood ALL. Methods: Children treated for ALL at Chiang Mai University Hospital, Thailand, between 2005 and 2020 were included. Demographic data, clinical characteristics, and factors related to l-asparaginase were retrospectively reviewed. Results: l-Asparaginase hypersensitivity was observed in 24 of 216 children with ALL (11.1%). All patients received native l-asparaginase intramuscularly, and events occurred exclusively during the post-induction phase without concurrent corticosteroid use. Univariable analysis showed that relapsed ALL, higher accumulated doses, increased exposure days, and longer interval between drug administrations were potential risk factors. In multivariable logistic regression analysis, interruption of l-asparaginase administration for ≥ 52 weeks and exposure duration of ≥ 15 days were independent risk factors, with adjusted odds ratio of 16.481 (95% CI 3.248–83.617, p = 0.001) and 4.919 (95% CI 1.138–21.263, p = 0.033), respectively. Conclusions: Children with ALL who require re-exposure to l-asparaginase after 52-week interruption or who have received l-asparaginase for ≥ 15 exposure days are at risk of developing l-asparaginase hypersensitivity. Further management strategies in this setting should be evaluated. [ABSTRACT FROM AUTHOR]

Silent inactivation of L-asparaginase (L-Asp) represents rapid clearance of L-Asp by anti-L-Asp IgG antibodies without clinical symptoms. Measurement of L-Asp activity is the gold standard for diagnosis of silent inactivation, but this test is not commercially available in Japan as of 2023. We evaluated ex vivo and in vivo ammonia production in relation to L-Asp activity. Blood samples from ten adult patients treated with L-Asp were collected to measure ammonia levels and L-Asp activity before the first dose and 24 h after the last dose of L-Asp, during each cycle of treatment. Plasma ammonia levels were analyzed immediately and 1 h after incubation at room temperature, and ex vivo ammonia production was defined as the increase in ammonia concentration. Ex vivo ammonia production correlated with L-Asp activity (R2 = 0.741), and ammonia levels measured immediately after blood collection were moderately correlated with L-Asp activity (R2 = 0.709). One patient with extranodal NK/T-cell lymphoma showed an increase in ammonia levels during the first cycle, but no increase in ammonia levels or L-Asp activity after L-Asp administration during the second cycle. Both ex vivo and in vivo ammonia production and surrogate markers are used for L-Asp biological activity. [ABSTRACT FROM AUTHOR]

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Background: Thromboembolic complications are well known in the treatment of childhood acute lymphoblastic leukemia. Over the years it has not been possible to reach a consensus on a possible prophylaxis of thromboembolic events during intensive therapy. Only the administration of enoxaparin was able to achieve evidence in the literature to date. Methods: In this retrospective study, 173 childhood leukemia patients were treated over 20 years with a thromboembolic prophylaxis including enoxaparin and AT III during induction therapy with L-asparaginase and cortisone. Results: We here report the effectiveness of administration of enoxaparin and AT III in childhood leukemia, showing a strikingly low prevalence of deep vein thrombosis (2.9%). Especially in adolescent patients, a particularly great need for AT III was demonstrated. Conclusions: We recommend thromboembolic prophylaxis with enoxaparin and AT III substitution during induction/reinduction therapy with L-asparaginase and glucocorticosteroids, especially from adolescence onwards. [ABSTRACT FROM AUTHOR]

A dataset comprising metagenomes of outpatients (n = 28) with acute leukemia (AL) and healthy controls (n = 14) was analysed to investigate the associations between gut microbiota composition and metabolic activity and AL. According to the results obtained, no significant differences in the microbial diversity between AL outpatients and healthy controls were found. However, significant differences in the abundance of specific microbial clades of healthy controls and AL outpatients were found. We found some differences at taxa level. The relative abundance of Enterobacteriaceae, Prevotellaceae and Rikenellaceae was increased in AL outpatients, while Bacteirodaceae, Bifidobacteriaceae and Lachnospiraceae was decreased. Interestingly, the abundances of several taxa including Bacteroides and Faecalibacterium species showed variations based on recovery time from the last cycle of chemotherapy. Functional annotation of metagenome-assembled genomes (MAGs) revealed the presence of functional domains corresponding to therapeutic enzymes including l-asparaginase in a wide range of genera including Prevotella, Ruminococcus, Faecalibacterium, Alistipes, Akkermansia. Metabolic network modelling revealed potential symbiotic relationships between Veillonella parvula and Levyella massiliensis and several species found in the microbiota of AL outpatients. These results may contribute to develop strategies for the recovery of microbiota composition profiles in the treatment of patients with AL. [ABSTRACT FROM AUTHOR]

This study reports the antioxidant potential and L-asparaginase production of culturable fungal endophytes from Dendrobium orchids in Malaysia. Twenty-nine isolates were screened using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay to determine their free radical scavenging activities and antioxidant capacity (IC50 and AEAC). L-asparaginase production of fungal endophytes was detected by the qualitative plate assay, and the enzyme activities estimated via the Nesslerization method. All 29 endophytic isolates exhibited various degrees of radical scavenging activities (35.37%–77.23%), with Fusarium fujikuroi (D1) identified as having the highest antioxidant capacity (IC50 6.097 mg/mL) and the highest AEAC value (11.55  mg/g). For L-asparaginase production, the majority of the isolates (89.66%) showed positive results, especially among the culturable species of Fusarium, Trichoderma , and Daldinia. Most Fusarium spp. were able to produce L-asparaginase (80.77%), but the highest L-asparaginase activity was detected in Daldinia eschscholtzii (D14) with 2.128 units/mL. Results from this study highlighted the potential of endophytic fungi from medicinal orchids (Dendrobium sp.) as natural sources of bioactive compounds to be developed into novel antioxidants and anticancer drugs. [ABSTRACT FROM AUTHOR]