Biochemical characterization and immobilization of Erwinia carotovora l -asparaginase in a microplate for high-throughput biosensing of l -asparagine

L-asparaginase-mediated pH shift and carbon dot fluorescence modulation: A sensitive ratiometric method for quantifying L-asparagine in diverse potato varieties under variable storage conditions

This study presents a novel and selective method for the determination of l-asparagine in diverse potato varieties under various storage conditions. L-asparagine levels serve as a crucial indicator for acrylamide formation, a hazardous substance in processed potato products. The fluorometric method utilized blue-emitting CDs (B-CDs), orange-emitting CDs (O-CDs), and the enzyme L-asparaginase for ratiometric detection of L-asparagine. Upon enzymatic hydrolysis of L-asparagine by L-asparaginase, liberated ammonia induced a pH increase in the reaction medium. This pH shift enhanced the fluorescence of B-CDs while simultaneously decreasing that of O-CDs, enabling sensitive and selective L-asparagine quantification. Comprehensive characterization of the CDs was performed using various spectroscopic techniques and transmission electron microscopy. The method demonstrated excellent sensitivity (LOD = 0.31 μM) and a wide linear range (1.0-50.0 μM). When the method was applied to potato samples, high recovery values (98.00-100.33 %) with low relative standard deviations (RSDs) were achieved, confirming the accuracy and precision of the method. The approach was employed to determine L-asparagine levels in three potato varieties (Lady Rosetta, Spunta, and Nicola) under different storage temperatures and durations. This method provides a valuable tool for monitoring L-asparagine content in potatoes, potentially aiding in the mitigation of acrylamide formation during processing. The robust performance and simplicity of the proposed technique make it suitable for routine analysis in both research and industrial applications within the potato industry.

A systematic review of recent trends in research on therapeutically significant L-asparaginase and acute lymphoblastic leukemia

L-asparaginases are mostly obtained from bacterial sources for their application in the therapy and food industry. Bacterial L-asparaginases are employed in the treatment of Acute Lymphoblastic Leukemia (ALL) and its subtypes, a type of blood and bone marrow cancer that results in the overproduction of immature blood cells. It also plays a role in the food industry in reducing the acrylamide formed during baking, roasting, and frying starchy foods. This importance of the enzyme makes it to be of constant interest to the researchers to isolate novel sources. Presently L-asparaginases from E. coli native and PEGylated form, Dickeya chrysanthemi (Erwinia chrysanthemi) are in the treatment regime. In therapy, the intrinsic glutaminase activity of the enzyme is a major drawback as the patients in treatment experience side effects like fever, skin rashes, anaphylaxis, pancreatitis, steatosis in the liver, and many complications. Its significance in the food industry in mitigating acrylamide is also a major reason. Acrylamide, a potent carcinogen was formed when treating starchy foods at higher temperatures. Acrylamide content in food was analyzed and pre-treatment was considered a valuable option. Immobilization of the enzyme is an advancing and promising technique in the effective delivery of the enzyme than in free form. The concept of machine learning by employing the Artificial Network and Genetic Algorithm has paved the way to optimize the production of L-asparaginase from its sources. Gene-editing tools are gaining momentum in the study of several diseases and this review focuses on the CRISPR-Cas9 gene-editing tool in ALL.

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

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

Supplementary Information

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

An Integrative, Multiparametric Approach for the Comprehensive Assessment of Microbial Quality and Pollution in Aquaculture Systems

As the aquaculture sector significantly expanded worldwide in the past decades, the concept of sustainable aquaculture has developed with the challenge of not only maximizing benefits but also minimizing the negative impacts on the environment assuring, at the same time, food security. In this framework, monitoring and improving the microbiological water quality and animal health are a central topic. In the present study, we evaluated the seawater microbiological quality in a mariculture system located in a Mediterranean coastal area (Northern Ionian Sea, Italy). We furnished, for the first time, a microbial inventory based on conventional culture-based methods, integrated with the 16S rRNA gene metabarcoding approach for vibrios identification and diversity analyses, and further implemented with microbial metabolic profiling data obtained from the Biolog EcoPlate system. Microbiological pollution indicators, vibrios diversity, and microbial metabolism were determined in two different times of the year (July and December). All microbial parameters measured in July were markedly increased compared to those measured in December. The presence of potentially pathogenic vibrios is discussed concerning the risk of fish disease and human infections. Thus, the microbial inventory here proposed might represent a new multiparametric approach for the suitable surveillance of the microbial quality in a mariculture system. Consequently, it could be useful for ensuring the safety of both the reared species and the consumers in the light of sustainable, eco-friendly aquaculture management.

Bio-fabrication of thermozyme-based nano-biosensors: their components and present scenario

An amalgamation of microbiology, biocatalysis, recombinant molecular biology, and nanotechnology is crucial for groundbreaking innovation in developing nano-biomedicines and sensoristics. Enzyme-based nano-biosensor finds prospective applications in various sectors (environmental, pharmaceutical, food, biorefineries). These applications demand reliable catalytic efficiency and functionality of the enzyme under an extreme operational environment for a prolonged period. Over the last few years, bio-fabrication of nano-biosensors in conjunction with thermozymes from thermophilic microbes is being sought after as a viable design. Thermozymes are known for their robustness, are chemically resistant toward organic solvents, possess higher durability for constant use, catalytic ability, and stability at elevated temperatures. Additionally, several other attributes of thermozymes like substrate specificity, selectivity, and sensitivity make them desirable in developing a customized biosensor. In this review, crucial designing aspects of enzyme-based nano-biosensors like enzyme immobilization on an electrode surface, new materials derived from microbial sources (biopolymers based nanocomposites), improvisation measures for sensitivity, and selectivity have been addressed. It also covers microbial biosynthesis of nanomaterials used to develop sensoristic devices and its numerous applications such as wastewater treatment, biorefineries, and diagnostics. The knowledge will pave the way toward creating consistent eco-friendly, economically viable nanostructured-based technologies with broad applicability and exploitation for industrial use in the near future.

Development of Processes for Recombinant L-Asparaginase II Production by Escherichia coli Bl21 (De3): From Shaker to Bioreactors

Since 1961, L-asparaginase has been used to treat patients with acute lymphocytic leukemia. It rapidly depletes the plasma asparagine and deprives the blood cells of this circulating amino acid, essential for the metabolic cycles of cells. In the search for viable alternatives to produce L-asparaginase, this work aimed to produce this enzyme from Escherichia coli in a shaker and in a 3 L bioreactor. Three culture media were tested: defined, semi-defined and complex medium. L-asparaginase activity was quantified using the β-hydroxamate aspartic acid method. The defined medium provided the highest L-asparaginase activity. In induction studies, two inducers, lactose and its analog IPTG, were compared. Lactose was chosen as an inducer for the experiments conducted in the bioreactor due to its natural source, lower cost and lower toxicity. Batch and fed-batch cultures were carried out to reach high cell density and then start the induction. Batch cultivation provided a final cell concentration of 11 g L-1 and fed-batch cultivation produced 69.90 g L-1 of cells, which produced a volumetric activity of 43,954.79 U L-1 after lactose induction. L-asparaginase was produced in a shaker and scaled up to a bioreactor, increasing 23-fold the cell concentration and thus, the enzyme productivity.

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.

Constitutive expression of Asparaginase in Gossypium hirsutum triggers insecticidal activity against Bemisia tabaci

Whitefly infestation of cotton crop imparts enormous damage to cotton yield by severely affecting plant health, vigour and transmitting Cotton Leaf Curl Virus (CLCuV). Genetic modification of cotton helps to overcome both the direct whitefly infestation as well as CLCuV based cotton yield losses. We have constitutively overexpressed asparaginase (ZmASN) gene in Gossypium hirsutum to overcome the cotton yield losses imparted by whitefly infestation. We achieved 2.54% transformation efficiency in CIM-482 by Agrobacterium-mediated shoot apex transformation method. The relative qRT-PCR revealed 40-fold higher transcripts of asparaginase in transgenic cotton line vs. non-transgenic cotton lines. Metabolic analysis showed higher contents of aspartic acid and glutamic acid in seeds and phloem sap of the transgenic cotton lines. Phenotypically, the transgenic cotton lines showed vigorous growth and height, greater number of bolls, and yield. Among six representative transgenic cotton lines, line 14 had higher photosynthetic rate, stomatal conductance, smooth fiber surface, increased fiber convolutions (SEM analysis) and 95% whitefly mortality as compared to non-transgenic cotton line. The gene integration analysis by fluorescence in situ hybridization showed single copy gene integration at chromosome number 1. Collectively, asparaginase gene demonstrated potential to control whitefly infestation, post-infestation damages and improve cotton plant health and yield: a pre-requisite for farmer's community.

A Surface Acoustic Wave (SAW) biosensor method for functional quantification of E. colil-asparaginase

Biosensors are rising technologies in the pharmaceutical field for medicine discovery, development and Quality Control (QC) stages. Surface acoustic wave (SAW) biosensor employs acoustic waves generated by oscillating a piezoelectric crystal quartz plate to meas. mass and viscosity, and allows to detect and quantify binding events between the analyte and an immobilized interacting ligand. We present here a SAW biosensor based approach for the functional quantification of Escherichia colil-asparaginase (E. colil-ASNase), using polyclonal antibody (pAb) as the interaction partner immobilized on the chip. Different immobilization strategies of pAb were initially evaluated, resulting in the BS³ activated amide coupling via protein G strategy as the final immobilization method. The method was validated by evaluating the selectivity, linearity, as well as accuracy (a recovery of 102.4%) and precision (RSD of 8.5%). The application of the validated method on different samples encompassing different lots of E. colil-ASNase, deamidated E. colil-ASNase and dry-heated E. colil-ASNase (80 °C, 10 min) indicated the suitability of the developed SAW method to quantify E. colil-ASNase. We suggest this SAW method can be adopted as a pharmaceutical QC method.

Marine microbial L-asparaginase: Biochemistry, molecular approaches and applications in tumor therapy and in food industry

The marine environment is a rich source of biological and chemical diversity. It covers more than 70% of the Earth's surface and features a wide diversity of habitats, often displaying extreme conditions, where marine organisms thrive, offering a vast pool for microorganisms and enzymes. Given the dissimilarity between marine and terrestrial habitats, enzymes and microorganisms, either novel or with different and appealing features as compared to terrestrial counterparts, may be identified and isolated. L-asparaginase (E.C. 3.5.1.1), is among the relevant enzymes that can be obtained from marine sources. This amidohydrolase acts on L-asparagine and produce L-aspartate and ammonia, accordingly it has an acknowledged chemotherapeutic application, namely in acute lymphoblastic leukemia. Moreover, L-asparaginase is also of interest in the food industry as it prevents acrylamide formation. Terrestrial organisms have been largely tapped for L-asparaginases, but most failed to comply with criteria for practical applications, whereas marine sources have only been marginally screened. This work provides an overview on the relevant features of this enzyme and the framework for its application, with a clear emphasis on the use of L-asparaginase from marine sources. The review envisages to highlight the unique properties of marine L-asparaginases that could make them good candidates for medical applications and industries, especially in food safety.

Ratiometric fluorescent l-arginine and l-asparagine biosensors based on the oxazine 170 perchlorate-ethyl cellulose membrane

Ratiometric fluorescent l-arginine (Arg) and l-asparagine (Asn) biosensors were developed using an oxazine 170 perchlorate (O17) ethyl cellulose (EC) membrane and the enzymes entrapped into the matrix of EC and hydrogel polyurethane. The sensing principles were based on the hydrolysis reactions of urea and l-Arg under the catalysis of the urease and arginase to produce ammonia in the case of an l-Arg-sensing membrane and also on the hydrolysis reaction of l-Asn under the catalysis of asparaginase in the case of an l-Asn-sensing membrane. The O17-EC membrane reacted with the ammonia produced from the hydrolysis reactions and changed the fluorescence intensities at λ _em = 565 and 625 nm. The ratio of the fluorescence intensities at λ _em = 565 and 625 nm was proportional to the concentrations of l-Arg or l-Asn in the range of 0.1-10 mM. The LOD of the l-Arg- and l-Asn-sensing membranes was 0.082 ± 0.0014 and 0.074 ± 0.0023 mM, respectively. The sensing membranes also showed good quality in terms of response time, reversibility, and stability. The interference study demonstrated that some components such as amino acids had little negative effects on the performance of the sensing membranes for the detection of l-Arg and l-Asn. These simple and sensitive ratiometric fluorescent sensing membranes provide a basic or comprehensive method for detecting l-Arg and l-Asn in blood and urine samples as well as in the fermentation processes.