Bioprospecting of the agaricomycete Ganoderma australe GPC191 as novel source for L-asparaginase production

Desirable L-asparaginases for treating cancer and current research trends

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

In vitro and in silico analysis unravelled clinically desirable attributes of Bacillus altitudinis L-asparaginase

AIMS

To identify a marine L-asparaginase with clinically desirable attributes and characterize the shortlisted candidate through in silico tools.

METHODS AND RESULTS

Marine bacterial strains (number = 105) isolated from marine crabs were evaluated through a stepwise strategy incorporating the crucial attributes for therapeutic safety. The results demonstrated the potential of eight bacterial species for extracellular L-asparaginase production. However, only one isolate (Bacillus altitudinis CMFRI/Bal-2) showed clinically desirable attributes, viz. extracellular production, type-II nature, lack of concurrent L-glutaminase and urease activities, and presence of ansZ (functional gene for clinical type). The enzyme production was 22.55 ± 0.5 µM/mg protein/min within 24 h without optimization. The enzyme also showed good activity and stability in pH 7-8 and temperature 37°C, predicting the functioning inside the human body. The Michealis-Menten constant (Km) was 14.75 µM. Detailed in silico analysis based on functional gene authenticating the results of in vitro characterization and predicted the nonallergenic characteristic of the candidate. Docking results proved the higher affinity of the shortlisted candidate to L-asparagine than L-glutamine and urea.

CONCLUSION

Comprehensively, the study highlighted B. altitudinis type II asparaginase as a competent candidate for further research on clinically safe asparaginases.

Application of sequential design for enhanced L-asparaginase synthesis from Ganoderma australe GPC191

With an increasing demand for L-asparaginase in pharmaceutical and food sectors for its cytostatic and acrylamide-reducing qualities, there's a need to discover novel, highly productive enzyme sources with improved pharmacokinetic profiles. Keeping this in mind, the present study aimed at maximizing the potential of Ganoderma australe GPC191 to produce L-asparaginase by fermentation medium optimization using statistical validation. Of the 11 physicochemical parameters evaluated under submerged fermentation conditions through one-factor-at-a-time approach and Plackett-Burman design, only four parameters (inoculum load, L-asparagine, soybean meal, and initial pH) influenced L-asparaginase production, significantly (p < 0.001). The optimal levels and interaction effects of these on the overall production were further evaluated by the central composite rotatable design of response surface methodology. Post-optimization, 27.34 U/mL was predicted as the maximum activity at pH 7 with 5n inoculum load and 15 g/L each of L-asparagine and soybean meal. Experimental validation yielded an activity of 28.52 U/mL, indicating an overall 18.17-fold increase from the unoptimized stage. To our knowledge, this is the first report signifying the L-asparaginase production aptitude of G. australe with sequential statistical validation using agricultural waste, which can serve as a model to enhance its yields, offering a sustainable and cost-effective solution for industrial application.

The colorful world of sulfonephthaleins: Current applications in analytical chemistry for "old but gold" molecules

Sulfonephthaleins represent one of the most common and widely employed reactive dyes in analytical chemistry, thanks to their stability, low-cost, well-visible colors, reactivity and possibilities of chemical modification. Despite being first proposed in 1916, nowadays, these molecules play a fundamental role in biological and medical applications, environmental analyses, food quality monitoring and other fields, with a particular focus on low-cost and disposable devices or methods for practical applications. Since up to our knowledge, no reviews or book chapters focused explicitly on sulfonephthaleins have ever been published, in this review, we will briefly describe sulfonephthaleins history, their acid-base properties will be discussed, and the most recent applications in different fields will be presented, focusing on the last ten years literature (2014-2023). Finally, safety and environmental issues will be briefly discussed, despite being quite controversial.

Endophytic Fungi as a Promising Source of Anticancer L-Asparaginase: A Review

L-asparaginase is a tetrameric enzyme from the amidohydrolases family, that catalyzes the breakdown of L-asparagine into L-aspartic acid and ammonia. Since its discovery as an anticancer drug, it is used as one of the prime chemotherapeutic agents to treat acute lymphoblastic leukemia. Apart from its use in the biopharmaceutical industry, it is also used to reduce the formation of a carcinogenic substance called acrylamide in fried, baked, and roasted foods. L-asparaginase is derived from many organisms including plants, bacteria, fungi, and actinomycetes. Currently, L-asparaginase preparations from Escherichia coli and Erwinia chrysanthemi are used in the clinical treatment of acute lymphoblastic leukemia. However, they are associated with low yield and immunogenicity problems. At this juncture, endophytic fungi from medicinal plants have gained much attention as they have several advantages over the available bacterial preparations. Many medicinal plants have been screened for L-asparaginase producing endophytic fungi and several studies have reported potent L-asparaginase producing strains. This review provides insights into fungal endophytes from medicinal plants and their significance as probable alternatives for bacterial L-asparaginase.

Thermostability enhancement and insight of L-asparaginase from Mycobacterium sp. via consensus-guided engineering

Acrylamide alleviation in food has represented as a critical issue due to its neurotoxic effect on human health. L-Asparaginase (ASNase, EC 3.5.1.1) is considered a potential additive for acrylamide alleviation in food. However, low thermal stability hinders the application of ASNase in thermal food processing. To obtain highly thermal stable ASNase for its industrial application, a consensus-guided approach combined with site-directed saturation mutation (SSM) was firstly reported to engineer the thermostability of Mycobacterium gordonae L-asparaginase (GmASNase). The key residues Gly97, Asn159, and Glu249 were identified for improving thermostability. The combinatorial triple mutant G97T/N159Y/E249Q (TYQ) displayed significantly superior thermostability with half-life values of 61.65 ± 8.69 min at 50 °C and 5.12 ± 1.66 min at 55 °C, whereas the wild-type was completely inactive at these conditions. Moreover, its T_m value increased by 8.59 °C from parent wild-type. Interestingly, TYQ still maintained excellent catalytic efficiency and specific activity. Further molecular dynamics and structure analysis revealed that the additional hydrogen bonds, increased hydrophobic interactions, and favorable electrostatic potential were essential for TYQ being in a more rigid state for thermostability enhancement. These results suggested that our strategy was an efficient engineering approach for improving fundamental properties of GmASNase and offering GmASNase as a potential agent for efficient acrylamide mitigation in food industry. KEY POINTS: • The thermostability of GmASNase was firstly improved by consensus-guided engineering. • The half-life and T_m value of triple mutant TYQ were significantly increased. • Insight on improved thermostability of TYQ was revealed by MD and structure analysis.

Characterization of a novel and glutaminase-free type II L-asparaginase from Corynebacterium glutamicum and its acrylamide alleviation efficiency in potato chips

Type II L-asparaginase as a pivotal enzyme agent has been applied to treating for acute lymphoblastic leukemia (ALL) and efficient mitigation of acrylamide formed in fried and baked foods. However, low activity, narrow range of pH stability, as well as undesirable glutaminase activity hinder the applications of this enzyme. In our work, A novel type II L-asparaginase (CgASNase) from Corynebacterium glutamicum with molecular mass of about 35 kDa was chosen to express in E. coli. CgASNase shared only 27 % structural identity with the reported L-asparaginase from Helicobacter pylori. The purified CgASNase showed the highest specific activity of 1979.08 IU mg^-1 to L-asparagine, compared with reported type II ASNases in the literature. CgASNase displayed superior stability at a wide pH range from 5.0 to 11.0, and retained about 76 % of its activity at 30 °C for 30 min. The kinetic parameters K_m (Michaelis constant), k_cat (turnover number), and k_cat/K_m (catalytic efficiency) values of 4.66 mM, 79,697.40 min^-1, and 17,102.45 mM^-1 min^-1, respectively. More importantly, CgASNase exhibited strict substrate specificity towards L-asparagine, no detectable activity to l-glutamine. To explore its ability to catalyze L-asparagine, CgASNase was supplied in frying potato chips, which produced the fries with 84 % less acrylamide content compared with no supply. These findings suggest that CgASNase presents excellent properties for chemotherapy against diseases and great potential in the food processing industry.

Improved Foods Using Enzymes from Basidiomycetes

Within the kingdom of fungi, the division Basidiomycota represents more than 30,000 species, some with huge genomes indicating great metabolic potential. The fruiting bodies of many basidiomycetes are appreciated as food (“mushrooms”). Solid-state and submerged cultivation processes have been established for many species. Specifically, xylophilic fungi secrete numerous enzymes but also form smaller metabolites along unique pathways; both groups of compounds may be of interest to the food processing industry. To stimulate further research and not aim at comprehensiveness in the broad field, this review describes some recent progress in fermentation processes and the knowledge of fungal genetics. Processes with potential for food applications based on lipases, esterases, glycosidases, peptidases and oxidoreductases are presented. The formation and degradation of colourants, the degradation of harmful food components, the formation of food ingredients and particularly of volatile and non-volatile flavours serve as examples. In summary, edible basidiomycetes are foods—and catalysts—for food applications and rich donors of genes to construct heterologous cell factories for fermentation processes. Options arise to support the worldwide trend toward greener, more eco-friendly and sustainable processes.

Overview of the structure, side effects, and activity assays of l-asparaginase as a therapy drug of acute lymphoblastic leukemia

l-Asparaginase (l-ASNase is the abbreviation, l-asparagine aminohydrolase, E.C.3.5.1.1) is an enzyme that is clinically employed as an antitumor agent for the treatment of acute lymphoblastic leukemia (ALL). Although l-ASNase is known to deplete l-asparagine (l-Asn), causing cytotoxicity in leukemia cells, the specific molecular signaling pathways are not well defined. Because of the deficiencies in the production and administration of current formulations, the l-ASNase agent in clinical use is still associated with serious side effects, so controlling its dose and activity monitoring during therapy is crucial for improving the treatment success rate. Accordingly, it is urgent to summarize and develop effective analytical methods to detect l-ASNase activity in treatment. However, current reports on these detection methods are fragmented and also have not been systematically summarized and classified, thereby not only delaying the investigations of specific molecular mechanisms, but also hindering the development of novel detection methods. Herein, in this review, we provided a detailed summary of the l-ASNase structures, antitumor mechanism and side effects, and current detection approaches, such as fluorescence assays, colorimetric assays, spectroscopic assays and some other assays. All of them possess unique advantages and disadvantages, so it has been difficult to establish clear criteria for clinical application. We hope that this review will be of some value in promoting the development of l-ASNase activity detection methods.

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

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