Effect of osmolytes on the activity of anti-cancer enzyme L-Asparaginase II from Erwinia chrysanthemi

Substrate Affinity Is Not Crucial for Therapeutic L-Asparaginases: Antileukemic Activity of Novel Bacterial Enzymes

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.

Stable and effective eco-enzyme cocktails in powder and liquid form of Stachybotrys microspora used as detergent additives

Objective

The present work aims to optimize fermentation parameters for the simultaneous production of eco-enzymes: proteases, amylases, and endoglucanases from the same fungus Stachybotrys microspora, and to evaluate their stability in free form and formulated in lye as detergent additives.

Methods

Initially, enzyme cocktail production was assayed in a medium comprising inexpensive waste biomass. Using the best substrate, we investigated the effect of its different concentrations and the NaCl concentration on the three enzymes co-production. Next, we studied the effect of several additives on the storage stability of the lyophilized enzyme cocktail (powder in liquid forms) free and incorporated in commercial laundry detergent. Finally, the washing efficiency analysis of the newly formulated enzyme cocktail was evaluated on dirty tissue pieces with different stains.

Results

The highest enzymatic cocktail production was achieved at 30 °C for 96 h after adding 0.1% NaCl and 1.5% wheat bran as waste biomass in the basal culture medium. The effect of adding maltodextrin, sucrose, or polyethylene glycol 4000 during freeze-drying showed that maltodextrin is the best additive to protect the activities of proteases, amylases, and cellulases of liquid and powder enzyme form. Additionally, the liquid formulation of these enzymes showed excellent stability and compatibility with 1% maltodextrin and 10% glycerol. Interestingly, we have developed a new formulation of an enzyme cocktail (liquid and powder) stable and highly compatible with detergents. Comparing the washing performance of different formulations containing our enzyme cocktail to commercial ones showed significantly better removal of different types of stains.

Conclusions

This research shows a cost-effective approach to simultaneously produce proteases, amylases, and endoglucanases from Stachybotrys microspora that could be considered a compatible detergent additive in the green detergent industry.

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

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

Effect of osmolytes on the EcoRI endonuclease: Insights into hydration and protein dynamics from molecular dynamics simulations

Osmolytes play an important role in cellular physiology by modulating the properties of proteins, including their molecular specificity. EcoRI is a model restriction enzyme whose specificity to DNA is altered in the presence of osmolytes. Here, we investigate the effect of two different osmolytes, glycerol and DMSO, on the dynamics and hydration of the EcoRI enzyme using molecular dynamics simulations. Our results show that the osmolytes, alter the essential dynamics of EcoRI. Particularly, we observe that the dynamics of the arm region of EcoRI which is involved in DNA binding is significantly altered. In addition, conformational free energy analyses reveals that the osmolytes bring about a change in the landscape similar to that of EcoRI bound to cognate DNA. We further observe that the hydration of the enzyme for each of the osmolyte is different, indicating that the mechanism of action of each of these osmolytes could be different. Further analyses of interfacial water dynamics using rotational autocorrelation function reveals that while the protein surface contributes to a slower tumbling motion of water, osmolytes, additionally contribute to the slowing of the angular motion of the water molecules. Entropy analysis also corroborates with this finding. We also find that the slowed rotational motion of interfacial waters in the presence of osmolytes contributes to a slowed relaxation of the hydrogen bonds between the interfacial waters and the functionally important residues in the protein. Taken together, our results show that osmolytes alter the dynamics of the protein by altering the dynamics of water. This altered dynamics, mediated by the changes in the water dynamics and hydrogen bonds with functionally important residues, may contribute to the altered specificity of EcoRI in the presence of osmolytes.

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

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

Expanding the bio-catalysis scope and applied perspectives of nanocarrier immobilized asparaginases

l-asparaginase is an essential enzyme in medicine and a well-known chemotherapeutic agent. This enzyme's importance is not limited to its use as an anti-cancer agent; it also has a wide variety of medicinal applications. Antimicrobial properties, prevention of infectious disorders, autoimmune diseases, and canine and feline cancer are among the applications. Apart from the healthcare industry, its importance has been identified in the food industry as a food manufacturing agent to lower acrylamide levels. When isolated from their natural habitats, they are especially susceptible to different denaturing conditions due to their protein composition. The use of an immobilization technique is one of the most common approaches suggested to address these limitations. Immobilization is a technique that involves fixing enzymes to or inside stable supports, resulting in a heterogeneous immobilized enzyme framework. Strong support structures usually stabilize the enzymes' configuration, and their functions are maintained as a result. In recent years, there has been a lot of curiosity and focus on the ability of immobilized enzymes. The nanomaterials with ideal properties can be used to immobilize enzymes to regulate key factors that determine the efficacy of bio-catalysis. With applications in biotechnology, immunosensing, biomedicine, and nanotechnology sectors have opened a realm of opportunities for enzyme immobilization.

From Enzyme Stability to Enzymatic Bioelectrode Stabilization Processes

Bioelectrocatalysis using redox enzymes appears as a sustainable way for biosensing, electricity production, or biosynthesis of fine products. Despite advances in the knowledge of parameters that drive the efficiency of enzymatic electrocatalysis, the weak stability of bioelectrodes prevents large scale development of bioelectrocatalysis. In this review, starting from the understanding of the parameters that drive protein instability, we will discuss the main strategies available to improve all enzyme stability, including use of chemicals, protein engineering and immobilization. Considering in a second step the additional requirements for use of redox enzymes, we will evaluate how far these general strategies can be applied to bioelectrocatalysis.

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

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