Copper-based metal-organic frameworks (BDC-Cu MOFs) as supporters for α-amylase: Stability, reusability, and antioxidant potential.

Copper-based metal-organic frameworks (BDC-Cu MOFs) were synthesized via a casting approach using 1,4-benzene dicarboxylic (BDC) as organic ligand and their properties characterized. The obtained materials were then utilized to immobilize the α-amylase enzyme. The chemical composition and functional components of the synthesized support (BDC-Cu MOFs) were investigated with Fourier transform infrared spectroscopy (FTIR), the surface morphology was determined with scanning electron microscopy (SEM), and the elemental composition was established with energy dispersive X-ray (EDX) analyses. X-ray diffraction (XRD) was employed to analyze the crystallinity of the synthesized DBC-Cu MOFs. The zeta potentials of DBC-Cu MOFs and DBC-Cu MOFs@α-amylase were determined. The immobilized α-amylase demonstrated improved catalytic activity and reusability compared to the free form. Covalent attachment of the α-amylase to BDC-Cu provided an immobilization yield (IY%) of 81% and an activity yield (AY%) of 89%. The immobilized α-amylase showed high catalytic activity and 81% retention even after ten cycles. Storage at 4 °C for eight weeks resulted in a 78% activity retention rate for DBC-Cu MOFs@α-amylase and 49% retention for the free α-amylase. The optimum activity occurred at 60 °C for the immobilized form, whereas the free form showed optimal activity at 50 °C. The free and immobilized α-amylase demonstrated peak catalytic activities at pH 6.0. The maximum reaction velocities (Vmax) values were 0.61 U/mg of protein for free α-amylase and 0.37 U/mg of protein for BDC-Cu MOFs@α-amylase, while the Michaelis‒Menten affinity constants (Km) value was lower for the immobilized form (5.46 mM) than for the free form (11.67 mM). Treatments of maize flour and finger millet samples with free and immobilized α-amylase resulted in increased total phenolic contents. The enhanced antioxidant activities of the treated samples were demonstrated with decreased IC50 values in ABTS and DPPH assays. Overall, immobilization of α-amylase on BDC-Cu MOFs provided improved stability and catalytic activity and enhanced the antioxidant potentials of maize flour and finger millet.

Enhancing the sustainable immobilization of laccase by amino-functionalized PMMA-reinforced graphene nanomaterial.

Human health and the environment are negatively affected by endocrine-disrupting chemicals (EDCs), such as bisphenol A. Therefore, developing appropriate remediation methods is essential for efficiently removing phenolic compounds from aqueous solutions. Enzymatic biodegradation is a potential biotechnological approach for responsibly addressing water pollution. With its high catalytic efficiency and few by-products, laccase is an eco-friendly biocatalyst with significant promise for biodegradation. Herein, two novel supporting materials (NH2-PMMA and NH2-PMMA-Gr) were fabricated via the functionalization of poly(methylmethacrylate) (PMMA) polymer using ethylenediamine and reinforced with graphene followed by glutaraldehyde activation. NH2-PMMA and NH2-PMMA-Gr were utilized for laccase immobilization with an immobilization yield (IY%) of 78.3% and 82.5% and an activity yield (AY%) of 81.2% and 85.9%, respectively. Scanning electron microscope (SEM) and Fourier-transform infrared (FTIR) were used to study the characteristics of fabricated material supports. NH2-PMMA-Gr@laccase exhibited an optimal pH profile from 4.5 to 5.0, while NH2-PMMA@laccase exhibited optimum pH at 5.0 compared to a value of 4.0 for free form. A wider temperature ranges of 40-50 °C was noted for both immobilized laccases compared to a value of 40 °C for the free form. Additionally, it was reported that immobilized laccase outperformed free laccase in terms of substrate affinity and storage stability. NH2-PMMA@laccase and NH2-PMMA-Gr@laccase improved stability by up to 3.9 and 4.6-fold when stored for 30 days at 4 °C and preserved up to 80.5% and 86.7% of relative activity after ten cycles of reuse. Finally, the degradation of BPA was achieved using NH2-PMMA@laccase and NH2-PMMA-Gr@laccase. After five cycles, NH2-PMMA@laccase and NH2-PMMA-Gr@laccase showed that the residual degradation of BPA was 77% and 84.5% using 50 µm of BPA. This study introduces a novel, high-performance material for organic pollution remediation in wastewater that would inspire further progress.

Sustainable Immobilization of ß-Glucosidase onto Silver Ions and AgNPs-Loaded Acrylic Fabric with Enhanced Stability and Reusability.

Modified polymer design has attracted significant attention for enzyme immobilization, offering promising applications. In this study, amine-terminated polymers were synthesized by incorporating functional groups into polyacrylonitrile using hexamethylenediamine. This work highlights the successful enzyme immobilization strategy using modified polymers, offering improved stability and expanded operational conditions for potential biotechnological applications. The resulting amino groups were utilized to capture silver ions, which were subsequently converted to silver nanoparticles (AgNPs). The obtained materials, AgNPs@TA-HMDA (acrylic textiles coated silver nanoparticles AgNPs) and Ag(I)@TA-HMDA (acrylic textiles coated with Ag ion) were employed as supports for ß-glucosidase enzyme immobilization. The highest immobilization yields (IY%) were achieved with AgNPs@TA-HMDA at 92%, followed by Ag(I)@TA-HMDA at 79.8%, resulting in activity yields (AY%) of 81% and 73%, respectively. Characterization techniques such as FTIR, FE-SEM, EDX, TG/DTG, DSC, and zeta potential were employed to investigate the structural composition, surface morphologies, elemental composition, thermal properties, and surface charge of the support materials. After 15 reuses, the preservation percentages decreased to 76% for AgNPs@TA-HMDA/ß-Glu and 65% for Ag(I)@TA-HMDA/ß-Glu. Storage stability revealed that the decrease in activity for the immobilized enzymes was smaller than the free enzyme. The optimal pH for the immobilized enzymes was broader (pH 5.5 to 6.5) compared to the free enzyme (pH 5.0), and the optimal temperature for the immobilized enzymes was 60 °C, slightly higher than the free enzyme's optimal temperature of 50 °C. The kinetic analysis showed a slight increase in Michaelis constant (Km) values for the immobilized enzymes and a decrease in maximum velocity (Vmax), turnover number (Kcat), and specificity constant (Kcat/Km) values compared to the free enzyme. Through extensive characterization, we gained valuable insights into the structural composition and properties of the modified polymer supports. This research significantly contributes to the development of efficient biotechnological processes by advancing the field of enzyme immobilization and offering valuable knowledge for its potential applications.

Chitosan-Based metal-organic framework for Stabilization of ß-glucosidase: Reusability and storage stability.

Enzyme immobilization is a powerful tool for protecting enzymes from harsh reaction conditions and improving enzyme activity, stability, and reusability. In this study, metal organic frameworks (MIL-Fe composites) were synthesized via solvothermal reactions and then modified with chitosan (CS). ß-Glucosidase was immobilized on the chitosan-metal organic framework (CS-MIL-Fe), and the resulting composites were characterized with various analytical techniques. The ß-glucosidase immobilized on a CS-MIL-Fe composite had an immobilization yield of 85 % and a recovered activity of 74 %. The immobilized enzyme retained 81 % of its initial activity after ten successive cycles and preserved 69 % of its original activity after 30 days of storage at 4 °C. In contrast, the free enzyme had only preserved 32 % of its original activity after 30 days. Under various temperature and pH conditions, the immobilized enzyme showed greater stability than the free enzyme, and the optimal temperature and pH were 60 °C and 6.0 for the immobilized enzyme and 50 °C and 5.0 for the free enzyme. The kinetic parameters were also determined, with the Km values of 13.4 and 6.98 mM for the immobilized and free ß-glucosidase, respectively, and Vmax values of 3.96 and 1.72 U/mL, respectively. Overall, these results demonstrate that the CS-MIL-Fe@ß-glucosidase is a promising matrix showing high catalytic efficiency and enhanced stability.

Novel and Facile Colorimetric Detection of Reducing Sugars in Foods via In Situ Formed Gelatin-Capped Silver Nanoparticles.

The evolution of green technology for the simple and ecological formation of silver nanoparticles (AgNPs) inspired the present work for simple and efficient detection of reducing sugars (RS) in foods. The proposed method relies on gelatin as the capping and stabilizing agent and the analyte (RS) as the reducing agent. This work may attract significant attention, especially in the industry, for testing the sugar content using gelatin-capped silver nanoparticles as it not only detects the sugar in food, but also determines the content (%), which could be an alternative technique to the conventionally used DNS colorimetric method. For this purpose, a certain amount of maltose was mixed with a gelatin-silver nitrate. Different conditions that may affect the color changes at 434 nm owing to the in situ formed AgNPs, such as gelatin-silver nitrate ratio, PH, time, and temperature, have been investigated. The 1:3 mg/mg ratio of gelatin-silver nitrate dissolved in 10 mL distilled water was most effective in color formation. The development of AgNPs color increases within 8-10 min at PH 8.5 as the selected optimum value and at the optimum temperature of 90 °C for the evolution of the gelatin-silver reagent's redox reaction. The gelatin-silver reagent showed a fast response (less than 10 min) with a detection limit for maltose at 46.67 µM. In addition, the selectivity of maltose was checked in the presence of starch and after its hydrolysis with α-amylase. Compared with the conventionally used dinitrosalicylic acid (DNS) colorimetric method, the proposed method could be applied to commercial fresh apple juice, watermelon, and honey to prove its viability for detecting RS in fruits; the total reducing sugar content was 287, 165, and 751 mg/g, respectively.

GC-MS Analysis of Bioactive Compounds Extracted from Plant Rhazya stricta Using Various Solvents.

Worldwide, human beings have traditionally employed many folkloric herbal resources as complementary and alternative remedies, and these remedies have played a pivotal role in modern medicines for many decades, as scientists have used them to develop drugs. We studied the effects of employing solvents with varying polarity on the yields of phytochemical components extracted from the plant Rhazya stricta. We used chloroform-methanol (1:1), methanol, ethanol, diethyl ether, and ethyl acetate as extraction solvents. The results showed that the efficiencies of the solvents at extracting phytochemical compounds were in this order: chloroform-methanol < ethanol < methanol < diethyl ether < ethyl acetate extract. The chloroform-methanol extract produced the highest concentration of phenolic and flavonoid contents among the five solvents tested (13.3 mg GAE/g DM and 5.43 CE/g DM). The yields of the extracted phytochemical compounds ranged from 47.55 to 6.05%. The results revealed that the properties of the extraction solvents considerably impacted the extraction yield and the phytochemical components of the R. stricta extract. Furthermore, compared with the other solvents, the chloroform-methanol extraction led to the highest yield (47.55%) and to more phytochemical substances being extracted. The aim of this study is to investigate the phytochemical compounds extracted from R. stricta with different solvents that have different polarities.

Synthesis and Characterization of Aminoamidine-Based Polyacrylonitrile Fibers for Lipase Immobilization with Effective Reusability and Storage Stability.

Lipases are extensively utilized industrial biocatalysts that play an important role in various industrial and biotechnological applications. Herein, polyacrylonitrile (PAN) was treated with hexamethylene diamine (HMDA) and activated by glutaraldehyde, then utilized as a carrier support for Candida rugosa lipase. In this regard, the morphological structure of modified PAN before and after the immobilization process was evaluated using FTIR and SEM analyses. The immobilized lipase exhibited the highest activity at pH 8.0, with an immobilization yield of 81% and an activity of 91%. The optimal pH and temperature for free lipase were 7.5 and 40 °C, while the immobilized lipase exhibited its optimal activity at a pH of 8.0 and a temperature of 50 °C. After recycling 10 times, the immobilized lipase maintained 76% of its activity and, after 15 reuses, it preserved 61% of its activity. The lipase stability was significantly improved after immobilization, as it maintained 76% of its initial activity after 60 days of storage. The calculated Km values were 4.07 and 6.16 mM for free and immobilized lipase, and the Vmax values were 74 and 77 µmol/mL/min, respectively. These results demonstrated that synthetically modified PAN is appropriate for immobilizing enzymes and has the potential for commercial applications.

Acrylic fabric and nanomaterials to enhance α-amylase-based biocatalytic immobilized systems for industrial food applications.

An innovative approach for immobilizing α-amylase was used in this investigation. The acrylic fabric was first treated with hexamethylene diamine (HMDA) and then coated with copper ions that were later reduced to copper nanoparticles (CuNPs). The corresponding materials obtained, Cu(II)@HMDA-TA and CuNPs@HMDA-TA, were employed as carriers for α-amylase, respectively. The structural and morphological characteristics of the produced support matrices before and after immobilization were assessed using various techniques, including FTIR, SEM, EDX, TG/DTG, DSC, and zeta potential. The immobilized α-amylase exhibited the highest level of activity at pH 7.0, with immobilization yields observed for CuNPs@HMDA-TA (81.7 %) (60 unit/g support) followed by Cu(II)@HMDA-TA (71.7 %) (49 unit/g support) and 75 % and 61 % of activity yields, and 91.7 % and 85 % of immobilization efficiency, respectively. Meanwhile, biochemical characterizations of the activity of the soluble and immobilized enzymes were carried out and compared. Optimal temperature, pH, kinetics, storage stability, and reusability parameters were optimized for immobilized enzyme activity. The optimal pH and temperature were recorded as 6.0 and 50 °C for soluble α-amylase while the two forms of immobilized α-amylase exhibit a broad pH of 6.0-7.0 and optimal temperature at 60 °C. After recycling 15 times, the immobilized α-amylase on CuNPs@HMDA-TA and Cu(II)@HMDA-TA preserved 63 % and 52 % of their activities, respectively. The two forms of immobilized α-amylase displayed high stability when stored for 6 weeks and preserved 85 % and 76 % of their activities, respectively. Km values were calculated as 1.22, 1.39, and 1.84 mg/mL for soluble, immobilized enzymes on CuNPs@HMDA-TA, and Cu(II)@HMDA-TA, and Vmax values were calculated as 36.25, 29.68, and 21.57 µmol/mL/min, respectively. The total phenolic contents of maize kernels improved 1.4 ± 0.01 fold after treatment by two immobilized α-amylases.

Polyester fabric modification by chemical treatment to enhancing the ß-glucosidase immobilization.

This work reports the first approach to immobilizing the ß-glucosidase enzyme on a modified polyester fabric support matrix. Herein, polyester fabric was successfully fabricated with hydrazide groups incorporated with graphene oxide, followed by glyoxal as the crosslinker. Various techniques, including Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimeter, and zeta potential analysis, were used to investigate their microstructural, dispersive, thermal, and physicochemical properties. ß-glucosidase immobilization exhibited maximum activity at pH 6.0 with an immobilization yield (89.5%), immobilization efficiency (92%), and enzyme activity yields (82.3%). After fifteen reaction cycles, the remaining enzyme activity was 59%. Stored at 4 °C, immobilized ß-glucosidase retained 74% of its activity, compared to a retain of 43% for soluble ß-glucosidase, during the 6-weeks period. Soluble and immobilized enzyme exhibited similar optimal catalytic temperature at 60 °C, while the optimal catalytic pH was 5 and 6, respectively. Both soluble and immobilized ß-glucosidase presented Michaelis-Menten kinetics with Vmax values of 1.82 and 2.94 U/mg, and Km values of 2.94 and 5.15 mM, respectively. This research provided a potential directed immobilization method for ß-glucosidase, and robust biocatalyst for industrial applications.

In Situ Coating of Polydopamine-AgNPs on Polyester Fabrics Producing Antibacterial and Antioxidant Properties.

Nanoparticles are increasingly utilized as coating materials to improve the properties of polyester textiles. In this work, polyester textiles were successfully fabricated, with hydrazide groups serving as ligands for the entrapment of sliver ions and subsequent reduction to AgNPs. Polydopamine (PDA) was used in this work to impart antibacterial and antioxidant properties to the polyester textiles through its phenolic hydroxyl groups, which can convert silver ions into AgNPs. Moreover, glucose was used as a reducing agent to create AgNPs-loaded polyester hydrazide. ATR-FTIR, SEM, EDX, thermogravimetric analysis (TGA), and tensile strength were used to characterize the pristine polyester, the polyester hydrazide, the PDA-coated AgNP-loaded polyester hydrazide and the AgNP-loaded polyester hydrazide. A broth test was also used to investigate the textile's antimicrobial activities against Escherichia coli and Staphylococcus aureus. Overall, the composite nanocoating with PDA-AgNPs demonstrated good tensile strength and antioxidant and antibacterial characteristics, implying the practicality of PDA-AgNPs coating polyester for biomedical textile applications.

Multi-enzyme co-immobilized nano-assemblies: Bringing enzymes together for expanding bio-catalysis scope to meet biotechnological challenges.

Co-immobilization of multi-enzymes has emerged as a promising concept to design and signify bio-catalysis engineering. Undoubtedly, the existence and importance of basic immobilization methods such as encapsulation, covalent binding, cross-linking, or even simple adsorption cannot be ignored as they are the core of advanced co-immobilization strategies. Different strategies have been developed and deployed to green the twenty-first century bio-catalysis. Moreover, co-immobilization of multi-enzymes has successfully resolved the limitations of individual enzyme loaded constructs. With an added value of this advanced bio-catalysis engineering platform, designing, and fabricating co-immobilized enzymes loaded nanostructure carriers to perform a particular set of reactions with high catalytic turnover is of supreme interest. Herein, we spotlight the emergence of co-immobilization strategies by bringing multi-enzymes together with various types of nanocarriers to expand the bio-catalysis scope. Following a brief introduction, the first part of the review focuses on multienzyme co-immobilization strategies, i.e., random co-immobilization, compartmentalization, and positional co-immobilization. The second part comprehensively covers four major categories of nanocarriers, i.e., carbon based nanocarriers, polymer based nanocarriers, silica-based nanocarriers, and metal-based nanocarriers along with their particular examples. In each section, several critical factors that can affect the performance and successful deployment of co-immobilization of enzymes are given in this work.

Role of leukotriene pathway and montelukast in pulmonary and extrapulmonary manifestations of Covid-19: The enigmatic entity.

Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2), the responsible agent for the coronavirus disease 2019 (Covid-19), has its entry point through interaction with angiotensin converting enzyme 2 (ACE2) receptors, highly expressed in lung type II alveolar cells and other tissues, like heart, pancreas, brain, and vascular endothelium. This review aimed to elucidate the potential role of leukotrienes (LTs) in the pathogenesis and clinical presentation of SARS-CoV-2 infection, and to reveal the critical role of LT pathway receptor antagonists and inhibitors in Covid-19 management. A literature search was done in PubMed, Scopus, Web of Science and Google Scholar databases to find the potential role of montelukast and other LT inhibitors in the management of pulmonary and extra-pulmonary manifestations triggered by SARS-CoV-2. Data obtained so far underline that pulmonary and extra-pulmonary manifestations in Covid-19 are attributed to a direct effect of SARS-CoV-2 in expressed ACE2 receptors or indirectly through NF-κB dependent induction of a cytokine storm. Montelukast can ameliorate extra-pulmonary manifestations in Covid-19 either directly through blocking of Cys-LTRs in different organs or indirectly through inhibition of the NF-κB signaling pathway.

Hydroxyapatite-decorated ZrO2 for α-amylase immobilization: Toward the enhancement of enzyme stability and reusability.

Herein, the immobilization of α-amylase onto hydroxyapatite (HA) and hydroxyapatite-decorated ZrO2 (10%wt) (HA-ZrO2) nanocomposite were investigated. The immobilization yield was 69.7% and 84% respectively. The structural differences were characterized using X-Ray diffraction, attenuated total reflectance-Fourier transform infrared spectra, Raman, and scanning electron microscope. After 10 repeated cycles, the residual activity of immobilized α-amylase onto HA and HA-ZrO2 nanocomposite was 46% and 70%, respectively. The storage stability was recorded to be 27%, 50% and 69% from its initial activity in the case of free and immobilized enzyme onto HA and HA-ZrO2 nanocomposite, respectively after 8 weeks. The pH-activity profile and temperature revealed pH 6.0 and temperature 50 °C as the optimal values of free α-amylase, while the optimum values for α-amylase on HA and HA-ZrO2 was shifted to pH 6.5 and 60 °C after immobilization. The immobilized α-amylase onto HA-ZrO2 showed comparatively higher catalytic activity than the free α-amylase. The Km value after the immobilization process onto HA was 2.1 folds highly than that of the free enzyme. In conclusion, it can be inferred that HA-ZrO2 is more sustainable and beneficial support for enzyme immobilization and it represents promising supports for different uses of α-amylase in the biomedical applications.

Covalent organic frameworks as emerging host platforms for enzyme immobilization and robust biocatalysis - A review.

In recent years, the synthesis and application of green and sustainable products have become global ecological and societal issues. Based on the principles of green chemistry, the application of different biocatalysts not only produce target products and decreases side effects but also enhances the selectivity and activity. Enzyme-based biocatalysts are very interesting due to their high catalytic performance, eco-friendly reaction systems, and selectivity. Immobilization is demonstrated as a favorable approach to improve the stability and recyclability of enzymes. Among different supports, porous and crystalline materials, covalent organic frameworks (COFs), represent an interesting class of support matrices for the immobilization of different enzymes. Owing to tunable physicochemical characteristics, a high degree of crystallinity, large specific surface area, superior adsorption capacity, pre-designable structure and marked stability, COFs might consider as perfect host materials for improving the desirable properties of enzymes, such as poor stability, low operational range, lack of repeatability, and products/by-products inhibition for large-scale applications. The enzyme-incorporated COFs have emerged as one of the hopeful ways to constitute tailor-made biocatalytic systems, which can be employed in an array of reactions. Highly porous nature of many COFs led to increased process output in contrast to other micro/nanoparticles. The enzymes can be integrated into COFs through different techniques, including physical adsorption and direct covalent attachment between the enzyme molecules and COFs or through a cross-linking agent. Herein, we discuss and highlight the synthesis methods, properties, and functionalization of COFs and the recent literature for the application of these materials in enzymes immobilization. Main approaches for immobilization of enzymes into COFs and the catalytic applications of these materials are also presented. This study offers new avenues to address the limitations of traditional enzyme immobilization supports as well as delivers new possibilities to construct smart biocatalytic systems for diverse biotechnological applications.

Dual immobilization of α-amylase and horseradish peroxidase via electrospinning: A proof of concept study.

In this work, we propose a facile technique to dually-immobilize α-amylase and horseradish peroxidase (HRP) as two different enzyme models via entrapment within two distinct polymeric electrospun fibers by simple mixing steps and compare their properties with both individually immobilized forms and with the free counterparts. The immobilization was verified using Fourier transform infrared spectroscopy (FTIR) and Field emission scanning electron microscope (FESEM). The immobilization efficiencies for the dual-immobilized HRP and α-amylase were 89% and 85%, respectively. The retained catalytic activities of the dual-immobilized HRP and α-amylase enzymes were observed to be 79% and 80.2% after 10 cycles, respectively. After storage for 12 weeks, the dual-immobilized enzymes still retained nearly 90% activities similar to the individually immobilized ones. This immobilization procedure did not appear to exert either negative or back inhibitory effects upon both enzymes with respect to the different enzymatic assay procedures. This approach demonstrates that two or more type of enzymes could be mixed with different polymers individually and undergoes electrospinning simultaneously. We believe that this approach is expected to considerably promote and extend the application of multi-enzyme systems and worth further investigation for potential enzyme mediated cascade reactions.

Purification and biochemical characterization of Arabian balsam α-amylase and enhancing the retention and reusability via encapsulation onto calcium alginate/Fe2O3 nanocomposite beads.

In this study, Arabian balsam α-amylase was purified using the three-step purification method with 9.8-fold purification and 7% recovery. The purified α-amylase's molecular weight was 85 kDa. Calcium alginate incorporated with iron (III) oxide nanoparticles was applied as an immobilizing support for α-amylase. The immobilized α-amylase was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. In addition, the optimum conditions for immobilization efficiency, immobilization time, reusability, kinetic parameters, and the effect of pH for the immobilization process were examined. After storage, about 87% of the initial activity was maintained at 4 °C for 60 days. The immobilized enzyme exhibited enhanced stability compared to the soluble enzyme in relation to pH and temperature. The immobilized enzyme provided the following kinetic variables: 0.455 mg/mL, 4050 s-1, 28.57 µmol maltose/mL, and 8900 s-1 mg-1 mL for Km, kcat, Vmax, and kcat/Km, respectively, compared with 1.798 mg/mL, 5980 s-1, 42.19 µmol maltose/mL, and 3326 s-1 mg-1 mL for the soluble enzyme. The total phenolic contents of the soluble and immobilized α-amylase-treated wheat kernels were increased by 1.26 and 1.31 fold, respectively. Purified α-amylase from Arabian balsam can thus be successfully used to enhance the antioxidant capacity of cereals.

A novel peroxidase from Ziziphus jujuba fruit: purification, thermodynamics and biochemical characterization properties.

In this study, peroxidase from Ziziphus jujuba was purified using ion exchange, and gel filtration chromatography resulting in an 18.9-fold enhancement of activity with a recovery of 20%. The molecular weight of Z. jujuba peroxidase was 56 kDa, as estimated by Sephacryl S-200. The purity was evaluated by SDS, which showed a single prominent band. The optimal activity of the peroxidase was achieved at pH 7.5 and 50 °C. Z. jujuba peroxidase showed catalytic efficiency (Kcat/Km) values of 25 and 43 for guaiacol and H2O2, respectively. It was completely inactivated when incubated with ß-mercaptoethanol for 15 min. Hg2+, Zn2+, Cd2+, and NaN3 (5 mM) were effective peroxidase inhibitors, whereas Cu2+ and Ca2+ enhanced the peroxidase activity. The activation energy (Ea) for substrate hydrolysis was 43.89 kJ mol-1, while the Z value and temperature quotient (Q10) were found to be 17.3 °C and 2, respectively. The half-life of the peroxidase was between 117.46 and 14.15 min. For denaturation of the peroxidase, the activation energy for irreversible inactivation Ea*(d) was 120.9 kJmol-1. Thermodynamic experiments suggested a non-spontaneous (∆G*d > 0) and endothermic reaction phase. Other thermodynamic parameters of the irreversible inactivation of the purified enzyme, such as ∆H* and ∆S*, were also studied. Based on these results, the purified peroxidase has a potential role in some industrial applications.

Immobilisation of α-amylase on activated amidrazone acrylic fabric: a new approach for the enhancement of enzyme stability and reusability.

In this study, amidrazone acrylic fabric was applied as an immobilising support for α-amylase. The immobilised α-amylase was characterised by Fourier transform infrared spectroscopy and scanning electron microscopy. Furthermore, the optimum conditions for immobilisation efficiency, immobilisation time, reusability, kinetic parameters and pH, for the immobilisation process were examined. The study demonstrated that with 4% cyanuric chloride, and a pH of 7.0, the highest immobilization efficiency of 81% was obtained. Around 65% of the initial activity was maintained after storage at 4 °C for 8 weeks. The immobilised enzyme retained 53% of its original activity after being reused 15 times and exhibited improved stability compared with the free enzyme in relation to heavy metal ions, pH, temperature and inhibitors. The immobilised enzyme presented kinetic parameters of 2.6 mg starch and 0.65 µmol maltose/mL for Km and Vmax respectively, compared with 3.7 mg starch and 0.83 µmol maltose/ mL for the free enzyme. The improvements in the enzyme's catalytic properties, stability and reusability obtained from immobilisation make amidrazone acrylic fabric support a good promising candidate for bio-industrial applications.

Amidrazone modified acrylic fabric activated with cyanuric chloride: A novel and efficient support for horseradish peroxidase immobilization and phenol removal.

In this study, hydrazine treated acrylic fabrics (polyacrylonitrile, PAN) activated with cyanuric chloride was developed as supporting material for horseradish peroxidase (HRP) immobilization. The immobilization of HRP onto the modified supporting material was achieved after being end-over-end incubated for 12 h. Field emission scanning electron microscopy and Fourier-transform infrared spectroscopy techniques were used to confirm the successful immobilization. Reusability experiment was performed to estimate the ability of the immobilized HRP to recover the reaction medium, in which it was observed to retain 78% of its original activity after 10 cycles. Relative to the soluble HRP, the optimum pH and temperature for the immobilized HRP were shifted to 7-7.5 and 50 °C, respectively. The kinetic parameters of guaiacol and H2O2 for the immobilized HRP were determined to be Km/Vmax = 57.61, 11.35 and Kcat/Km = 1.87, 1.86, respectively, while the values for the free form were Km/Vmax = 41.49, 6.23 and Kcat/Km = 1.87, 1.86, respectively. Compared to the soluble form, the immobilized HRP exhibited higher resistance toward metal ions and some organic solvents. For an application perspective. The immobilization of HRP using this procedure has the potential to be used for industrial application and wastewater treatment.

A novel peroxidase from Arabian balsam (Commiphora gileadensis) stems: Its purification, characterization and immobilization on a carboxymethylcellulose/Fe3O4 magnetic hybrid material.

A novel plant peroxidase was isolated from the stem of Arabian balsam (Commiphora gileadensis) and purified using ammonium sulfate, followed by ion exchange chromatography (DEAE-Sepharose) and gel filtration (Sephcryl S-200). The newly isolated peroxidase was characterized as having a specific activity of 9503.3 unit/mg of protein after 20.3-fold purification, which yielded a recovery of 18.5%. Based on the subunit size, the purified peroxidase was a 40 kDa monomeric structure and presented high thermostability, as it was entirely stable at 55 °C for 30 min and retained approximately 13.6% of its activity at 85 °C. The optimal pH exhibited a broad value range (pH 7.0- 7.5). The kinetic parameters for the purified peroxidase were obtained. To increase the enzyme durability, efficiency and reusability, the peroxidase was entrapped onto a carboxymethyl cellulose/Fe3O4 magnetic hybrid material. The immobilized enzyme was characterized by scanning electron microscopy (SEM) and FT-IR spectroscopy. It was tested at different pH values, storage times and temperatures, and its kinetic behavior was assessed. The immobilized enzyme maintained its activity upon storage at 4 and 25 °C for 8 weeks, and upon recycling for up to 15 uses. Arabian balsam peroxidase appears to be candidate for industrial applications.