Is enzyme immobilization a mature discipline? Some critical considerations to capitalize on the benefits of immobilization

Cytochrome P450 electrochemical biosensors transforming in vitro metabolism testing - Opportunities and challenges

The ability of the living world to flourish in the face of constant exposure to dangerous chemicals depends on the management ability of a widespread group of enzymes known as heme-thiolate monooxygenases or cytochrome P450 superfamily. About three-quarters of all reactions determining the metabolism of endogenous compounds, of those carried in foods, of taken drugs, or even of synthetic chemicals discarded into the environment depend on their catalytic performance. The chromatographic and (photo)luminometric methods routinely used as predictive and analytical tools in laboratories have significant drawbacks ranging from limited shelf-life of reagents, use of synthetic substrates, laborious and tedious procedures for highly sensitive detection. In this review, alternative electrochemical biosensors using the cytochrome P450 enzymes as bio-element are emphasized in their main aspects as well regarding their implementation and usefulness. Despite the various schemes proposed for the implementation, reports on real applications are scant for several reasons, including low reaction rates, broad substrate specificity, uncoupling reactions occurrence, and the need for expensive electron transfer partners to promote electron transfer. Finally, the prospect for future developments is introduced, focusing on integrating miniaturized systems with electrochemical techniques, alongside optimizing enzyme immobilization methods and electrode modifications to improve enzymatic stability and enhance sensor reliability. This progress represents a crucial step towards the creation of portable biosensors that mimic human physiological responses, supporting the precision medicine approach.

A comprehensive review of lipase-catalyzed acidolysis as a method for producing structured glycerides

The production of structured lipids is a current trend in food technology in order to enhance the properties of fats and oils. Lipases have been utilized in many instances for this purpose, in most examples in an immobilized form. In this review, after discussing the different strategies to produce artificial lipids using lipases (esterification, transesterification, interesterification), we have focused on acidolysis. The reaction commences with hydrolysis at one position of the triglyceride molecule and is followed by the esterification between the released hydroxyl group and the target fatty acid (although other carboxylic acids can be used, such as phenolic acid derivatives). This means that water plays a double role, as substrate in the first step and as an undesired by-product in the second one. Therefore, the control of water activity becomes critical in these reactions. This review discusses the advantages, possibilities and drawbacks of this strategy to produce tailor-made designed lipids, summarizing many of the papers related to this strategy. The summarized results show the complexity of this reaction that can make the understanding and reproducibility of the reactions complex if there are no strict controls of all parameters determining the final yields.

Advanced enzyme-assembled hydrogels for the remediation of contaminated water

Enzyme-catalyzed biodegradation is an emerging green strategy for environmental remediation, although challenged by high cost and poor robustness. Herein, natural biopolymer (cellulose)-derived hydrogels concurrently doped with β-cyclodextrin and montmorillonite nanosheets that are synthesized in one-step demonstrate exceptional pollutant affinity and mechanical strength. Laccase is then stably and effectively assembled onto the hydrogels by a facile strategy based on charge-assisted H-bonding, which can be extended to other enzymes. The advanced laccase-assembled hydrogels display excellent stability and increased degradation activity achieved by strong substrate capture and rapid electron transfer. The laccase-assembled hydrogels exhibit significantly improved removal (62-fold) and degradation (52-fold) performance compared to free laccase for diverse organic pollutants (e.g., polycyclic aromatic hydrocarbons) in real wastewater. This enhanced performance is maintained despite the presence of heavy metals, other organic chemicals or dissolved organic matter. This work provides a practical strategy for designing an advanced and sustainable biodegradation tool for environmental remediation.

Structural Stabilization and Activity Enhancement of Glucoamylase via the Machine-Learning Technique and Immobilization

Glucoamylases (GLL) hydrolyze starch to glucose syrup without yielding intermediate oligosaccharides, but their lack of stability under industrial conditions poses a major limiting factor. Using consensus- and ancestral-based machine-learning tools, a functional GLL with six mutations (GLLI73l/T130V/N212V/D238G/N327M/S332P) was constructed that exhibited superior hydrolytic activity relative to the wild-type (WT-GLL). An oxidized multi-walled carbon nanotube (oMW-CNT) was used as a solid support to immobilize the WT-GLL with an immobilization capacity of 211.28 mg/g. The specific activity of mutant GLL-6M and GLL@oMW-CNTII was improved by 2.5-fold and 3.9-fold respectively, with both retaining 64.5% residual activity after incubation at 50 °C for 2 h compared to the WT-GLL with 42.6% activity. GLL and GLL-6M were however completely inactivated at 55 °C in 30 min while oMW-CNTII retained ∼43.1% activity. Our results demonstrate that employing a machine-learning approach for enzyme redesign and immobilization is a practicable alternative for improving enzyme performance and stability for industrial applications.

Alcalase immobilization in iota-carrageenan-matrix hydrogel beads derived from the macroalga Solieria filiformis

This study aims to immobilize Bacillus licheniformis (Alcalase) protease in iota-carrageenan (ιCAR) matrix hydrogels via adsorption. CAR was extracted from macroalgae Solieria filiformis and used to produce hydrogels using Al3 + as the gelling agent. Subsequently, enzyme immobilization was performed at 25ºC, for 120 min using particles of ∼2.0 mm diameter, varying the medium pH values (7.0, 8.0, and 9.0). The immobilization at pH 8.0 resulted in the biocatalyst with the highest immobilization yield (100 %), expressed activity (88.9 %), and mass activity (10.4 U/g) for 1.0 mg/g of enzyme loading. When using particles with different diameters (1.0, 2.0, and 3.0 mm), the best results were obtained using 1.0 mm particles. This permitted a 100 % immobilization yield, 95.8 % expressed activity, and high mass activity (11.2 U/g). The lyophilized biocatalyst presented varying macro-pore diameters, ranging from 21 to 126 µm. The immobilized biocatalyst was 11 times more stable than the soluble enzyme at 60ºC and pH 8.0 and presented > 80 % retained activity in the pH range 6.0-9.0.

A new β-amylase detection strategy based on encapsulated enzyme in magnetic layered double hydroxide with high sensitivity and simplified workflow

β-Amylase (BMY) is a linchpin in food production and the pharmaceutical industry because the enzyme efficiently controls the ratio of diverse saccharides in fermentation and the manufacture of high-quality maltose. However, existing BMY detection tactics suffer from inadequate selectivity/sensitivity and cumbersome operation and do not meet the needs of precise quantification. Consequently, there is an urgent need to develop an ultrasensitive sensing platform to achieve precise BMY analysis with a low detection limit and simpler workflow. In this work, we establish an encapsulated-enzyme-based BMY biosensing platform in which α-glucosidase is embedded in magnetic layered double hydroxide using a self-sacrificing template. The encapsulated enzyme has increased activity, robustness, and recyclability and was utilized for BMY detection via a cascade chromatic process. We found a detection limit for the quantification of BMY activity of 2.67 U/L with a broad range (5-400 U/L), fast response speed (10 min), and satisfactory specificity. We applied the biosensing platform to liquor starters to verify the capability of the assay in complicated fermentation samples. The proposed platform holds great promise as an efficient and simple method for enzymatic bioactivity monitoring in food manufacturing, biopharmaceutical processing, and clinical laboratory tests.

Sustainable bioactive hydrogels for organic contaminant elimination in wastewater

Immobilized enzyme bioremediation is a promising technique for eliminating pollutants to alleviate water scarcity pressure but is severely hindered by poor enzymatic activity and stability. An effective charge-assisted H-bonding approach is developed to achieve high laccase loading and enzymatic activity on bio(cellulose)-based hydrogels. Notably, this strategy can be readily extended to lipase and catalase. The bio-based hydrogels are synthesized by grafting deoxyribonucleic acid onto the cellulose backbone through a one-step structural regulation, achieving high mechanical strength, enzyme loading and contaminant capture for degradation. The biocompatible laccase-immobilized hydrogels exhibit significant removal and degradation performance for diverse organic micropollutants, including parent and substituted polycyclic aromatic hydrocarbons, per- and polyfluoroalkyl substances, antibiotics and organic dyes. Further testing focused on parent and substituted polycyclic aromatic hydrocarbons shows minimal influence of various co-existing interfering substances on performance of the laccase-immobilized bioactive hydrogel, with its contaminant removal and degradation efficiency in authentic wastewater being 93.0- and 64.3-fold that of commercial free laccase, respectively. This work provides an effective strategy for sustainable bioremediation of wastewater and other pollutant streams, while simultaneously enabling the development of innovative enzyme catalysts.

Laccase-based biocatalytic systems application in sustainable degradation of pharmaceutically active contaminants

The outflow of pharmaceutically active chemicals (PhACs) exerts a negative impact on biological systems even at extremely low concentrations. For instance, enormous threats to human and aquatic species have resulted from the widespread use of antibiotics in ecosystems, which stimulate the emergence and formation of antibiotic-resistant bacterial species and associated genes. Additionally, it is challenging to eliminate these PhACs by employing conventional physicochemical water treatment techniques. Enzymatic approaches, including laccase, have been identified as a promising alternative to eliminate a broad array of PhACs from water matrices. However, their application in environmental bioremediation is hindered by several factors, including the enzyme's stability and its location in the aqueous environment. Such obstacles may be surmounted by employing laccase immobilization, which enables enhanced stability (including inactivation caused by the substrate), and thus improved catalysis. This review emphasizes the potential hazards of PhACs to aquatic organisms within the detection concentration range of ngL-1 to µgL-1, as well as the deployment of laccase-based multifunctional biocatalytic systems for the environmentally friendly mitigation of anticancer drugs, analgesics/NSAIDs, antibiotics, antiepileptic agents, and beta blockers as micropollutants. This approach could reduce the underlying toxicological consequences. In addition, current developments, potential applications, and viewpoints have focused on computer-assisted investigations of laccase-PhACs binding at enzyme cavities and degradability prediction.

Effect of the support alkyl chain nature in the functional properties of the immobilized lipases

Supports coated with amino-hexyl and amino octyl have been prepared from glyoxyl agarose beads and compared in their performance with octyl-agarose to immobilize lipases A and B from Candida antarctica (CALA and CALB). Immobilization courses were similar using all supports, but enzyme release was more difficult using the amino-alkyl supports suggesting a mixed interfacial activation/ionic exchange immobilization. The enzyme activity and specificity (using p-nitrophenyl propionate, triacetin and both isomers of methyl mandelate) greatly depended on the support. In many instances the enzymes immobilized on the new supports offered higher activities and enantiospecificity in the hydrolysis of both enantiomers of methyl mandelate (mainly using CALB). This was coupled to a lower enzyme stability using the new supports, even in the presence of high ionic strength, suggesting that the amphipathic could be responsible of the enzyme lower stability. Using CALB, it was possible to detect a higher exposition of the enzyme Trp groups to the medium by florescence spectra after its immobilization on the amino-alkyl-supports, correlating to the higher activity and lower stability results.

Enzyme loading in the support and medium composition during immobilization alter activity, specificity and stability of octyl agarose-immobilized Eversa Transform

Eversa Transform (ETL) was immobilized on octyl agarose beads at two different enzymes loadings (1 mg/g and 15 mg/g) under 18 different conditions, including different pH values, buffers, additives (different solvents, Ca2+, NaCl). Their activity was analyzed at pH 5 and 7 with p-nitrophenyl butyrate and at pH 5 with triacetin, determining also its stability at pH 5 and 7 (in different media). Ca2+ stabilized ETL biocatalysts while phosphate destabilized them. The overloaded biocatalysts were generally less stable and with a lower specific activity than the lowly loaded biocatalyst. Results show that enzyme activity (even by a 3 fold factor) and stability of the immobilized enzyme may be tailored by controlling the immobilization conditions, but the effects of the immobilization conditions on activity depend on the substrate and conditions of activity determination, the effects on stability depend on the inactivation conditions. Moreover, the enzyme loading of the biocatalysts defines the effects of the immobilization conditions, and there are clear interactions between immobilization conditions (e.g., immobilization pH determines the effect of the presence of NaCl). These suggest that the extrapolation of the results obtained with one substrate under one condition to other conditions can lead to wrong decisions.

Magnetizing Biotech-Advances in (In Vivo) Magnetic Enzyme Immobilization

Industrial biocatalysis, a multibillion dollar industry, relies on the selectivity and efficacy of enzymes for efficient chemical transformations. However, enzymes, evolutionary adapted to mild biological conditions, often struggle in industrial processes that require harsh reaction conditions, resulting in reduced stability and activity. Enzyme immobilization, which addresses challenges such as enzyme reuse and stability, has therefore become a vital strategy for improving enzyme use in industrial applications. Traditional immobilization techniques rely on the confinement or display of enzymes within/on organic or inorganic supports, while recent advances in synthetic biology have led to the development of solely biological in vivo immobilization methods that streamline enzyme production and immobilization. These methods offer added benefits in terms of sustainability and cost efficiency. In addition, the development and use of multifunctional materials, such as magnetic (nano)materials for enzyme immobilization, has enabled improved separation and purification processes. The combination of both "worlds," opens up new avenues in both (industrial) biocatalysis, fundamental science, and biomedicine. Therefore, in this review, we provide an overview of established and recently emerging methods for the generation of magnetic protein immobilizates, placing a special focus on in vivo immobilization solutions.

Design strategies for novel esterase purification processes from Trichoderma harzianum-An insight into kinetic and thermodynamic analyses

Designing purification strategies for the fermentation derived enzymes is the most challenging task and require a thorough understanding on the physio-chemical properties of the target enzyme. The current investigation aims to establish purification strategies for a novel esterase from Trichoderma harzianum followed by their kinetic and thermodynamic analyses. The highest esterase purification fold of 6.65 was observed with the acetone-based precipitation at 60 % (v/v) saturation level among other precipitation studies. Further, using Taguchi orthogonal design, the optimal composition of an aqueous two-phase system consisting of PEG 6000 (30 % w/w), sodium citrate (15 %, w/w), sodium chloride (10 %, w/w), and pH (7.0) was obtained that resulted in the esterase purification fold of 3.93. A higher esterase purification fold of 20.47 was obtained using size exclusion chromatography technique. The optimal temperature and pH for the maximum activity of purified esterase were found to be 30 °C and 7, respectively. The thermal deactivation of esterase was followed the first order rate kinetics for the temperature range from 323 K to 353 K. The activation energy (Ea), enthalpy (ΔH), and entropy (ΔS) of thermal denaturation of esterase were estimated to be 69 (kJ/mol), 66.29 (kJ/mol), and 1.21(kJ/mol.K), respectively. The addition of solvents such as ethanol, methanol, acetone, and chloroform at 50 % (v/v) and metal ions, such as calcium chloride, sodium chloride, and zinc sulphate at 1 mM enhanced the esterase activity. Esterase had a higher affinity towards p-nitrophenyl acetate as compared to other short and long-chain fatty acid substrates as observed from the turnover number and Michaelis-Menten kinetic constants. Furthermore, the relative molecular weight of esterase was estimated around 75 kDa using native and SDS-PAGE electrophoresis.

Enhanced Stability and Reusability of Subtilisin Carlsberg Through Immobilization on Magnetic Nanoparticles

Introduction

Immobilizing enzymes on solid supports such as magnetic nanoparticles offers multi-dimensional advantages, including enhanced conformational, structural, and thermal stability for long-term storage and reusability.

Methodology

The gene encoding subtilisin Carlsberg was isolated from proteolytic Bacillus haynesii, a bacterium derived from salt mines. The nucleotide sequence encoding pro-peptide and mature protein were cloned into pET22(a)+ vector and expressed in E. coli. The extracted enzyme was subsequently immobilized on glutaraldehyde-linked-chitosan-coated magnetic nanoparticles.

Results

Fourier-transform infrared analysis revealed higher intensity peaks for the enzyme-immobilized nanoparticles indicating an increase in bonding numbers. X-ray diffraction analysis revealed a mild amorphous state for immobilized nanoparticles in contrast to a more crystalline state for free nanoparticles. An increased mass content and atomic percentage for carbon and nitrogen were recorded in EDX analysis for enzyme immobilized magnetic nanoparticles. Dynamic light scattering analysis showed an increase in average particle size from ~85 nm to ~250 nm. Upon enzyme immobilization, the Michaelis-Menten value increased from 11.5 mm to 15.02 mM, while the maximum velocity increased from 13 mm/min to 22.7 mm/min. Immobilization significantly improved the thermostability with 75% activity retained by immobilized enzyme at 70 °C compared to 50% activity by free enzyme at the same temperature. Immobilization yield, efficiency and activity recovery were 61%, 84% and 51%, respectively. The immobilized enzyme retained 70% of its activity after 10 cycles of reuse, and it maintained 55% of its activity compared to 50% activity by free enzyme after 30 days of storage.

Conclusion

The present study highlights the efficacy of magnetic nanoparticle-based immobilization in enhancing enzyme functioning and facilitates its incorporation into commercial applications necessitating high stability and reusability, including detergents, medicines, and bioremediation.

Immobilization of soybean peroxidase enzyme on hierarchical zeolite-ordered mesoporous carbon nanocomposite and its activity

Immobilization of enzymes on inorganic supports such as silica and carbon materials is an effective approach for chemical surface modification. In this work, hierarchical zeolite (HZ-SAPO's) materials were fabricated by a modified method, and mesoporous carbon (CMK-3) was synthesized using the SBA-15 mesoporous silica as a template. A variety of biocatalysts was prepared using HZ-SAPO with CMK to furnish the nanocomposite biocatalyst. The functionalization of amine group with APTES was done which was further immobilized by Soybean Peroxidase (SBP) enzyme. The material was subjected to a comprehensive characterization process utilizing numerous systematic methods, including X-ray diffraction, N2 adsorption-desorption isotherms, Raman spectroscopy, scanning electron microscopy, high-resolution transmittance electron microscopy, and attenuated total reflectance Fourier transform infrared spectroscopy. The pH effect on the immobilized enzyme was examined and compared to that of SBP. Further, the assessment of repeated usability of immobilized SBP with successive cycles was carried out.

A Comprehensive Guide to Enzyme Immobilization: All You Need to Know

Enzyme immobilization plays a critical role in enhancing the efficiency and sustainability of biocatalysis, addressing key challenges such as limited enzyme stability, short shelf life, and difficulties in recovery and recycling, which are pivotal for green chemistry and industrial applications. Classical approaches, including adsorption, entrapment, encapsulation, and covalent bonding, as well as advanced site-specific methods that integrate enzyme engineering and bio-orthogonal chemistry, were discussed. These techniques enable precise control over enzyme orientation and interaction with carriers, optimizing catalytic activity and reusability. Key findings highlight the impact of immobilization on improving enzyme performance under various operational conditions and its role in reducing process costs through enhanced stability and recyclability. The review presents numerous practical applications of immobilized enzymes, including their use in the pharmaceutical industry for drug synthesis, in the food sector for dairy processing, and in environmental biotechnology for wastewater treatment and dye degradation. Despite the significant advantages, challenges such as activity loss due to conformational changes and mass transfer limitations remain, necessitating tailored immobilization protocols for specific applications. The integration of immobilization with modern biotechnological advancements, such as site-directed mutagenesis and recombinant DNA technology, offers a promising pathway for developing robust, efficient, and sustainable biocatalytic systems. This comprehensive guide aims to support researchers and industries in selecting and optimizing immobilization techniques for diverse applications in pharmaceuticals, food processing, and fine chemicals.

Structure-guided design of a Zbasic2-mediated dual-enzyme nanoreactor for chiral amine synthesis

The synthesis of chiral amines is of critical importance but still challenging. Here, we present a self-sufficient and reusable dual-enzyme nanoreactor for chiral amine synthesis, featuring Zbasic2-mediated site-specific immobilization of amine dehydrogenase (AmDH) and glucose dehydrogenase (GDH) onto mesoporous silica nanoflowers (MSN). Molecular dynamics simulations revealed that the Zbasic2 tag was bound to MSN via electrostatic interactions, thus maintaining the fusion enzyme's active pocket accessibility and improving its catalytic performance. Using the Zbasic2 tags, AmDH and GDH were purified and immobilized on MSN in a one-pot process, thus creating the dual-enzyme nanoreactor. The dual-enzyme system exhibited remarkable activity and reusability, achieving high yields of 76-99 % (ee > 99 %) for various chiral amines at a substrate concentration of 400 mM and retaining a yield of 65 % after 10 cycles. This Zbasic2-based platform offers a robust and scalable strategy for sustainable chiral amine synthesis.

Surface engineering of amine transaminases to control their region-selective immobilization

The industrial use of enzymes often requires their immobilization to facilitate downstream processing and enable reuse. However, controlling enzyme orientation during immobilization is challenging and typically restricted to the N- and C-terminal regions. In this work, we propose a strategy to immobilize more active and stable amine transaminases (ATAs) by combining protein engineering with immobilization techniques. Our approach involves the structure-guided insertion of histidine clusters (His-clusters) at flexible regions of ATA subunit interfaces, enabling immobilization on cobalt-chelated carriers. By screening multiple ATAs from various microbial sources and testing different His-clusters for each, we identified the most active and stable heterogeneous biocatalysts. Notably, the immobilized H2A variant of Chromobacterium violaceum ATA (CvATA-2HA) exhibited the highest activity per mass of biocatalyst (4 U g-1). Meanwhile, the H3 variant of Pseudomonas fluorescens ATA (PfATA-H3) showed enhanced thermostability and DMSO resistance, being approximately 2.5 times more stable than its free counterpart. Overall, our findings highlight the impact of enzyme surface engineering on immobilization efficiency. The strategic placement of His-clusters enabled region-directed immobilization, improving both the activity and stability of specific ATA variants.

Exploring Enzyme Encapsulation Efficiency in MOFs Using Eco-Friendly Approaches

The encapsulation of protein enzymes in metal-organic frameworks (MOFs) has been recognized as an effective enzyme immobilization approach. In this study, we demonstrated the influence of enzyme amount and the isoelectric points (pI) of different enzymes on the enzyme loading capacity in both mechanochemical (ball-milling) and water-based approaches. We found that increasing enzyme amounts enhances MOF enzyme loading without compromising activity, while the MOF shell protects encapsulated enzymes from proteinase K degradation through its size-sheltering mechanism. However, an excess of enzymes can hinder the formation of ZIF-90. Moreover, enzymes with low pI values (e. g., catalase, pI 5.4) facilitate encapsulation in MOFs, whereas enzymes with high pI values (e. g., lysozyme, pI 11.35) are more challenging to encapsulate. The simulation results revealed that increasing the enzyme amounts and pI values raises the activation energy necessary for MOF formation. This study highlights the crucial role of enzyme properties in the encapsulation process within MOFs, providing valuable insights for fabricating enzyme-MOF biocomposites for diverse applications, such as protein drug delivery.

Polysaccharides-Directed Biomineralization of Enzymes in Hierarchical Zeolite Imidazolate Frameworks for Electrochemical Detection of Phenols

Biomineralization of enzymes inside rigid metal-organic frameworks (MOFs) is appealing due to its biocompatibility and simplicity. However, this strategy has hitherto been limited to microporous MOFs, leading to low apparent enzymatic activity. In this study, polysaccharide sodium alginate is introduced during the biomineralization of enzymes in zeolitic imidazolate frameworks (ZIFs) to competitively coordinate with metal ions, which endows the encapsulated enzyme with a 7-fold higher activity than that in microporous ZIFs. Mechanism investigation showed that the introduction of alginate generates hierarchical porous structures and enhances the hydrophilicity, which contributes to the enhanced activity of the enzyme. Moreover, the porous ZIFs protect the embedded tyrosinase under detrimental conditions, which allows for the fast detection of phenol, with the limit of detection of 0.03 mM (S/N = 3). Engineering the enzyme with MOFs to enhance its activity and stability is anticipated to extend its application in biocatalysis and biosensors.

Innovative approaches for enzyme immobilization in milk processing: advancements and industrial applications

The dairy industry is progressively integrating advanced enzyme technologies to optimize processing efficiency and elevate product quality. Among these technologies, enzyme immobilization has emerged as a pivotal innovation, offering considerable benefits in terms of enzyme reusability, stability, and overall process sustainability. This review paper explores the latest improvements in enzyme immobilization techniques and their industrial applications within milk processing. It examines various immobilization strategies, including adsorption, affinity binding, ionic and covalent binding, entrapment, encapsulation, and cross-linking, highlighting their effectiveness in improving the performance of key enzymes such as lactases, lipases, proteases and transglutaminases. The paper also delves into the economic and ecological benefits of enzyme immobilization, emphasizing its role in reducing production costs and environmental impact while maintaining or enhancing the quality of dairy products. By analyzing current trends and technological developments, this review provides a comprehensive overview of how innovative enzyme immobilization approaches are transforming milk processing. It concludes with a discussion on future research directions and potential industrial applications, underscoring the importance of continued innovation in this field to meet the increasing demands of the global dairy market.

Single-Electron Oxidation Triggered by Visible-Light-Excited Enzymes for Asymmetric Biocatalysis

By integrating enzymatic catalysis with photocatalysis, photoenzymatic catalysis emerges as a powerful strategy to enhance enzyme catalytic capabilities and provide superior stereocontrol in reactions involving reactive intermediates. Repurposing naturally occurring enzymes using visible light is among the most active directions of photoenzymatic catalysis. This Minireview focuses on a cutting-edge strategy in this direction, namely single-electron-oxidation-triggered non-natural biotransformations catalyzed by photoexcited enzymes. These straightforward transformations feature a unique radical mechanism initiated by single-electron oxidation, achieving redox-neutral non-natural C-C, C-O, and C-S bond formation, and expanding the chemical toolbox of enzymes. By highlighting recent advances in this field and emphasizing their catalytic mechanisms and synthetic potential, innovative approaches for photobiomanufacturing are anticipated.

Various Options for Covalent Immobilization of Cysteine Proteases-Ficin, Papain, Bromelain

This study explores various methods for the covalent immobilization of cysteine proteases (ficin, papain, and bromelain). Covalent immobilization involves the formation of covalent bonds between the enzyme and a carrier or between enzyme molecules themselves without a carrier using a crosslinking agent. This process enhances the stability of the enzyme and allows for the creation of preparations with specific and controlled properties. The objective of this study is to evaluate the impact of covalent immobilization under different conditions on the proteolytic activity of the enzymes. The most favorable results were achieved by immobilizing ficin and bromelain through covalent bonding to medium and high molecular weight chitosans, using 5 and 3.33% glutaraldehyde solutions, respectively. For papain, 5 and 6.67% glutaraldehyde solutions proved to be more effective as crosslinking agents. These findings indicate that covalent immobilization can enhance the performance of these enzymes as biocatalysts, with potential applications in various biotechnological fields.

ADP-ribosyltransferase-based biocatalysis of nonhydrolyzable NAD+ analogs

Enzyme promiscuity is the ability of an enzyme to catalyze an unexpected side reaction in addition to its main reaction. Here, we describe a biocatalytic process to produce nonhydrolyzable NAD+ analogs based on the ADP-ribosyltransferase activity of pertussis toxin PtxS1 subunit. First, in identical manner to normal catalysis, PtxS1 activates NAD+ to form the reactive oxocarbenium cation. Subsequently, the electrophilic ribose 1' carbon of the oxocarbenium cation is subject of an attack by the nitrogen atom of an amino group coupled to nicotinamide mimicking compounds. The nitrogen atom acts as the nucleophile instead of the natural sulfur atom substrate of the human Gαi protein. The invention builds on structural data indicating the presence of an NAD+ analog, benzamide amino adenine dinucleotide, at the NAD+ binding site of PtxS1. This was witnessed upon cocrystallization of PtxS1 with NAD+ and 3-aminobenzamide (3-AB). A pharmacophore-based screening on 3-AB followed by quantum mechanical simulations identified analogs of 3-AB with capacity to react with the oxocarbenium cation. Based on HPLC and mass spectrometry, we confirmed the formation of benzamide amino adenine dinucleotide by PtxS1, and also identified two new chemical entities. We name the new entities as isoindolone amine adenine dinucleotide, and isoquinolinone amine adenine dinucleotide, the latter being a highly fluorescent compound. The new NAD+ analogs emerge as valuable tools to study the structural biology and enzymology of NAD+ binding and consuming enzymes, such as human poly(ADP-ribose) polymerases and bacterial ADP-ribosyltransferase exotoxins, and to advance the ongoing drug development efforts.

The activity regulation of lipase from Aspergillus fumigatus by ligand through allosteric exploration

Lipase activity from Aspergillus fumigatus (AFL) were modulated by an effector (HMD) that was discovered for an allosteric site on the bioactive macromolecule. Experimental evaluation and computational modeling of allosteric effects revealed alterations in the structure of AFL. It was found that AFL's activity in HMD solution increased by approximately 46 % due to mainly enhanced lid flexibility. HMD-AFL interaction was driven by enthalpy and entropy. However, when AFL was coupled to HMD-modified microspheres (PS-HMD-p), its hydrolysis activity decreased by ∼14.3 % due to reduced lid flexibility. After immobilization, AFL's ester-synthesis activity also decreased, due to changes in the conformational dynamics and the geometric characteristics of active site. Investigating the structural dynamics of allosteric regulation of the lipase not only reveals its structural changes underlying the functional variation but also enhances the understanding of the allosteric property that is underappreciated in exoenzymes.

Unveiling the spatial rearrangements of exhausted immobilised multi-enzyme systems through cryo-X-ray fluorescence nanoprobe imaging

Enzyme immobilisation is of great importance for the fabrication of heterogeneous biocatalysts, as it allows the stabilisation of proteins using a solid support. Moreover, it permits their reuse in continuous and discontinuous reactors. The behaviour of enzymes at the interface with the materials where they are supported is not well understood during operational conditions. Here, we use X-ray fluorescence (XRF) imaging to study the changes in the overall structure of a heterogeneous biocatalyst formed by two unmodified metalloenzymes (a copper-dependent laccase and a zinc-dependent dehydrogenase) upon incubation, either under drastic (high temperature) or operational conditions. Those two enzymes were co-immobilised reversibly (by electrostatic interactions and His-tag metal coordination) to form a cascade reaction that catalyses the NAD+-dependent oxidation of diols coupled to a laccase-mediator for the in situ regeneration of the redox cofactor. Both the protein scaffolds and the metal cofactors undergo rearrangements during operational use or thermal incubation, but they seem to move as a whole unit within the support. Migration inside the support apparently causes only small alterations to the structure of the protein, yet it leads to the exhaustion of the heterogeneous biocatalyst. As such, we show that the use of advanced X-ray spectroscopy with spatial resolution can help obtain a better understanding of the molecular phenomena that occur during the operation of heterogeneous biocatalysts. Overall, this is fundamental to guide the optimisation for more productive and robust bioprocesses based on immobilised enzyme systems.

Changes in ficin specificity by different substrate proteins promoted by enzyme immobilization

Ficin extract has been immobilized using different supports: glyoxyl and Aspartic/1,6 hexamethylenediamine (Asp/HA) agarose beads. The latter was later submitted to glutaraldehyde modification to get covalent immobilization. The activities of these 3 kinds of biocatalysts were compared utilizing 4 different substrates, casein, hemoglobin and bovine serum albumin and benzoyl-arginine-p-nitroanilide at pH 7 and 5. Using glyoxyl-agarose, the effect of enzyme-support reaction time on the activity versus the four substrates at both pH values was studied. Reaction time has been shown to distort the enzyme due to an increase in the number of covalent support-enzyme bonds. Surprisingly, for all the substrates and conditions the prolongation of the enzyme-support reaction did not imply a decrease in enzyme activity. Using the Asp/HA supports (with different amount of HA) differences in the effect on enzyme activity versus the different substrates are much more significant, while with some substrates the immobilization produced a decrease in enzyme activity, with in other cases the activity increased. These different effects are even increased after glutaraldehyde treatment. That way, the conformational changes induced by the biocatalyst immobilization or the chemical modification fully altered the enzyme protein specificity. This may also have some implications when following enzyme inactivation.

Immobilization of Naringinase onto Polydopamine-Coated Magnetic Iron Oxide Nanoparticles for Juice Debittering Applications

Chemical amination of the enzyme was demonstrated to favor immobilization onto polydopamine (PDA)-coated magnetic nanoparticles (MNPs) for the first time, to the best of the author's knowledge. MNPs prepared via hydrothermal synthesis were coated with PDA for the immobilization of naringinase. X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy showed that the MNPs were composed mainly of Fe3O4 with an average size of 38.9 nm, and coated with a 15.1 nm PDA layer. Although the specific activities of α-L-rhamnosidase (RAM) and β-D-glucosidase (GLU) of free naringinase decreased with amination, the immobilization yields of the aminated enzyme increased by more than 40% for RAM and more than 10-fold for GLU. The immobilization improved the enzyme's thermal stability (at 50 °C), reaching a half-life of 40.7 and 23.1 h for RAM and GLU activities, respectively. The biocatalyst was successfully used for the debittering of grapefruit juice, detecting a reduction in naringin of 56% after 24 h. These results demonstrate that the enzyme amination is an effective strategy to enhance the immobilization on a PDA coating and could be applied to other enzymes in order to obtain an easily recoverable biocatalyst using a simple immobilization methodology.

Designing tailor-made steric matters to improve the immobilized ficin specificity for small versus large proteins

The development of strategies that can permit to adjust the size specificity of immobilized proteases by the generation of steric hindrances may enlarge its applicability. Using as a model ficin immobilized on glyoxyl agarose, two strategies were assayed to generate tailor made steric hindrances. First, ficin has been coimmobilized on supports coated with large proteins (hemoglobin or bovine serum albumin (BSA)). While coimmobilization of ficin with BSA presented no effect on the activity versus any of the assayed substrates, coimmobilization with hemoglobin permitted to improve the immobilized ficin specificity for casein versus hemoglobin, but still significant activity versus hemoglobin remained. Second, aldehyde-dextran has been employed to modify the immobilized ficin, trying to generate steric hindrances to avoid the entry of large proteins (hemoglobin) while enabling the entry of small ones (casein). This also increased the size specificity of ficin, but still did not suppress the activity versus hemoglobin. The combination of both strategies and the use of 37ºC during the proteolysis enabled to almost fully nullify the hydrolytic activity versus hemoglobin while preserving a high percentage of the activity versus casein. The modifications improved enzyme stability and the biocatalyst could be reused for 5 cycles without alteration of its properties.

Design of a Genetically Programmable and Customizable Protein Scaffolding System for the Hierarchical Assembly of Robust, Functional Macroscale Materials

Inspired by the properties of natural protein-based biomaterials, protein nanomaterials are increasingly designed with natural or engineered peptides or with protein building blocks. Few examples describe the design of functional protein-based materials for biotechnological applications that can be readily manufactured, are amenable to functionalization, and exhibit robust assembly properties for macroscale material formation. Here, we designed a protein-scaffolding system that self-assembles into robust, macroscale materials suitable for in vitro cell-free applications. By controlling the coexpression in Escherichia coli of self-assembling scaffold building blocks with and without modifications for covalent attachment of cross-linking cargo proteins, hybrid scaffolds with spatially organized conjugation sites are overproduced that can be readily isolated. Cargo proteins, including enzymes, are rapidly cross-linked onto scaffolds for the formation of functional materials. We show that these materials can be used for the in vitro operation of a coimmobilized two-enzyme reaction and that the protein material can be recovered and reused. We believe that this work will provide a versatile platform for the design and scalable production of functional materials with customizable properties and the robustness required for biotechnological applications.

Keeping the Distance: Activity Control in Solid-Supported Sucrose Phosphorylase by a Rigid α-Helical Linker of Tunable Spacer Length

Enzyme immobilization into carrier materials has broad importance in biotechnology, yet understanding the catalysis of enzymes bound to solid surfaces remains challenging. Here, we explore surface effects on the catalysis of sucrose phosphorylase through a fusion protein approach. We immobilize the enzyme via a structurally rigid α-helical linker [EA3K] n of tunable spacer length due to the variable number of pentapeptide repeats used (n = 6, 14, 19). Molecular modeling and simulation approaches delineate the conformational space sampled by each linker relative to its His-tag cap used for surface tethering. The population distribution of linker conformers gets broader, with a consequent shift of the enzyme-to-surface distance to larger values (≤15 nm), as the spacer length increases. Based on temperature kinetic studies, we obtain an energetic description of catalysis by the enzyme-to-linker fusions in solution and immobilize on Ni2+-chelate agarose. The solid-supported enzymes involve distinct changes in enthalpy-entropy partitioning within the frame of invariant Gibbs free energy of activation (ΔG ‡ = ∼61 kJ/mol at 30 °C). The entropic contribution (-TΔS ‡) to ΔG ‡ increases with the spacer length, from -16.4 kJ/mol in the linker-free enzyme to +7.9 kJ/mol in the [EA3K]19 linked fusion. The immobilized [EA3K]19 fusion protein is indistinguishable in its catalytic properties from the enzymes in solution, which behave identically regardless of their linker. Enzymes positioned closer to the surface arguably experience a higher degree of molecular organization ("rigidification") that must relax for catalysis through the additional uptake of heat, compensated by a gain in entropy. Increased thermostability of these enzymes (up to 2.8-fold) is consistent with the proposed rigidification effect. Collectively, our study reveals surface effects on the activation parameters of sucrose phosphorylase catalysis and shows their consistent dependence on the length of the surface-tethering linker. The fundamental insight here obtained, together with the successful extension of the principle to a different enzyme (nigerose phosphorylase), suggests that rigid linker-based control of the protein-surface distance can be used as an engineering strategy to optimize the activity characteristics of immobilized enzymes.

Novel Hybrid Catalysts of Cysteine Proteases Enhanced by Chitosan and Carboxymethyl Chitosan Micro- and Nanoparticles

Micro- and nanoparticles of chitosan and carboxymethyl chitosan were synthesized, both with and without ascorbic acid. Methods were developed to form complexes between these micro- and nanoparticles and plant proteases-ficin, papain, and bromelain. It was demonstrated that the activity of cysteine protease complexes with carboxymethyl chitosan micro- and nanoparticles was higher compared to those with chitosan micro- and nanoparticles. Additionally, the complexes of ficin, papain, and bromelain with chitosan and carboxymethyl chitosan micro- and nanoparticles synthesized in the presence of ascorbic acid exhibited greater proteolytic activity than those formed with particles prepared without ascorbic acid. Molecular docking studies revealed that the amino acid residues of ficin, papain, and bromelain primarily interact with chitosan and carboxymethyl chitosan through hydrogen bonding and hydrophobic interactions. The amino acid residues in the active sites of these enzymes participate in a complex formation, which likely contributes to the increased activity and stability of cysteine proteases in complexes with chitosan and carboxymethyl chitosan micro- and nanoparticles.

Macrophage proteomic analysis of covalent immobilization of hyaluronic acid and graphene oxide on CoCr alloy in a tribocorrosive environment

In this work, a sequential covalent immobilization of graphene oxide (GO) and hyaluronic acid (HA) is performed to obtain a biocompatible wear-resistant nanocoating on the surface of the biomedical grade cobalt-chrome (CoCr) alloy. Nanocoated CoCr surfaces were characterized by Raman spectroscopy and electrochemical impedance spectroscopy (EIS) in 3 g/L HA electrolyte. Tribocorrosion tests of the nanocoated CoCr surfaces were carried out in a pin on flat tribometer. The biological response of covalently HA/GO biofunctionalized CoCr surfaces with and without wear-corrosion processes was studied through the analysis of the proteome of macrophages. Raman spectra revealed characteristic bands of GO and HA on the functionalized CoCr surfaces. The electrochemical response by EIS showed a stable and protective behavior over 23 days in the simulated biological environment. HA/GO covalently immobilized on CoCr alloy is able to protect the surface and reduce the wear volume released under tribocorrosion tests. Unsupervised classification analysis of the macrophage proteome via hierarchical clustering and principal component analysis (PCA) revealed that the covalent functionalization on CoCr enhances the macrophage biocompatibility in vitro. On the other hand, disruption of the HA/GO nanocoating by tribocorrosion processes induced a macrophage proteome which was differently clustered and was distantly located in the PCA space. In addition, tribocorrosion induced an increase in the percentage of upregulated and downregulated proteins in the macrophage proteome, revealing that disruption of the covalent nanocoating impacts the macrophage proteome. Although macrophage inflammation induced by tribocorrosion of HA/GO/CoCr surfaces is observed, it is ameliorated by the covalently grafting of HA, which provides immunomodulation by eliciting downregulations in characteristic pro-inflammatory signaling involved in inflammation and aseptic loosening of CoCr joint arthroplasties. Covalent HA/GO nanocoating on CoCr provides potential applications for in vivo joint prostheses led a reduced metal-induced inflammation and degradation by wear-corrosion.

Enhanced Interfacial Electron Transfer in Photocatalyst-Natural Enzyme Coupled Artificial Photosynthesis System: Tuning Strategies and Molecular Simulations

Laccase is capable of catalyzing a vast array of reactions, but its low redox potential limits its potential applications. The use of photocatalytic materials offers a solution to this problem by converting absorbed visible light into electrons to facilitate enzyme catalysis. Herein, MIL-53(Fe) and NH2-MIL-53(Fe) serve as both light absorbers and enzyme immobilization carriers, and laccase is employed for solar-driven chemical conversion. Electron spin resonance spectroscopy results confirm that visible light irradiation causes rapid transfer of photogenerated electrons from MOF excitation to T1 Cu(II) of laccase, significantly increasing the degradation rate constant of tetracycline (TC) from 0.0062 to 0.0127 min-1. Conversely, there is only minimal or no electron transfer between MOF and laccase in the physical mixture state. Theoretical calculations demonstrate that the immobilization of laccase's active site and its covalent binding to the metal-organic framework surface augment the coupled system's activity, reducing the active site accessible from 27.8 to 18.1 Å. The constructed photo-enzyme coupled system successfully combines enzyme catalysis' selectivity with photocatalysis's high reactivity, providing a promising solution for solar energy use.

An insight into heat stress response and adaptive mechanism in cotton

The growing worldwide population is driving up demand for cotton fibers, but production is hampered by unpredictable temperature rises caused by shifting climatic conditions. Numerous research based on breeding and genomics have been conducted to increase the production of cotton in environments with high and low-temperature stress. High temperature (HT) is a major environmental stressor with global consequences, influencing several aspects of cotton plant growth and metabolism. Heat stress-induced physiological and biochemical changes are research topics, and molecular techniques are used to improve cotton plants' heat tolerance. To preserve internal balance, heat stress activates various stress-responsive processes, including repairing damaged proteins and membranes, through various molecular networks. Recent research has investigated the diverse reactions of cotton cultivars to temperature stress, indicating that cotton plant adaptation mechanisms include the accumulation of sugars, proline, phenolics, flavonoids, and heat shock proteins. To overcome the obstacles caused by heat stress, it is crucial to develop and choose heat-tolerant cotton cultivars. Food security and sustainable agriculture depend on the application of genetic, agronomic, and, biotechnological methods to lessen the impacts of heat stress on cotton crops. Cotton producers and the textile industry both benefit from increased heat tolerance. Future studies should examine the developmental responses of cotton at different growth stages, emphasize the significance of breeding heat-tolerant cultivars, and assess the biochemical, physiological, and molecular pathways involved in seed germination under high temperatures. In a nutshell, a concentrated effort is required to raise cotton's heat tolerance due to the rising global temperatures and the rise in the frequency of extreme weather occurrences. Furthermore, emerging advances in sequencing technologies have made major progress toward successfully se sequencing the complex cotton genome.

Lignin: The green powerhouse for enzyme immobilization in biocatalysis and biosensing

Enzymes play an important role in diverse industries and are critical components of many industrial products, yet, their application is limited due to their sensitivity to environmental conditions, recovery challenges, and susceptibility to inhibition. Immobilizing enzymes onto a suitable support matrix imparts higher resistance and improves operational flexibility, recyclability, and reusability. Lignin, a renewable and abundant biopolymer derived from the paper and pulp industry, has emerged as one of the prominent materials to be incorporated in support matrices. The distinctive characteristics of lignin include high mechanical strength, ease of separation, chemical stability, robust matrix for securing enzyme binding, biocompatibility, and ease of surface functionalization, making it a promising alternative to traditional synthetic materials. Research studies suggest the effectiveness of various lignin-based materials for immobilizing enzymes and significantly improving their stability, reusability, and catalytic activity. This article critically examines the unique properties of lignin and highlights significant contributions made in the development of enzyme immobilization for biocatalysis and biosensing applications. Additionally, the roles of hybrid materials, multienzyme immobilization, and innovative strategies like interfacial activation and enzyme shielding are discussed for overcoming the current challenges and developing sustainable, efficient, and robust biocatalytic and biosensing processes for industrial applications.

In-situ stabilized lipase in calcium carbonate microparticles for activation in solvent-free transesterification for biodiesel production

Biodiesel serves as a crucial biofuel alternative to petroleum-based diesel fuels, achieved through enzymatic transesterification of oil substrates. This study aims to investigate stabilized lipase (LP) within calcium carbonate (CaCO3) microparticles as a catalyst for solvent-free transesterification in biodiesel synthesis. The specific hydrolysis activity of the in-situ immobilized LP was 66% of that of free LP. However, the specific transesterification activity of immobilized LP in the solvent-free phase for biodiesel production was 2.29 times higher than that of free LP. These results suggest that the interfacial activation of LP molecules is facilitated by the inorganic CaCO3 environment. The immobilized LP demonstrated higher biodiesel production levels with superior stability compared to free LP, particularly regarding methanol molar ratio and temperature. To the best of our knowledge, there are no previous reports on the in-situ immobilization of LP in a CaCO3 carrier without any crosslinker as an interfacial-activated biocatalyst for biodiesel production.

Optimizing the activation of agarose beads with divinyl sulfone for enzyme immobilization and stabilization

The focus of the present work is to find the optimal conditions for the activation of agarose beads with divinyl sulfone (DVS). The reactivity of the vinyl sulfone groups in the support was checked by the support capacity to react with ethylamine; via elemental analysis. In addition, trypsin was used as a model enzyme to test the immobilization and stabilization capabilities of the different supports. The higher the pH, the more vinyl sulfone groups are incorporated into the support, but lower reactivity versus ethylamine is observed. Too long activation times led to similar results. A N/S ratio of 1 means that all vinyl sulfone groups were reactive, and it was always lower than tis figure. The N in the support was 50 % of the amount observed for glyoxyl supports activated with ethylenediamine, suggesting the VS polymerization may be a likely explanation for this result. The higher N/S ratio in the support (modified with ethylamine), the higher the obtained stabilization, very likely by the lower polymerization of the vinyl sulfone on the support. We propose 360 mM divinyl sulfone, at pH 11.5 and 2 h as optimal conditions to reach the highest enzyme stabilization by immobilization in this support.

Enhancing rhamnolipid production via immobilized Pseudomonas stutzeri lipase: A comparative study

Rhamnolipids (RLs) are widely studied biosurfactants with significant industrial potential in cosmetics, pharmaceuticals, and bioremediation due to their excellent surface activity, emulsifying properties and bioactive characteristics. However, high production costs impede their mass production. This study investigates the immobilization of Pseudomonas stutzeri lipase (PSL) on various supports to enhance RL synthesis efficiency, focusing on yield and regioselectivity in the enzymatic synthesis of 4-O-lauroylrhamnose by the transesterification of rhamnose with vinyl laurate. Three immobilization methods were compared: covalent binding, adsorption on Celite, and adsorption on hydrophobic supports. The immobilization efficiency varied depending on the method used, with the lowest observed for adsorption on Celite (56 %), followed by covalent immobilization on Sepabeads (EC-EP/S 78 % and EC-EP/L 70 %), and the highest for adsorption on hydrophobic supports (83-97 %, with EC-OD being the best at 97 %). For the enzymatic synthesis of 4-O-lauroylrhamnose, covalent immobilization on Sepabeads™ EC-EP yielded low conversions due to restricted conformational freedom of the enzyme. Celite® 545 adsorption resulted in moderate conversion rates, limited by the electrostatic interactions restricting enzyme activity. The most promising results were obtained with hydrophobic supports, particularly Purolite® ECR8806F, achieving nearly complete conversion and maintaining high regioselectivity at the 4-position of rhamnose in both THF and the green solvent 2-methyltetrahydrofuran (2-MeTHF). The study highlights the critical role of support hydrophobicity and active surface area in the immobilized enzyme performance. PSL immobilized on Purolite® ECR8806F demonstrated significant potential for sustainable RLs production, showing excellent reusability, stability and productivity across multiple reaction cycles. This study presents a significant advancement in RLs production by optimizing PSL immobilization and reaction conditions, facilitating the way for more cost-effective and sustainable industrial applications.

Bioconjugation of Serratiopeptidase with Titanium Oxide Nanoparticles: Improving Stability and Antibacterial Properties

Antimicrobial resistance (AMR) poses a significant global health threat, necessitating the development of novel antibacterial strategies. Serratiopeptidase (SP), a metalloprotease produced by bacteria such as Serratia marcescens, has gained attention not only for its anti-inflammatory properties but also for its potential antibacterial activity. However, its protein nature makes it susceptible to pH changes and self-proteolysis, limiting its effectiveness. This study aimed to increase both the enzymatic stability and antibacterial activity of serratiopeptidase through immobilization on titanium oxide nanoparticles (TiO2-NPs), leveraging the biocompatibility and stability of these nanomaterials. Commercial TiO2-NPs were characterized using TGA/DTG, FT-IR, UV-Vis, and XRD analyses, and their biocompatibility was assessed through cytotoxicity studies. Serratiopeptidase was produced via fermentation using the C8 isolate of Serratia marcescens obtained from the intestine of Bombyx mori L., purified chromatographically, and immobilized on carboxylated nanoparticles via EDC/NHS coupling at various pH conditions. The optimal enzymatic activity was achieved by using pH 5.1 for nanoparticle activation and pH 5.5 for enzyme coupling. The resulting bioconjugate demonstrated stable proteolytic activity at 25 °C for 48 h. Immobilization was confirmed by FT-IR spectroscopy, and the Michaelis-Menten kinetics were determined. Notably, the bioconjugate exhibited two-fold greater antibacterial activity against E. coli than the free enzyme or TiO2-NPs at 1000 µg/mL. This study successfully developed a serratiopeptidase-TiO2 bioconjugate with enhanced enzymatic stability and antibacterial properties. The improved antibacterial activity of the immobilized enzyme presents a promising approach for developing new tools to combat antimicrobial resistance, with potential applications in healthcare, food safety, and environmental protection.

Production of γ-aminobutyric acid by immobilization of two Yarrowia lipolytica glutamate decarboxylases on electrospun nanofibrous membrane

This study harnesses glutamate decarboxylase (GAD) from Yarrowia lipolytica to improve the biosynthesis of γ-aminobutyric acid (GABA), focusing on boosting the enzyme's catalytic efficiency and stability by immobilizing it on nanofibrous membranes. Through recombinant DNA techniques, two GAD genes, YlGAD1 and YlGAD2, were cloned from Yarrowia lipolytica and then expressed in Escherichia coli. Compared to their soluble forms, the immobilized enzymes exhibited significant improvements in thermal and pH stability and increased resistance to chemical denaturants. The immobilization notably enhanced substrate affinity, as evidenced by reduced Km values and increased kcat values, indicating heightened catalytic efficiency. Additionally, the immobilized YlGAD1 and YlGAD2 enzymes showed substantial reusability, maintaining 50% and 40% of their activity, respectively, after six consecutive cycles. These results underscore the feasibility of employing immobilized YlGAD enzymes for cost-effective and environmentally sustainable GABA production. This investigation not only affirms the utility of YlGADs in GABA synthesis but also underscores the advantages of enzyme immobilization in industrial settings, paving the way for scalable biotechnological processes.

Tailoring the specificity of ficin versus large hemoglobin and small casein by co-immobilizing inert proteins on the immobilized enzyme layer and further modification with aldehyde dextran

Ficin has been immobilized at full loading on glyoxyl agarose beads. Then, ficin was blocked with 2,2'-dipyridyldisulfide. To be effective, the modification must be performed in the presence of 0.5 M urea, as the enzyme was not inhibited under standard conditions, very likely because the catalytic Cys was not fully exposed to the medium. Activity could be fully recovered by incubation with 1 M mercaptoethanol. This biocatalyst could hydrolyze hemoglobin and casein. The objective of this paper was to increase the enzyme specificity versus small proteins by generating steric hindrances to the access of large proteins. The step by step blocking via ionic exchange of the biocatalyst with aminated bovine serum albumin (BSA), aldehyde dextran and a second layer of aminated BSA produced a biocatalyst that maintained its activity versus small synthetic substrates, increased the biocatalyst stability, while reduced its activity to over 50 % versus casein. Interestingly, this treatment almost fully annulled the activity versus hemoglobin, more effectively at 37 °C than at 55 °C. The biocatalyst could be reused 5 times without changes in activity. The changes could be caused by steric hindrances, but it cannot be discarded some changes in enzyme sequence specificity caused by the modifications.

Amination of naringinase to improve citrus juice debittering using a catalyst immobilized on glyoxyl-agarose

A naringinase complex was chemically aminated prior to its immobilization on glyoxyl-agarose to develop a robust biocatalyst for juice debittering. The effects of amination on the optimal pH and temperature, thermal stability, and debittering performance were analyzed. Concentration of amino groups on catalysts surface increased in 36 %. Amination reduced the β-glucosidase activity of naringinase complex; however, did not affect optimal pH and temperature of the enzyme and it favored immobilization, obtaining α-l-rhamnosidase and β-d-glucosidase activities of 1.7 and 4.2 times the values obtained when the unmodified enzymes were immobilized. Amination favored the stability of the immobilized biocatalyst, retaining 100 % of both activities after 190 h at 30 °C and pH 3, while its non-aminated counterpart retained 80 and 52 % of α-rhamnosidase and β-glucosidase activities, respectively. The immobilized catalyst showed a better performance in grapefruit juice debittering, obtaining a naringin conversion of 7 times the value obtained with the non-aminated catalyst.

Hyperactivation of crosslinked lipases in elastic hydroxyapatite microgel and their properties

Effective enzyme stabilization through immobilization is essential for the functional usage of enzymatic reactions. We propose a new method for synthesizing elastic hydroxyapatite microgel (E-HAp-M) materials and immobilizing lipase using this mesoporous mineral via the ship-in-a-bottle-neck strategy. The physicochemical parameters of E-HAp-M were thoroughly studied, revealing that E-HAp-M provides efficient space for enzyme immobilization. As a model enzyme, lipase (LP) was entrapped and then cross-linked enzyme structure, preventing leaching from mesopores, resulting in highly active and stable LP/E-HAp-M composites. By comparing LP activity under different temperature and pH conditions, it was observed that the cross-linked LP exhibited improved thermal stability and pH resistance compared to the free enzyme. In addition, they demonstrated a 156% increase in catalytic activity compared with free LP in hydrolysis reactions at room temperature. The immobilized LP maintained 45% of its initial activity after 10 cycles of recycling and remained stable for over 160 days. This report presents the first demonstration of a stabilized cross-linked LP in E-HAp-M, suggesting its potential application in enzyme-catalyzed processes within biocatalysis technology.

Pros and Cons in Various Immobilization Techniques and Carriers for Enzymes

In recent years, enzyme immobilization technology has been developed, and studies on immobilized enzyme materials have become very prominent. With the immobilization technique, enzymes and compatible carrier materials are combined or enzyme crystals/aggregates are used in a carrier-free fashion, by physical, chemical, or biochemical methods. As a kind of biocatalyst, immobilized enzymes can catalyze certain chemical reactions with high selectivity and high efficiency under relatively mild reaction conditions and eliminate pollution to the environment. Considering the current status and applications of immobilized enzyme technology and materials emerging in the last 5 years, this mini-review introduces the advantages and disadvantages of various enzyme immobilization techniques with carriers as well as the pros and cons of different materials for immobilization. The future prospects of immobilization technology and carrier materials are outlined, aiming to provide a reference for further research and applications of sustainable technology.

Improved L-Asparaginase Properties and Reusability by Immobilization onto Functionalized Carbon Xerogels

Enzyme immobilization can offer a range of significant advantages, including reusability, and increased selectivity, stability, and activity. In this work, a central composite design (CCD) of experiments and response surface methodology (RSM) were used to study, for the first time, the L-asparaginase (ASNase) immobilization onto functionalized carbon xerogels (CXs). The best results were achieved using CXs obtained by hydrothermal oxidation with nitric acid and subsequent heat treatment in a nitrogen flow at 600 °C (CX-OX-600). Under the optimal conditions (81 min of contact time, pH 6.2 and 0.36 g/L of ASNase), an immobilization yield (IY) of 100 % and relative recovered activity (RRA) of 103 % were achieved. The kinetic parameters obtained also indicate a 1.25-fold increase in the affinity of ASNase towards the substrate after immobilization. Moreover, the immobilized enzyme retained 97 % of its initial activity after 6 consecutive reaction cycles. All these outcomes confirm the promising properties of functionalized CXs as support for ASNase, bringing new insights into the development of an efficient and stable immobilization platform for use in the pharmaceutical industry, food industry, and biosensors.

Catalase immobilization: Current knowledge, key insights, applications, and future prospects - A review

Catalase (CAT), a ubiquitous enzyme in all oxygen-exposed organisms, effectively decomposes hydrogen peroxide (H2O2), a harmful by-product, into water and oxygen, mitigating oxidative stress and cellular damage, safeguarding cellular organelles and tissues. Therefore, CAT plays a crucial role in maintaining cellular homeostasis and function. Owing to its pivotal role, CAT has garnered considerable interest. However, many challenges arise when used, especially in multiple practical processes. "Immobilization", a widely-used technique, can help improve enzyme properties. CAT immobilization offers numerous advantages, including enhanced stability, reusability, and facilitated downstream processing. This review presents a comprehensive overview of CAT immobilization. It starts with discussing various immobilization mechanisms, support materials, advantages, drawbacks, and factors influencing the performance of immobilized CAT. Moreover, the review explores the application of the immobilized CAT in various industries and its prospects, highlighting its essential role in diverse fields and stimulating further research and investigation. Furthermore, the review highlights some of the world's leading companies in the field of the CAT industry and their substantial potential for economic contribution. This review aims to serve as a discerning, source of information for researchers seeking a comprehensive cutting-edge overview of this rapidly evolving field and have been overwhelmed by the size of publications.

Microtiter Plate Immobilization Screening for Prototyping Heterogeneous Enzyme Cascades

Immobilization is a key enabling technology in applied biocatalysis that facilitates the separation, recovery, and reuse of heterogeneous biocatalysts. However, finding a consensus immobilization protocol for several enzymes forming a multi-enzyme system is extremely difficult and relies on a combinatorial trial-and-error approach. Herein, we describe a protocol in which 17 different carriers functionalized with different reactive groups are tested in a 96-well microtiter plate to screen up to 21 immobilization protocols for up to 18 enzymes. This screening includes an activity and stability assay to select the optimal immobilization chemistry to achieve the most active and stable heterogeneous biocatalysts. The information retrieved from the screening can be rationalized using a Python-based application CapiPy. Finally, through scoring the screening results, we find the consensus immobilization protocol to assemble an immobilized four-enzyme system to transform vinyl acetate into (S)-3-hydroxybutyric acid. This methodology opens a path to speed up the prototyping of immobilized multi-enzyme pathways for chemical manufacturing.

A self-catalyzing strategy for co-immobilization of two distinct proteins at equimolar ratio: A case study of 3A and 2C to develop a chromatographic method for finding prospective dual-target compoundsfrom complex matrices

BACKGROUND

Immobilized proteins hold promise as the basic units that have enabled a broad range of analytical applications within chemical measurement science. As yet, the co-immobilization of diverse proteins at precise ratio and whether they give rise to improved analytical performance remain challengeable. Herein, we utilized a circularly permuted HaloTag (cpHaloTag) to achieve the co-immobilization of two proteins at precise ratio, which was applied in developing a chromatographic method with improved specificity for pursuing dual-target compounds.

RESULTS

The methodology involved the fusion 3A and 2C at N- and C-terminuses of cpHaloTag, the immobilization of the fusion protein onto silica gel through bioorthogonal reaction, the morphological and functional characterization, the application in finding dual-target compounds. Expression of the fusion protein in E. coli system showed a yield of milligram level with the presence of 3A and 2C domains. Immobilization of the protein was achieved in 10 min with a reaction efficiency more than 88.5 %. Immobilized 3A-cpHalo-2C exhibited higher specificity and better retentions of canonical compounds of the two enzymes in comparison with the column containing immobilized 3A or 2C alone. In real sample application, screening analysis found that hyperoside, cymaroside, and baicalin were dual-target compounds in concert with 3A and 2C in Shuanghuanglian extract.

SIGNIFICANCE

Taking 3A and 2C as probe, we proposed a simple method for direct co-immobilization of diverse proteins from cell lysates and demonstrated an affinity chromatographic-based dual-target compound screening platform. The implications of these methodology are possible to insight the de novo design of multi-target surface for fabricating new bioanalytical methods with improved performance.

High catalytic nickel-platinum nanozyme enhancing colorimetric detection of Salmonella Typhimurium in milk

Colorimetric qualitative and sensitive quantitative detection of Salmonella Typhimurium (S. Typhimurium) holds significant importance for ensuring food safety and preventing foodborne illnesses. In the study, an ultra-high catalytic activity and biocompatible nickel-platinum nanoparticle (NiPt NP) nanozyme is successful synthesized to prepare a NLISA strategy for the detection of S. Typhimurium. The synthesized NiPt NPs exhibit high oxidase-like catalytic efficiency, with a Michaelis constant (Km) of 0.493 mM, similar to that of natural horseradish peroxidase (HRP). The maximal reaction velocity (Vmax) was determined to be 1.97 × 10-7 M·s-1 exhibiting a 1.97-fold higher than that of the HRP (1.0 × 10-7 M·s-1). Meanwhile, the antibody employed in this NiPt NPs-based NLISA exhibits exceptional capture efficacy, generating a stable immune complex with S. Typhimurium. The NiPt NPs-based NLISA demonstrates sensitivity, specificity, convenience, and cost-efficiency for the detection of S. Typhimurium. Under optimal conditions, this NiPt NPs-based NLISA demonstrates a quantitative range of 103∼106 cfu/mL with a detection limit as low as 103 cfu/mL. A single-blind experimental testing detects different concentrations of S. Typhimurium spiked skim milk, indicating the application potential of the proposed NLISA in real samples. In all, this research provides novel insights into the synthesis of nanozymes with excellent catalytic activity and their applications in S. Typhimurium biosensing.