Purification, catalytic, kinetic and thermodynamic characteristics of a novel ficin from Ficus johannis

Purification of α-amylase from thermophilic Bacillus licheniformis SO5 by using a novel method, alternating current magnetic-field assisted three-phase partitioning: Molecular docking and bread quality improvement

A new method, alternating current magnetic field-assisted three-phase partitioning (ACMF-TPP), was performed for α-amylase purification from Bacillus licheniformis SO5. Using conventional three-phase partitioning (TPP), the enzyme achieved 105 % yield and 1.84-fold purity under optimized conditions (30 % (w/v) ammonium sulfate, 1.0:1.5 (v/v), crude extract to t-butanol ratio, pH 9.0, and 30 °C). These conditions were operated under a magnetic field with 70 % kW power and 30 % duty cycle, reducing the contact time from 1 h to 10 min, and 195 % yield and 3.07-fold purity were obtained. The optimum pH, temperature, and molecular weight for the enzyme were 7.0 and 50 °C, ∼68.7 kDa, respectively. α-Amylase showed high activity across a wide temperature range and with various substances. Molecular docking revealed that maltotriose and wheat starch showed the highest binding affinity. Bread baking tests were conducted to investigate the use of purified α-amylase in the food industry, demonstrating that the enzyme enhances bread quality.

Improved recombinant protein expression using the 5'-untranslated region in Chinese hamster ovary cells

Chinese hamster ovary (CHO) cells are major expression platforms for the transient production of recombinant therapeutic proteins (RTPs). Most improvement strategies have focused on promoting transcriptional expression in CHO cells. However, methods for promoting the yield of RTPs through translational regulation remain unclear. In this study, we investigated characteristics of the 5'-untranslated region (UTR) that influence recombinant protein expression in CHO cells and identified sequences that have positive effects on protein expression using ribosome sequencing. Some elements and characteristics of 5'-UTR differentially affected the translation of the main open reading frame and increased recombinant protein expression by 1.5-fold in CHO cells. The findings may help relieve the bottleneck of the yield of RTPs on translation enhancement.

Regeneration of selected callus of three potato cultivars (Solanum tuberosum.L) and studying their tolerance to drought stress

Drought stress poses a significant threat to potato production in Syria, necessitating the development of resilient cultivars. This study, conducted at the Plant Biotechnology Laboratory of the National Commission for Biotechnology in Damascus, investigated the impact of drought stress on key growth parameters of regenerated somaclones derived from selected callus of three potato cultivars (Solanum tuberosum L.): Salvador, Yalas, and Arizona. The research revealed striking differences in regeneration efficiency among cultivars. Yalas exhibited the highest somaclone regeneration rate at 32.1% when cultured on medium supplemented with 25 mg·L⁻1 adenine sulfate and 1.5 mg·L⁻1 BAP. Salvador and Arizona followed with regeneration rates of 21.4% and 14.5%, respectively, using 15 mg·L⁻1 adenine sulfate plus 1.5 mg·L⁻1 BAP. Comprehensive analysis of growth indicators (including plant height, leaf number and area, and root number and length) under drought stress conditions identified superior drought-tolerant somaclones. Notably, Y3 and Y2 (Yalas), S3 and S6 (Salvador), and A1 (Arizona) demonstrated exceptional drought resilience across multiple growth parameters. These findings provide valuable insights for potato breeding programs aimed at enhancing drought tolerance, potentially mitigating the impact of water scarcity on potato production in Syria and similar arid regions.

Biochemical Characterization of a Novel Cysteine Protease Purified from the Medicinal Plant Kaempferia galanga L

Plant-derived cysteine proteases have emerged as a compelling subject of investigation, capturing scientific interest owing to their potential applications in diverse industries, including food and biotechnology. This study focused on isolating Kaempferia galanga cysteine protease (KgCP) from rhizomes of Kaempferia galanga, followed by a comprehensive characterization of the protease. It was purified and characterized using various biochemical and biophysical techniques, including anion-exchange chromatography, gel filtration, SDS-PAGE electrophoresis, and enzyme assays. With a yield of 23.2%, the purification process generated a 6.03-fold increase in specific activity. KgCP's molecular weight was determined to be around 33 kDa and exhibited optimal catalytic performance at 55 °C and pH 5.5. Values of its catalytic parameters, Vmax and Km, were found to be 103.7 Units min-1 and 0.025 μmol, respectively. Inhibition of KgCP by various cysteine protease inhibitors - E-64, iodoacetamide, and mercury chloride confirmed it to be a cysteine protease. The inclusion of detergents and organic solvents did not affect the stability of KgCP. Although proteolytic activity was compromised by metal ions such as Cd2+, Co2+, and Fe3+, other metal ions (Ca2+, Mg2⁺, Mn2+, Sn2+, Sr2+, etc.) showed negligible impact on its proteolytic activity. These findings expand our understanding of the biological characteristics of this cysteine protease, highlighting its potential for applications in the dairy industry, bioactive peptide synthesis, detergents industry, etc. The entire work can be graphically presented as follows.

Structures and properties of α-amylase and glucoamylase immobilized by ZIF-8 via one-pot preparation

The immobilization of α-amylase and glucoamylase using a metal-organic framework (enzyme@ZIF-8) was prepared in situ through a one-pot method. The morphology, crystal structure, and molecular characteristics of the free enzyme and enzyme@ZIF-8 were characterized. The enzyme@ZIF-8 exhibited the rhombic dodecahedron morphology, with a decrease in particle size. Successful immobilization of α-amylase and glucoamylase within ZIF-8 was confirmed, with 30-40 % loading rate. The immobilization process did not significantly alter the crystal structure of ZIF-8. The changes in secondary structure of enzyme after immobilization resulted in modification of catalytic activity of enzyme. The melting enthalpy of enzyme @ZIF-8 increased with the increase of enzyme content. The melting peak temperature of the enzyme immobilized by ZIF-8 increased. The activity of free and immobilized enzymes was influenced by the different time, pH and temperature. At pH 5-8 and temperature 60-80 °C, the activity of the immobilized enzyme was significantly greater than that of the free enzyme. The repeatability of enzyme@ZIF-8 was 61.52 % after three cycles. The kinetic parameters of Michaelis-Menten model for enzymatic reaction were determined by fitting the initial rate of reactions and initial substrate concentration data. The Michaelis-Menten constant (KM) values of immobilized enzyme were lower than that of free enzyme, indicating the greater affinity between the enzyme and the substrate.

Comparing the effectiveness of curcumin and papain in wound dresses based on chitosan nanoparticle

In this study, chitosan/curcumin (CS/Cur) and chitosan/papain (CS/Pa) nanoparticles were prepared and then characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), and differential light scattering (DLS). Subsequently, release rate, porosity, swelling, degradability, anti-inflammatory, antioxidant, antibacterial, and cell viability tests were conducted to investigate and compare the healing potential of the nanoparticles for various types of wounds. The results of FTIR, XRD, and DLS indicated that the nanoparticles were manufactured correctly with a hydrodynamic diameter of 429 nm (CS/Cur) and 460 nm (CS/Pa), and zeta potential of 4.32 mV (CS/Cur) and 7.57 mV (CS/Pa). The release rate results indicated a higher release rate in a basic environment (pH 8.4) for curcumin, a higher release rate for papain in an acidic environment (pH 6.4), and the Korsmeyer-Peppas model for the release of curcumin and papain. The results indicated that CS/Cur with 41.6% antioxidant activity, high antibacterial effect, and cell growth up to 616% during 7 days, was more effective than CS/Pa. In comparison, CS/Pa (with a porosity of 70.5% and a swelling rate of 1392%) was more advantageous than CS/Cur in terms of porosity and swelling. In addition, CS/Cur was as effective as CS/Pa in terms of degradation and anti-inflammatory properties. In conclusion, the outcomes represented that the CS/Cur and CS/Pa nanoparticles improved wound healing, and each was suitable for specific wounds and wound healing stages.

Chitin Deacetylase from Bacillus aryabhattai TCI-16: Heterologous Expression, Characterization, and Deacetylation Performance

Chitin deacetylase (CDA) removes the acetyl group from the chitin molecule to generate chitosan in a uniform, high-quality deacetylation pattern. Herein, BaCDA was a novel CDA discovered from our previously isolated Bacillus aryabhattai strain TCI-16, which was excavated from mangrove soil. The gene BaCDA was cloned and overexpressed in Escherichia coli BL21 (DE3) to facilitate its subsequent purification. The purified recombinant protein BaCDA was obtained at a concentration of about 1.2 mg/mL after Ni2+ affinity chromatography. The molecular weight of BaCDA was around 28 kDa according to the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis. In addition, BaCDA exhibited a significant deacetylation effect on colloidal chitin, and the deacetylation degree was measured from the initial 25.69 to 69.23% by Fourier transform infrared (FT-IR) spectroscopy. Scanning electron microscopy (SEM) observation showed that the surface of colloidal chitin after enzymatic digestion was rough, the crystal fibers disappeared, and the chitin structure was loose and porous with grooves. The results of electrospray ionization mass spectrometry (ESI-MS) showed that BaCDA had full-deacetylation activity against (GlcNAc)4. Molecular docking revealed that BaCDA had an open active pocket capable of binding to the GlcNAc unit. This study not only provides a novel enzymatic resource for the green and efficient application of chitin but also helps to deepen the understanding of the catalytic mechanism of CDA.

A newly synthesized magnetic nanoparticle coated with glycidyl methacrylate monomer and 1,2,4-Triazole: Immobilization of α-Amylase from Bacillus licheniformis for more reuse, stability, and activity in the presence of H2O2

α-Amylase is a secretory enzyme commonly found in nature. The α-Amylase enzyme catalyzes the hydrolysis of α-D-(1,4)-glucosidic bonds in starch, glycogen, and polysaccharides. The chemical characterization of the composite carrier and the immobilized enzyme was performed, and the accuracy of the immobilization was confirmed by FTIR, SEM, and EDS analyses. The X-ray diffraction (XRD) analysis indicates that the magnetic nanoparticle retained its magnetic properties following the modification process. Based on the Thermogravimetric Analysis (TGA) outcomes, it was evident that the structural integrity of the FPT nanocomposite remained unchanged at 200°C. The optimal pH was determined to be 5.5, and no alteration was observed following the immobilization process. Purified α-amylases usually lose their activity rapidly above 50°C. In this study, Bacillus licheniformis α-Amylase enzyme was covalently immobilized on the newly synthesized magnetic composite carrier having more azole functional group. For novelty-designed immobilized enzymes, while there is no change in the pH and optimum operating temperature of the enzyme with immobilization, two essential advantages are provided to reduce enzyme costs: the storage stability and reusability are increased. Furthermore, our immobilization technique enhanced enzyme stability when comparing our immobilized enzyme with the reference enzyme in industrial applications. The activity of the immobilized enzyme was higher in presence of 1-3% H2O2.

Milk Protein Hydrolysis by Actinidin-Kinetic and Thermodynamic Characterisation and Comparison to Bromelain and Papain

Plant proteases, including actinidin, papain and bromelain, have been widely used in the food industry but with limited application in dairy systems. This research aimed to establish and compare operational parameters (kinetics, temperature, enzyme type, time and thermodynamics) relevant to the applications of these enzymes in the hydrolysis of whey protein isolates (WPI), whey protein concentrates (WPC) or milk protein concentrates (MPC). The degree of hydrolysis (DH) increased with the rise in temperature, and the maximum DH was achieved at 60 °C for all three dairy systems. The addition of papain resulted in a greater %DH of whey proteins in comparison to bromelain. The cleavage of proteins was clearly time-dependent (p < 0.05), while the pH did not change significantly (p > 0.05) during this time. PAGE analysis revealed that all three enzymes mainly acted on α-lactalbumin and αs-casein in WPI and MPC, respectively. Kinetic parameters from the Lineweaver-Burk plot at 60 °C using WPC and MPC as a substrate varied widely, establishing that WPC hydrolysis was characterised by a lower KM, higher kcat, kcat/KM and Vmax compared to MPC in the case of all three enzymes. The difference in kcat/KM values amongst all enzymes (actinidin > papain > bromelain) indicated the difference in the strength of substrate binding sites. The thermodynamic parameters of these enzymes with MPC and WPC were also determined at a temperature range of 15-60 °C, and the results indicate the potential application of papain and actinidin in the dairy industry.

Bromelain and ficin proteolytic effects on gliadin cytotoxicity and expression of genes involved in cell-tight junctions in Caco-2 cells

Enzyme therapy for celiac disease (CeD), which digests gliadin into non-immunogenic and non-toxic peptides, can be an appropriate treatment option for CeD. Here, we have investigated the effectiveness of bromelain and ficin on gliadin digestion using in vitro, such as SDS-PAGE, HPLC, and circular dichroism (CD). Furthermore, the cytotoxicity of gliadin and 19-mer peptide before and after digestion with these enzymes was evaluated using the MTT assay in the Caco-2 cell line. Finally, we examined the effect of these treatments along with Larazotide Acetate on the expression of genes involved in cell-tight junctions, such as Occludin, Claudin 3, tight junction protein-1, and Zonulin in the Caco-2 cell line. Our study demonstrated bromelain and ficin digestion effects on the commercial and wheat-extracted gliadin by SDS-PAGE, HPLC, and CD. Also, the cytotoxicity results on Caco-2 showed that toxicity of the gliadin and synthetic 19-mer peptide was decreased by adding bromelain and ficin. Furthermore, the proteolytic effects of bromelain and ficin on gliadin indicated the expression of genes involved in cell-tight junctions was improved. This study confirms that bromelain and ficin mixture could be effective in improving the symptoms of CeD.

An insight into microbial sources, classification, and industrial applications of xylanases: A rapid review

Endo 1,4-β-d-xylanases (EC3.2.1.8) are one of the key lignocellulose hydrolyzing enzymes. Xylan, which is present in copious amounts on earth, forms the primary substrate of endo-xylanases, which can unchain the constituent monosaccharides linked via β-1,4-glycosidic bonds from the xylan backbone. Researchers have shown keen interest in the xylanases belonging to glycoside hydrolase families 10 and 11, whereas those placed in other glycoside hydrolase families are yet to be investigated. Various microbes such as bacteria and fungi harbor these enzymes for the metabolism of their lignocellulose fibers. These microbes can be used as miniature biofactories of xylanase enzymes for a plethora of environmentally benign applications in pulp and paper industry, biofuel production, and for improving the quality of food in bread baking and fruit juice industry. This review highlights the potential of microbes in production of xylanase for industrial biotechnology.

Thermostable ficin from jelly fig (Ficus pumila var. awkeotsang) latex: purification, identification and characterization

BACKGROUND

The achenes/seeds of endemic jelly fig (Ficus pumila var. awkeotsang) fruit have been applied to prepare a traditional beverage in Taiwan. Upon fruit harvest, jelly fig latex exuded from stalks was discarded. Protease activity was monitored in its latex. Proteases capable of hydrolyzing proteins have many application aspects based on diverse characteristics. Commercial plant proteases are frequently from latex.

RESULTS

The latex protease of jelly fig, termed FaFicin, was purified to homogeneity with a molecular mass of ~32 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. According to liquid chromatographic-tandem mass spectrometric analyses, the expected protein band of protease was matched to ficin A, ficin B or chymopapain from common fig or papaya. Iodoacetamide, an inhibitor of cysteine protease, inhibited its protease activity completely. Hence FaFicin was identified as a papain-like cysteine protease (PLCP), exhibiting more than 80% and 70% activity as assayed at pH 5-8 and 40-70 °C, respectively. It maintained ~89% of initial activity after 120 min at 55 °C and pH 7. Moreover, FaFicin could degrade the myosin and actin of meat, and clot milk.

CONCLUSION

The ficin FaFicin was obtained, purified and identified as a PLCP member from agricultural waste: jelly fig latex. It possessed activity under a wide range of pH values and temperature, and exhibited excellent thermostability. Based on its initial evaluation as a meat tenderizer and milk clotting reagent, the application of FaFicin was possible, which may extend utilization of jelly fig. © 2022 Society of Chemical Industry.

In Vitro Effect on the Proteolytic Activity of Papain with Proteins of the Skin as Substrate

OBJECTIVE

This work aims to evaluate the effects of enzyme concentration, pH, temperature, and time course degree of hydrolysis (DH) of papain regarding further development of pharmaceutical and cosmetic formulations.

METHODS

The hydrolysis of casein, collagen, keratin, and porcine skin at pH and temperature ranges of the human skin was evaluated. Also, low contact times of enzyme-substrate were studied. The incorporation of 3 mM of cysteine improved the caseinolytic (PU), collagenolytic (CU), and keratinolytic (KU) activities of papain.

RESULTS

In general, the increase from 0.1 to 1.0 or 2.0 mg mL^-1 of papain improved PU, CU, and KU. When 2.0 mg mL^-1 of papain was used, the highest DH of casein, collagen, and keratin were obtained at 240 min (14, 35, and 6%, respectively). The decrease in pH and temperature reduced all proteolytic activities, but papain maintained at least 50 and 40% of its activity at 26 °C and pH 4.5, respectively. Scanning electron micrographs of the surface of the skin showed that papain application had exfoliating activity.

CONCLUSION

This pre-formulation study demonstrated that papain concentration, time of application, and pH of the product should be evaluated when developing a product to promote the hydrolysis of the proteins of the skin.

Thermally stable and acidic pH tolerant mutant phytases with high catalytic efficiency from Yersinia intermedia for potential application in feed industries

Heat- and pH-stable phytase efficiently hydrolyzes phytic acid. In this research, heat- and pH-stable mutant phytases, T⁸³R, L²⁸⁷R, and T⁸³R/L²⁸⁷R were generated by site-directed mutagenesis from Yersinia intermedia. After the induction and expression of recombinant wild-type and mutant phytases in E. coli BL21, the enzymes were purified using nickel sepharose affinity chromatography, and characterized kinetically and thermodynamically using spectroscopy methods. The mutants showed optimum activity at pH 5.15 and 55-61 °C. The catalytic efficiencies of T⁸³R, L²⁸⁷R, T⁸³R/L²⁸⁷R, and wild-type phytases were calculated to be 2941, 29346, 4906, and 6917 mmol/L^-1s^-1, respectively. Moreover, after the incubation of T⁸³R, L²⁸⁷R, wild-type, and T⁸³R/ L²⁸⁷R phytases at 100 °C for 1 h, the enzymes retained 22, 5, 4, and 2% of their initial activities, respectively. In addition, T⁸³R, T⁸³R/L²⁸⁷R, L²⁸⁷R, and wild-type phytases retained 82, 44, 16 as well as 11% of their initial activities after 1 h at pH 5.15, respectively. Among these mutants, T⁸³R mutant showed 18% increase in thermal stability, 71% increase in pH stability, and +0.103 KJ/mole increase in ΔΔG, while the catalytic efficiency and ΔΔG value of L²⁸⁷R mutant increased by 4 times and +0.0903 KJ/mole, respectively. Thus, the mutants have the potential to be used in feed industries to increase the bioavailability of minerals while decreasing soil and water pollution.

Advancement and prospects of production, transport, functional activity and structure-activity relationship of food-derived angiotensin converting enzyme (ACE) inhibitory peptides

Food-derived antihypertensive peptides have attracted increasing attention in functional foods for health promotion, due to their high biological activity, low toxicity and easy metabolism in the human body. Angiotensin converting enzyme (ACE) is a key enzyme that causes the increase in blood pressure in mammals. However, few reviews have summarized the current understanding of ACE inhibitory peptides and their knowledge gaps. This paper focuses on the food origins and production methods of ACE inhibitory peptides. Compared with conventional methods, the advanced technologies and emerging bioinformatics approaches have recently been applied for efficient and targeted release of ACE inhibitory peptides from food proteins. Furthermore, the transport and underlying mechanisms of ACE inhibitory peptides are emphatically described. Molecular modeling and the Michaelis-Menten equation can provide information on how ACE inhibitors function. Finally, we discuss the structure-activity relationships and other bio-functional properties of ACE inhibitory peptides. Molecular weight, hydrophobic amino acid residues, charge, amino acid composition and sequence (especially at the C-terminal and N-terminal) have a significant influence on ACE inhibitory activity. Some studies are required to increase productivity, improve bioavailability of peptides, evaluate their bio-accessibility and efficiency on reducing blood pressure to provide a reference for the development and application of health products and auxiliary treatment drugs.

Cohnella 1759 cysteine protease shows significant long term half-life and impressive increased activity in presence of some chemical reagents

Thermostability and substrate specificity of proteases are major factors in their industrial applications. rEla is a novel recombinant cysteine protease obtained from a thermophilic bacterium, Cohnella sp.A01 (PTCC No: 1921). Herein, we were interested in recombinant production and characterization of the enzyme and finding the novel features in comparison with other well-studied cysteine proteases. The bioinformatics analysis showed that rEla is allosteric cysteine protease from DJ-1/ThiJ/PfpI superfamily. The enzyme was heterologously expressed and characterized and the recombinant enzyme molecular mass was 19.38 kD which seems to be smaller than most of the cysteine proteases. rEla exhibited acceptable activity in broad pH and temperature ranges. The optimum activity was observed at 50℃ and pH 8 and the enzyme showed remarkable stability by keeping 50% of residual activity after 100 days storage at room temperature. The enzyme Km and Vmax values were 21.93 mM, 8 U/ml, respectively. To the best of our knowledge, in comparison with the other characterized cysteine proteases, rEla is the only reported cysteine protease with collagen specificity. The enzymes activity increases up to 1.4 times in the presence of calcium ion (2 mM) suggesting it as the enzyme's co-factor. When exposed to surfactants including Tween20, Tween80, Triton X-100 and SDS (1% and 4% v/v) the enzyme activity surprisingly increased up to 5 times.

Competitive method for fluorescent dopamine detection in cerebrospinal fluid based on the peroxidase-like activity of ficin

Dopamine (DA), a catecholamine neurotransmitter, is considered to be an important indicator for mental diseases detection in the clinic. In this study, a novel fluorescent sensing platform consisting of the ficin-H₂O₂-tyramine system for determining DA in cerebrospinal fluids (CSF) was established. The proposed method is based on the fact that ficin, a mimetic peroxidase, can catalyze H₂O₂ decomposition into OH radicals, which can oxidize non-fluorescent tyramine into fluorescent dityramine. When DA was introduced, DA can compete with tyramine for OH and resulting in the oxidation reaction of tyramine inhibited along with the fluorescence intensity of the system decreased, which provides a unique strategy for fluorescence detection of DA. Under optimal conditions, the fluorescence intensity decreased linearly with the DA level over a wide concentration range from 0.05 to 12.0 μM (R² = 0.995) with a detection limit of 46 nM (3σ/k). More importantly, the proposed sensing approach exhibits high sensitivity, good selectivity and has been successfully applied to DA sensing in complex biological samples, which made it hold great potential for DA determination in chemical and biological analytical applications.

A cysteine protease from the latex of Ficus benjamina has in vitro anthelmintic activity against Haemonchus contortus

Abstract Haemonchus contortus is a gastrointestinal nematode that is responsible for high mortality rates in ruminant herds. The resistance of nematodes to synthetic anthelmintics is widespread and requires a continuous search for new bioactive molecules, such as proteins. The objective of this study was to evaluate the anthelmintic potential of a protease purified from the latex of Ficus benjamina against H. contortus . Fresh latex was collected from plants via small incisions in the green stems, the rubber was removed by centrifugation, and the latex protein extract (LPE) was obtained. After LPE fractionation with ammonium sulfate and chromatography of the fraction containing the highest proteolytic activity on CM-cellulose, a cysteine protease (FbP) was purified. FbP has a molecular mass of approximately 23.97 kDa, and its proteolytic activity was stable between pH 6.0 and pH 10 and over a broad temperature range, with optimum activity at 60 °C. FbP inhibited both the development and exsheathment of H. contortus larvae, with 50% effective concentrations of 0.26 and 0.79 mg/mL, respectively. We conclude that this cysteine protease from F. benjamina latex with anthelmintic activity against H. contortus could be a promising alternative for the development of products for use in parasite control programmes.

Penaeus vannamei protease activating mechanism of sulfhydryl reducing compounds

For the very first time, protease enzyme from Penaeus vannamei was investigated for its activation with thiol reductant compounds. The mechanism by which sulfhydryl reductant compounds enhances the activity of P. vannamei protease still remains unclear. In this study, it was discovered that thiol-reactive compounds increase P. vannamei protease activity by a factor of about 4 with increasing V_max and decreasing Km parameters. Moreover, the reaction is an S_N2-type that does not require the initial binding of the thiol group of these compounds to the enzyme. Additionally, k₂ increased appreciably with increasing concentration of sulfhydryl reductant compounds. The linearity of this plot indicates that k₁ is unaffected by the addition of thiol compounds. Hence, the observed effect of thiol compounds on K_m seems to be due to an increase in k₂. These results suggest that the activation mechanism of P. vannamei protease almost certainly takes place by an S_N2 reaction mechanism.

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.

Penaeus vannamei protease stabilizing process of ZnS nanoparticles

The protease enzyme purified from the Penaeus vannamei shrimp has unique properties, so improving the stability of this enzyme can improve their practical applications. In this study, ZnS nanoparticles, which have special properties for enzyme immobilization, were synthesized using a chemical precipitation method, and Penaeus vannamei protease was successfully immobilized on them. The size, structure, and morphology of the ZnS nanoparticles, and the immobilization of the protease were studied, using Transmission Electron Microscopy (TEM), Fourier Transform Infrared (FT-IR) spectroscopy, UV-Vis spectroscopy and Dynamic Light Scattering (DLS) analysis. We show that the immobilized enzyme has improved functionality at high temperatures, extreme pH conditions (pH3 and 12), and during storage. Immobilization increased the optimum temperature range of the enzyme, but did not change the pH optimum, which remained at pH7. Immobilization of P. vannamei protease enzyme increased the K_m and decreased k_cat/K_m. These results indicate that P. vannamei protease immobilized on ZnS nanoparticles, has improved properties due to its high stability and unique properties, can be used for biotechnology applications.