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.

Advances, strategies, and application of immobilized lipase for aroma compound synthesis: Focus on benzyl acetate, isoamyl acetate, and ethyl valerate

Lipases, catalyzing triglyceride hydrolysis, have emerged as versatile biocatalysts for aroma compound synthesis. Aroma compounds, valued for their pleasant scents, have traditional extraction limitations like environmental challenges, low yield and high costs. Lipase-mediated biosynthesis, specially immobilized ones, offers a sustainable and green alternative. Immobilized lipases catalyze transesterification and esterification reactions to produce these compounds with improving enzyme stability, reusability, and overall better catalytic efficiency, making them an appropriate approach for industrial applications. Based on our knowledge, for the first time immobilized lipases for producing benzyl acetate, isoamyl acetate, and ethyl valerate were focused in this review. It also emphasizes how nanotechnology-based supports such as silica, magnetic nanoparticles, and smart polymers improve enzyme stability, reusability, and efficiency. By exploring various immobilization techniques and materials, the review shows how these advances make enzyme use more practical and sustainable for industrial applications. Various immobilized lipases, substrates, and reaction conditions for optimizing these aroma compounds synthesis was discussed.

Hyperbranched polymer-crosslinked laccase aggregates for efficient aerobic oxidation of alcohols

The crosslinked enzyme aggregate (CLEA) technique has been developed as an easy and convenient strategy for carrier-free immobilization of enzymes. However, the irregular voids of enzyme aggregates limit the controlled crosslinking process by using regular crosslinkers such as glutaraldehyde. To overcome this limitation, here we have developed a simple strategy for the preparation of hyperbranched polymer-crosslinked laccase aggregates (HPCLEAs). Hyperbranched polymers were generated in voids of laccase aggregates, and the in situ crosslinking through the formation of hyperbranched polymers provided access to the void-adaptive crosslinking process. These HPCLEAs had irregular shapes and sizes of ∼2-10 μm. 99 % of the initial activity was maintained under the optimized preparation conditions. Further incorporation of 2,2,6,6-tetramethyl-1-piperidine-N-oxyl (TEMPO) facilitated the proximity between laccase and TEMPO, resulting in efficient aerobic oxidation of alcohols. Additionally, these catalysts could be easily recovered and reused four times with a slight loss of activity. This strategy may open an avenue for the rational design and co-immobilization of enzyme and molecular catalysts used for chemoenzymatic catalysis.

Simulation Study of Carbonic Anhydrase Adsorption on Self-Assembled Monolayers

Carbonic anhydrase (CA) is a zinc-containing metalloenzyme that can rapidly catalyze the interconversion of CO2 and bicarbonate under suitable conditions. In industrial applications such as carbon capture, the performance of immobilized CA is highly related to its adsorption orientation and conformational changes on different carrier surfaces. In this work, the combined simulations of Parallel Tempering Monte Carlo and all-atom molecular dynamics were employed to uncover the adsorption mechanisms, orientations, and conformational changes of CA on charged self-assembled monolayers with different surface charge densities. The simulation results demonstrate that the adsorption of CA on charged surfaces is dominated by electrostatic interactions and influenced by the distribution of charged areas on the surface. CA adsorbs on the NH2-SAM surfaces with a ″bottom-on″ orientation with its active pocket facing the solution, which is beneficial for the catalytic process of CA. Asp160 was identified as a common adsorption residue for CA on NH2-SAM surfaces with different SCDs. Furthermore, the native structure of CA is well preserved after adsorption on the NH2-SAM surface, which is advantageous for the recovery of the catalytic activity of immobilized CA. In summary, this work elucidates the role of surface charge in regulating the adsorption orientation of carbonic anhydrase and its conformational changes during the adsorption process at the molecular level and provides theoretical guidance for the design of CA-based biocatalysts.

Immobilization, optimization, characterization and kinetic properties of polyphenol oxidase to multi-walled carbon nanotube

In this study, the kinetic properties of polyphenol oxidase (PPO) extracted from Satureja cuneifolia were investigated using catechol and 4-methylcatechol as substrates. Optimal pH and temperature values were determined at each purification step. Subsequently, the optimum immobilization conditions were established as 2 hours of stirring time and 0.05 g of multi-walled carbon nanotubes (MWCNTs). Characterization by BET, FTIR, DTA/TG, TEM, and SEM/EDX analyses confirmed the successful immobilization of PPO onto mesoporous MWCNTs, with notable changes in surface morphology and thermal degradation behavior. The optimum pH for the free enzyme remained constant across purification methods but varied with the substrate, while the optimum temperature was consistently found at 30 °C. Upon immobilization, the optimum temperature shifted to higher values, indicating enhanced thermal stability. Catalytic efficiency (Vmax/KM) for catechol decreased significantly after immobilization (from 2.5 × 106 to 5 × 104 min-1), whereas for 4-methylcatechol, the immobilized enzyme retained a high catalytic efficiency (Vmax/KM =1 × 106 min-1), comparable to that of the free enzyme. This shift suggests that immobilization favored substrate specificity toward 4-methylcatechol. Overall, the MWCNT-PPO system demonstrated enhanced stability, improved reusability, and altered substrate selectivity, making it a strong candidate for industrial biocatalytic applications where operational durability and efficiency are critical.

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.

Functionalization of amylopectin as a strategy to improve polyethylene terephthalate hydrolase-cross-linked enzyme aggregate (IsPETase-CLEA) in plastic degradation

Polyethylene terephthalate hydrolase-cross-linked enzyme aggregate cross-linked with amylopectin (IsPETase/Amy) was developed and successfully degraded polyethylene terephthalate (PET). However, the low enzyme efficiency of IsPETase/Amy may hamper its industrial application. Hence, the goal of this study is to improve the enzyme efficiency of IsPETase-CLEAs by using novel dialdehyde amylopectin (DAA) from maize as cross-linker. DAA with aldehyde content of 64.3 % was synthesized and used to cross-link IsPETase as IsPETase/DAA. Under best immobilization condition, the activity recovery achieved was 74.3 %. Furthermore, IsPETase/DAA achieved 3.0-, 2.63-, 1.72- and 2.4-fold better thermal stability compared to IsPETase/Amy at 35 °C, 40 °C, 45 °C and 50 °C respectively. Moreover, better pH stability (pH 5-10) was achieved by IsPETase/DAA, and the reusability was enhanced to 7 cycles. Besides, enzyme efficiency of IsPETase/DAA successfully improved 7-fold better than IsPETase/Amy. It was revealed that IsPETase/DAA exhibited better PET degradation that the MHET yield was 66.2 % and 28 % higher than free IsPETase and IsPETase/Amy respectively. Therefore, this study developed a new promising green biocatalyst in PET degradation to be applied in industry.

Human serum albumin-coated cellulose beads for extracorporeal amyloid-beta scavenging: A promising Alzheimer's disease-modifying approach

Alzheimer's disease (AD) is a progressive neurodegenerative condition marked by cognitive decline, largely resulting from the accumulation of amyloid-beta (Aβ) plaques. Targeting Aβ has gained significant attention as a potential therapeutic approach for AD. In this study, cellulose beads (CBs) were covalently functionalized with human serum albumin (HSA). The functionalized CBs were extensively characterized using FTIR, SEM, XPS, and thermal analysis, confirming successful stepwise modification and HSA immobilization on their surface. The degree of HSA immobilization reached the highest level for fine CBs (50-75 μm), yielding 1.25 μg, 5.86 μg, and 6.45 μg of HSA per mg of beads treated with 1 %, 5 %, and 7 % HSA solutions, respectively. The GFP-Aβ fusion protein, recombinantly expressed and purified as a model ligand, was then adsorbed onto HSA-coated CBs and qualitatively analyzed by confocal microscopy. Quantitative adsorption studies demonstrated that HSA-coated CBs sequestered 335 ng/g of GFP-Aβ in PBS and 114 ng/g in human serum. Time-dependent and column-based assays also showed 318 ng/g sequestration capacities in PBS and 115 ng/g in human serum, respectively. These findings demonstrate HSA-functionalized CBs as a promising extracorporeal system for Aβ clearance, with vast potential therapeutic application as an AD modifying approach.

Selective synthesis of triacylglycerols by the ADS-17-supported Candida antarctica lipase B through esterification of oleic acid and glycerol

BACKGROUND

Immobilized enzyme possessing both high activity and good selectivity is important in practice. In this study, Candida antarctica lipase B (CALB) was immobilized onto the macroporous resin ADS-17 for triacylglycerol (TAG) synthesis through esterification of oleic acid and glycerol. The reaction conditions were optimized by single-factor study and orthogonal test, and the reusability of the immobilized CALB (CALB@ADS-17) was evaluated. In addition, the mechanism of lipase immobilization was studied and the catalytic mechanism of CALB@ADS-17 was investigated.

RESULTS

Oleic acid conversion up to 99.20% and TAG content at 91.58 wt% could be obtained under optimal conditions. In addition, the CALB@ADS-17 retained 84.28% of its initial activity after 11 cycles of reuse. The mechanism of lipase immobilization was through hydrophobic adsorption. The relationship between temperature and oleic acid conversion was lnV0 = 6.3316 - 4.3321/T, and the activation energy (Ea) was 36.02 kJ mol-1. CALB@ADS-17 did not exhibit an obvious interfacial activation phenomenon. Its kinetic behavior can be described by the Michaelis-Menten model, whose kinetic parameters of vmax, kcat, Km, Ki, and kcat/Km were 0.01265 μmol L-1 s-1, 9310.72 s-1, 0.4907 mmol L-1, 3.997 mmol L-1, and 1.90 × 104 L mmol-1 s-1, respectively.

CONCLUSION

CALB@ADS-17 showed good esterification performance and exhibited good selectivity towards TAG generation. In addition, CALB@ADS-17 exhibited good reusability in esterification reactions and has potential in practical applications. © 2025 Society of Chemical Industry.

Vinyl sulfone-amino-alkyl supports: heterofunctional matrixes to prevent enzyme release and stabilize lipases via covalent immobilization

New trifunctional supports were prepared (amino-octyl-vinyl sulfone (VS)- and amino-hexyl-VS-agarose) and compared to octyl-VS-agarose. They were utilized to immobilize the lipases A and B from Candida antarctica (CALA and CALB). After incubation to generate some enzyme-support bonds and blocking with different nucleophiles, SDS-PAGE analyses showed that all enzyme molecules become covalently immobilized on the support. In all VS biocatalysts, the blocking reagent presented a great effect in the properties of enzymes. The best blocking agents promoted a significant enzyme stabilization compared to the enzyme stability using the amino-alkyl-agarose supports, higher than that using octyl-VS-agarose supports, although these remained the most stable ones in most cases, as the octyl-biocatalysts were significantly more stable than the enzyme immobilized on amino-alkyl-support. Enzyme activities and specificities could be also greatly tuned by the immobilization in the new trifunctional supports, with enzyme activities in many instances enhancing that of the best non-covalently immobilized enzyme. That way, the results on this paper show that the properties of the enzymes when immobilized on these new trifunctional supports may be significantly tuned by the nature of the acyl chain in the support and the nature of the reagent used to block the reactivity of the remaining VS groups.

Polyethylenimine-Assisted Interfacial Modulation Based on Electrostatic Balancing and Hierarchical Channel to the Cytidine 5'-Monophosphate Conversion Performance of Uridine-Cytosine Kinase

Interfacial modulation of protein microenvironments plays a pivotal role in enhancing enzyme immobilization and catalysis. In this study, we proposed a polyethylenimine (PEI)-assisted strategy that combines electrostatic and affinity interactions to improve the performance of Cytidine 5'-Monophosphate (CMP) conversion by uridine-cytidine kinase (UCK). The PEI-modified interface creates an optimal local microenvironment that maintains a balanced charge distribution, stabilizes UCK's conformation, and prevents denaturation. Electrostatic interactions promote product adsorption, enhance diffusion, and reduce substrate accumulation, boosting reaction efficiency. The kinetic assays revealed an increase in the maximum reaction rate from 16.8 to 113.2 μM·min-1 with a remarkable increase in substrate affinity and enzyme activity. The relative enzyme activity at the optimal substrate concentration increased from 70.4 to 106.9%, and by 113.3% under conditions of substrate inhibition. This study provides theoretical and technical support for the efficient production of CMP with promising applications in food, feed, and medical fields.

Urease-coupled systems and materials: design strategies, scope and applications

Synthetic systems have co-opted urease, a crucial enzyme serving many biological functions, to recapitulate complex biological features. Therefore, the urease-urea feedback reaction network (FCRN) is reciprocated with soft materials to induce various animate-like features, including self-regulation, error correction, and decision-making capabilities, that are processed through a variety of non-linear functions. Although free-urease-based homogeneous systems are capable of adhering to many non-linear characteristics, they lack the ability to showcase the diffusion-controlled spatiotemporal phenomena. Therefore, it demands urease immobilization, whereby a compartmentalized reaction hub can facilitate the interplay of FCRN with reaction diffusion to regulate the system's operation, allowing various non-linear responses and spatiotemporal self-organization. Indeed, the beneficial framework of urease-based commercial systems in modern technology necessitates the accessibility, reusability, and long-term stability of urease. Consequently, several techniques for urease immobilization merit attention. This review highlights the diverse covalent and non-covalent approaches for urease immobilization on different substrates and illustrates several chemical reactions and non-covalent interactions as tools for creating targeted systems and soft materials to realize many on-demand functions. We also emphasize how the advancement of systems chemistry has propelled research in soft materials to comprehend system-level applications by demonstrating several emerging non-linear functions with potent applications in many directions, including sensing, soft robotics, regulation of material properties and many more.

Decorating channel walls in ordered macroporous ZIF-8 with hydrophilic PEG to immobilize lipase for efficient chiral resolution

The development of efficient immobilization support for the enhancement of enzyme activity and recyclability is a highly desirable objective. Single-crystalline ordered macro-microporous ZIF-8 (SOM-ZIF-8), has emerged as a highly effective matrix for enzyme immobilization, however, the inherent hydrophobic nature limits its further advancement. Herein, we have customized the immobilization of the Pseudomonas cepacia lipase (LP) in the modification-channels of SOM-ZIF-8 by functionalizing the inner surface-properties with polyethylene glycol (PEG) (LP@SOM-ZIF-8-PEG), and significant enhancement of the activity and (thermal, solvent and cyclic) stability can be realized. The incorporation of PEG into SOM-ZIF-8 regulates its inner surface charge and hydrophobic properties, thereby enhancing enzyme loading, facilitating enzyme conformational adjustments, and achieving a uniform dispersion of LP in SOM-ZIF-8-PEG. LP@SOM-ZIF-8-PEG not only demonstrates a pronounced elevation in enzyme loading and activity over LP@SOM-ZIF-8 but also shows an enzyme activity that is impressively three times greater than LP@ZIF-8. It can completely resolve the 1-phenylethanol racemate in 60 min, with a conversion close to 50 % and an enantioselectivity of 99.8 %. After nine cycles of reuse, the LP@SOM-ZIF-8-PEG still holds onto 95 % of its initial activity. The excellent catalytic performance and stability of LP@SOM-ZIF-8-PEG, along with the universality of the PEG modification strategy for other enzymes, make this work promising in industrial applications.

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.

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.

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.

Nano-structured polyaniline in biocatalysis: Manifesting simultaneous competence of polyaniline nanofibers and nanotubes as immobilization matrices for laccase mediated synthesis of drug intermediates

Customized nano-biocatalysts of laccase have been made using nano-structured polyaniline viz. nano-fibers and nano-tubes, as immobilization supports and a simultaneous comparison between them has been made. Laccases are poly-phenol oxidases having tremendous utility concerning wider areas of application especially in the field of organic and drug syntheses. Considering importance of laccases in drug syntheses, an effort has been made to immobilize laccase on the nano-structured polyaniline by adsorption. Immobilization was assessed using percentage enzyme loading as well as immobilization efficiency. Further immobilization process was strengthened using statistical optimization (Response Surface Methodology) for the parameters affecting immobilization viz. pH, Stirring rate, Enzyme Support ratio. In comparison to free enzyme, better thermal stability was depicted with almost 3- and 4-fold increase in half-life for immobilized laccase on nanofibers and nanotubes, respectively, at 80 °C. The storage stability of the nano-biocatalysts was revealed by the retention >50 % of higher enzyme activity in comparison to free form, when stored at 4 °C for up to 60 days. Moreover, slow and gradual decline in activity was observed when the immobilized laccase preparations were re-utilized for ten consecutive cycles of guaiacol oxidation. Greater than 60 % retention of enzyme activity after consistent catalytic cycles renders the utilization of immobilization preparations in industrial biocatalysis. Manifestation of efficient nano-biocatalysts has portrayed superior enzyme kinetics in rendering efficient biotransformations of ortho-phenylenediamine analogues to subsequent Phenazines which are known to possess therapeutic properties ranging from anti-microbial to anti-proliferative and so on.

Emergence of ADM-mediated bioconjugate to enhance longevity and catalytic efficiency of urease

The versatile nature of the urease enzyme makes it a valuable asset in biological and industrial contexts. The creation of bioconjugates using enzyme-polymer combinations has extended the shelf life and stability of urease. A triblock copolymer, PAM-co-PDPA-co-PMAA@urease (ADM@urease), was synthesized using acrylamide (AM), 2,5-dioxopyrrolidin-1-ylacrylate (DPA), methacrylic acid (MAA), and urease via the RAFT-Grafting-To polymerization method. This polymeric interface stabilizes the enzyme and enhances substrate binding and product release, significantly boosting enzymatic efficiency. To enhance pH's influence on urease activity, three ADM grades were developed by adjusting pH-responsive MAA levels, confirmed by GPC analysis. ADM micellized at acidic pH values of 6.47 or lower, with a critical micelle concentration (CMC) of at least 0.125 mg/mL. Kinetic evaluations using Berthelot reagents at various pH levels and temperatures compared free enzyme and urease encapsulated in ADM@urease. The Michaelis-Menten constant (Km) values, derived from the Lineweaver-Burk plot, were similar for both forms. The ADM@urease demonstrated optimal stability and catalytic efficacy with a Km value of 1.18 and Vmax of 1.92 at pH 4. By improving the stability, efficiency, and performance of urease, this encapsulation technology offers potential for sustainable, eco-friendly industrial applications and advancements in biotechnology.

Functional Monomers Equipped Microgel System for Managing Parkinson's Disease by Intervening Chemokine Axis-mediated Nerve Cell Communications

The complex pathology of Parkinson's disease (PD) requires comprehensive understanding and multi-pronged interventions for communication between nerve cells. Despite new developments in nanotechnology in the treatment of PD, in-depth exploration of their biological effects, in particular, the specific mechanisms of inflammation inhibition are lacking. Herein, using the stable cascade catalysis channel formed by polydopamine (PDA), imidazole groups, and Cu ions, a microgel system comprising functional monomers [superoxide dismutase (SOD) with double bonds, PDA, 2-methacryloyloxy ethyl phosphorylcholine (MPC), and Cu ions] is proposed for managing PD. The microgel can be efficiently delivered to the brain aided by MPC, after which a multi-level regulatory strategy targeting neurons and microglia can be initiated. The catalytic activity cascade elicited by SOD and Cu ions can regulate the anti-inflammatory phenotypic transformation of microglia by relieving oxidative stress. Meanwhile, the dopamine (DA) released from PDA can facilitate DA storage and neurogenesis, inhibiting CX3CL1 release and the CX3CR1 receptor on microglia and further regulating the CX3CL1/CX3CR1-NF-κB-NLRP3 signaling pathway in microglia to inhibit neuroinflammation. Therefore, the proposed microgel delivery system with functional monomers represents a promising therapeutic strategy for managing neuroinflammation and promoting neurogenesis in PD by intervening chemokine axis-mediated communication between neurons and microglia.

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.

Unveiling the role of mechanical process intensifications and chemical additives in boosting lipase-catalyzed hydrolysis of vegetable oil for fatty acid production: A comprehensive review

The enzymatic production of fatty acids from vegetable oils is becoming a preferred method due to its mild conditions, simplicity, and scalability. This review analyzes studies on enzymatic hydrolysis, exploring various feedstocks, lipases, reaction conditions, and conversion yields. However, a key limitation is the longer reaction time compared to conventional methods. This limitation is primarily due to the immiscibility of triacylglycerols (TAGs) with water at low temperatures and pressures, as well as the lower activity of enzymes compared to chemical catalysts. To overcome these issues, chemical additives are identified as the most effective process intensification strategy. They are easy to implement, cause less damage to lipases, and are more efficient than mechanical methods. The impact of various chemical additives was thoroughly examined for potential improvements in the enzymatic hydrolysis of vegetable oils. A synergistic combination of chemical additives comprising ionic liquids (ILs) and polyols, along with ultrasound, as well as the consideration of immobilization techniques were explored. Overall, this review highlights the potential of chemical additives and their synergistic feasibility in enhancing the enzymatic performance of lipase-catalyzed hydrolysis reactions.

Improved catalytic stability of immobilized Candida antarctica lipase B on macroporous resin with organic polymer coating for biodiesel production

Lipase is one of the most widely studied and applied biocatalysts. Due to the high enzyme leakage rate of the immobilization method of physical adsorption, we propose a new lipase immobilization method, based on the combination of macroporous resin adsorption and organic polymer coating. The immobilized Candida antarctica lipase B (CALB@resin-CAB) was prepared by combining the macroporous resin adsorption with cellulose acetate butyrate coating, and its structure was characterized by various analytic methods. Immobilized lipase was applied for biodiesel production using acidified palm oil as the starting material, the conversion rate achieved as high as 98.5% in two steps. Furthermore, the immobilized lipase displayed satisfactory stability and reusability in biodiesel production. When the aforementioned reaction was carried out in a continuous flow packed bed system, the yield of biodiesel was 94.8% and space-time yield was 2.88 g/(mL∙h). The immobilized lipase CALB@resin-CAB showed high catalytic activity and stability, which has good potential for industrial application in the field of oil processing.

Evaluation of cross-linkers in the design of immobilized multi isomerase cascade for the preparation of rare sugars

The cascade of sugar isomerases is one of the most practical methods for producing rare sugars, and enzyme immobilization endows it with high economic efficiency, operational convenience and reusability. However, the most employed cross-linker glutaraldehyde (GA) has the disadvantages of enzyme deactivation and limitation of substrate binding. Herein, three compounds, glyoxal, GA, and 2,5-furandicarboxaldehyde (DFF) were evaluated within a previously developed cascade comprising ribose-5-phosphate isomerase and D-tagatose-3-epimerase to prepare D-ribulose form D-xylose. Analyses of surface morphology, element and chemical bond revealed that all compounds effectively cross-linked the isomerases. High concentration of the cross-linkers was generally beneficial for binding protein and preventing enzyme leak during reusing cycles. Glyoxal performed the highest immobilization rate, though it hadn't been employed as a cross-linker for enzyme immobilization. DFF mediated cross-linking revealed the highest activity recovery, substrate conversion and residual activity after reusing cycles, suggesting better biocompatibility than glyoxal and GA. After 8 rounds of recycling, the residual activity of enzyme immobilized by DFF was 61.4 %, ∼30 % higher than that of GA. This study proved a potential alternative cross-linker DFF for the immobilization of enzyme cascade with high activity recovery and reusability, which could promote the efficient production of high value-added products from biomass monosaccharides.

Computational and biochemical characterization of the immobilized esterase of Salinicoccus roseus for pesticide degradation

The continuous exposure of chemical pesticides in agriculture, their contamination in soil and water pose serious threat to the environment. Current study used an approach to evaluate various pesticides like Hexaconazole, Mancozeb, Pretilachlor, Organophosphate and λ-cyhalothrin degradation capability of esterase. The enzyme was isolated from Salinicoccus roseus. Genome analysis unveiled the carboxylesterase genes underlying the degradation of pesticides, and was located between 2070Mbp to 2080Mbp region. Herein, partially purified esterase was immobilized into beads by mixing with an equal volume (1:1) of sodium alginate solution [2.5% (w/v)].Scanning electron microscopy (SEM) of the beads showed the microspheres for enhanced enzyme-substrate reaction, wide peak at 3316, 1635 and 696 cm- 1 in Fourier-transform infrared spectroscopy (FTIR) represented intermolecular hydrogen bonding, and thermogravimetric analysis (TGA) reaffirmed the binding of esterase entrapped into the beads. Maximum degradation rate (after 4 days) for free enzyme accounted 83.2% in Hexaconazole. Degradation rate moderately increased 4% in the presence of immobilized esterase. Degradation products were detected by liquid chromatography-mass spectrometry (LC-MS). Cytotoxicity test (root length and mitotic index) revealed differences in various treatments. Enzyme kinetics parameters, Michaëlis-Menten constant (KM) 6.61 mM and maximum velocity (Vmax) 1.89 µmol/min/mg increased after immobilization. Further, molecular docking results validated that esterase contributed to pesticide degradation by catalytic triad of Ser93-His222-Phe24, ligand interactions, and specific binding pockets. Additionally, molecular dynamics (MD) simulations confirmed the protein-ligand conformational stability. Hence, present study highlighted an effective method for improving the catalytic properties of esterase, and also potential candidate for bioremediation of pesticides.

Modulating membrane-bound enzyme activity with chemical stimuli

Membrane-bound enzymes play pivotal roles in various cellular processes, making their activity regulation essential for cellular homeostasis and signaling transduction. Given that dysregulation of membrane-bound enzymes involved in various disease, controlling enzyme activity offers valuable avenues for designing targeted therapies and novel pharmaceutical interventions. This review explores chemical stimuli-responsive strategies for modulating the activity of these enzymes, employing diverse stimuli such as small molecules, proteins, nucleic acids, and bifunctional molecules to either inhibit or enhance their catalytic function. We systematically delineate the mechanisms underlying enzyme activity regulation, including substrate binding site blockade, conformational changes, and local concentration of enzymes and substrates. Furthermore, based on some examples, we elucidate the binding modalities between stimuli and enzymes, along with potential modes of regulation, and discuss their potential medical applications and future prospects. This review underscores the significance of understanding and manipulating enzyme activity on the cell membrane for advancing biomedical research and therapeutic development.

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.

Long chain capsaicin analogues synthetized by CALB-CLEAs show cytotoxicity on glioblastoma cell lines

Glioblastoma is one of the most lethal tumors, displaying striking cellular heterogeneity and drug resistance. The prognosis of patients suffering from glioblastoma after 5 years is only 5%. In the present work, capsaicin analogues bearing modifications on the acyl chain with long-chain fatty acids showed promising anti-tumoral activity by its cytotoxicity on U-87 and U-138 glioblastoma multiforme cells. The capsaicin analogues were enzymatically synthetized with cross-linked enzyme aggregates of lipase B from Candida antarctica (CALB). The catalytic performance of recombinant CALB-CLEAs was compared to their immobilized form on a hydrophobic support. After 72 h of reaction, the synthesis of capsaicin analogues from linoleic acid, docosahexaenoic acid, and punicic acid achieved a maximum conversion of 69.7, 8.3 and 30.3% with CALB-CLEAs, respectively. Similar values were obtained with commercial CALB, with conversion yields of 58.3, 24.2 and 22% for capsaicin analogues from linoleic acid, DHA and punicic acid, respectively. Olvanil and dohevanil had a significant cytotoxic effect on both U-87 and U-138 glioblastoma cells. Irrespective of the immobilization form, CALB is an efficient biocatalyst for the synthesis of anti-tumoral capsaicin derivatives. KEY POINTS: • This is the first report concerning the enzymatic synthesis of capsaicin analogues from docosahexaenoic acid and punicic acid with CALB-CLEAs. • The viability U-87 and U-138 glioblastoma cells was significantly affected after incubation with olvanil and dohevanil. • Capsaicin analogues from fatty acids obtained by CALB-CLEAs are promising candidates for therapeutic use as cytotoxic agents in glioblastoma cancer cells.

Glucose Oxidase-Immobilized Dually-Crosslinked Nanogels for Rapid-Responsive Insulin Delivery

Despite the potential benefits of close-looped insulin delivery systems in regulating glycemic homeostasis and effectively alleviating diabetes, they still encounter challenges such as limited effectiveness in preventing low glycemic episodes due to sluggish glucose response, and issues with the instability of enzymes and carriers. In this study, dually-crosslinked and glucose oxidase (GOx)-immobilized insulin nanogels (DC-NGs@Ins) are developed for rapid-responsive and sustained hypoglycemic therapy. The DC-NGs@Ins with the phenylborate ester linker enabled the insulin release in a close-looped fashion, and moreover, immobilized GOx-generated hydrogen peroxide (H2O2) by consuming the glucose, which can further bind to phenylborate ester for enhancing glucose response and accelerating the insulin release. The dually-crosslinked structure (phenylboronic ester and UV-crosslinking) effectively minimized the initial burst release of insulin, thus preventing the potential risk of hypoglycemia. More interestingly, GOx immobilized in the nanogels mitigated GOx leakage and enhanced its multiple utilization compared to free GOx. In vivo study demonstrated that DC-NGs@Ins effectively maintained glycemic levels (BGLs) below 200 mg dL-1 for at least 8 h compared to singly-crosslinked nanogels (SC-NGs@Ins). Therefore, this intelligent insulin delivery system shows potential applications in diabetes treatment.

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.

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.

Papain functionalized Prussian blue nanozyme colloids of triple enzymatic function

Prussian blue nanozymes were surface engineered with papain enzyme to develop processable nanoparticle dispersions with antioxidant and hydrolytic activities for biocatalytic applications. Enzyme coating improved the colloidal stability of the nanozymes and the obtained papain-Prussian blue hybrid showed remarkable peroxidase (vmax = 8.82 × 10-9 M s-1, KM = 12.3 mM), superoxide dismutase (IC50 = 14.6 ppm) and protease-like (41.2 U L-1) activities.

Incorporation of enzyme-mimic species in porous materials for the construction of porous biomimetic catalysts

The unique catalytic properties of natural enzymes have inspired chemists to develop biomimetic catalyst platforms for the intention of retaining the unique functions and solving the application limitations of enzymes, such as high costs, instability and unrecyclable ability. Porous materials possess unique advantages for the construction of biomimetic catalysts, such as high surface areas, thermal stability, permanent porosity and tunability. These characteristics make them ideal porous matrices for the construction of biomimetic catalysts by immobilizing enzyme-mimic active sites inside porous materials. The developed porous biomimetic catalysts demonstrate high activity, selectivity and stability. In this feature article, we categorize and discuss the recently developed strategies for introducing enzyme-mimic active species inside porous materials, which are based on the type of employed porous materials, including metal-organic frameworks (MOFs), covalent organic frameworks (COFs), molecular sieves, porous metal silicate (PMS) materials and porous carbon materials. The advantages and limitations of these porous materials-based biomimetic catalysts are discussed, and the challenges and future directions in this field are also highlighted.

Integrating Biocatalysts into Metal-Organic Frameworks: Disentangling the Roles of Affinity, Molecular Weight, and Size

The integration of biocatalysts within metal-organic frameworks (MOFs) is attracting growing interest due to its potential to both enhance biocatalyst stability and sustain biocatalyst activity in organic solvents. However, the factors that facilitate the post-synthetic infiltration of such large molecules into MOF pores remain unclear. This systematic study enabled the identification of the influence of biocatalyst molecular size, molecular weight and affinity on the uptake by an archetypal MOF, NU-1000. We analyzed a range of six biocatalysts with molecular weights from 1.9 kDa to 44.4 kDa, respectively. By employing a combination of fluorescence tagging and 3D-STED confocal laser scanning microscopy, we distinguished between biocatalysts that were internalized within the MOF pores and those sterically excluded. The catalytic functions of the biocatalysts hosted within the MOF were investigated and found to show strong variations relative to the solvated case, ranging from a two-fold increase to a strong decrease.

Designing mixed cationic/anionic supports to covalently immobilize/stabilize enzymes with high isoelectric point by enzyme adsorption and support-enzyme glutaraldehyde crosslinking

Ficin fully immobilized on Asp-agarose beads at pH 7 but not on an aminated support. This made enzyme adsorption plus glutaraldehyde modification non-viable for this enzyme. Modifying glyoxyl-agarose beads with mixtures of Asp and 1,6-hexamethylenediamine (HA) at different ratios, mixed anion/cation exchanger supports were built. Only if HA greatly exceed Asp in the support, immobilization did not work. While only using the Asp-agarose support immobilized enzyme molecules were only ionically adsorbed after glutaraldehyde treatment (visualized in SDS-PAGE analysis), the mixed supports gave covalent immobilization. The glutaraldehyde modification of these biocatalysts permitted to establish covalent bonds with the support, and this was more effective when using higher amounts of HA in the support. When around 60 % of the groups in the support were HA, the treatment with glutaraldehyde fully suppressed enzyme release from the support after boiling in SDS. The glutaraldehyde treated biocatalysts were more stable than just the adsorbed enzymes or the enzyme adsorbed only on Asp supports and then treated with glutaraldehyde (the optimal biocatalyst retained 90 % of the initial activity while the just adsorbed ficin retained 50 % of the initial activity). This strategy can be utilized to immobilize other proteins with high isoelectric points following this immobilization strategy.

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.

Optical scattering methods for the label-free analysis of single biomolecules

Single-molecule techniques to analyze proteins and other biomolecules involving labels and tethers have allowed for new understanding of the underlying biophysics; however, the impact of perturbation from the labels and tethers has recently been shown to be significant in several cases. New approaches are emerging to measure single proteins through light scattering without the need for labels and ideally without tethers. Here, the approaches of interference scattering, plasmonic scattering, microcavity sensing, nanoaperture optical tweezing, and variants are described and compared. The application of these approaches to sizing, oligomerization, interactions, conformational dynamics, diffusion, and vibrational mode analysis is described. With early commercial successes, these approaches are poised to have an impact in the field of single-molecule biophysics.

Chitosan-Based Charge-Controllable Supramolecular Carrier for Universal Immobilization of Enzymes with Different Isoelectric Points

Electrostatic adsorption is an enzyme immobilization method that effectively maintains enzyme activity and exhibits considerable binding efficiency. However, enzymes carry different charges at their respective reaction pH levels, which prevents the use of the same carrier to immobilize enzymes with different charges. In this study, we employed a template-mediated polysaccharide-enzyme coupling self-assembly strategy to develop a charge-controllable supramolecular immobilization carrier by regulating the charge properties of carboxymethyl chitosan, enabling the universal immobilization of enzymes with different charge levels across a range of reaction pH values. By using silica nanoparticles of certain sizes as templates, the size of the carrier can be precisely controlled and the hollow network structure formed after removing the template can effectively reduce mass transfer resistance. Trypsin and papain are used as model enzymes, and the experimental results show that the supramolecular self-assembly immobilization strategy does not disrupt the secondary structure of the enzyme molecules. After 2 h of reaction, the enzyme activities of immobilized papain and immobilized trypsin are 13.2% and 7.7% higher than those of the free enzymes, respectively. After 10 consecutive reactions, the enzyme activities of immobilized papain and immobilized trypsin retained 56.3% and 64.3% of their initial values, respectively.

Exploring enzyme-immobilized MOFs and their application potential: biosensing, biocatalysis, targeted drug delivery and cancer therapy

Enzymes are indispensable in several applications including biosensing and degradation of pollutants and in the drug industry. However, adverse conditions restrict enzymes' utility in biocatalysis due to their inherent limitations. Metal-organic frameworks (MOFs), with their robust structure, offer an innovative avenue for enzyme immobilization, enhancing their resilience against harsh solvents and temperatures. This advancement is pivotal for application in bio-sensing, bio-catalysis, and specifically, targeted drug delivery in cancer therapy, where enzyme-MOF composites enable precise therapeutic localization, minimizing the side effects of traditional treatment. The adaptable nature of MOFs enhances drug biocompatibility and availability, significantly improving therapeutic outcomes. Moreover, the integration of enzyme-immobilized MOFs into bio-sensing represents a leap forward in the rapid and accurate identification of biomarkers, facilitating early diagnosis and disease monitoring. In bio-catalysis, this synergy promotes efficient and environmentally safe chemical synthesis, enhancing reaction rates and yields and broadening the scope of enzyme application in pharmaceutical and bio-fuel production. This review article explores the immobilization techniques and their biomedical applications, specifically focusing on drug delivery in cancer therapy and bio-sensing. Additionally, it addresses the challenges faced in this expanding field.

Enzymes encapsulated in organic-inorganic hybrid nanoflower with spatial localization for sensitive and colorimetric detection of formate

Formate is an important environmental pollutant, and meanwhile its concentration change is associated with a variety of diseases. Thus, rapid and sensitive detection of formate is critical for the biochemical analysis of complex samples and clinical diagnosis of multiple diseases. Herein, a colorimetric biosensor was constructed based on the cascade catalysis of formate oxidase (FOx) and horseradish peroxidase (HRP). These two enzymes were co-immobilized in Cu3(PO4)2-based hybrid nanoflower with spatial localization, in which FOx and HRP were located in the shell and core of nanoflower, respectively (FOx@HRP). In this system, FOx could catalyze the oxidation of formate to generate H2O2, which was then utilized by HRP to oxidize 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid to yield blue product. Ideal linear correlation could be obtained between the absorbance at 420 nm and formate concentration. Meanwhile, FOx@HRP exhibited excellent detection performance with low limit of detection (6 μM), wide linear detection range (10-900 μM), and favorable specificity, stability and reusability. Moreover, it could be applied in the detection of formate in environmental, food and biological samples with high accuracy. Collectively, FOx@HRP provides a useful strategy for the simple and sensitive detection of formate and is potentially to be used in biochemical analysis and clinical diagnosis.

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.

Water-mediated active conformational transitions of lipase on organic solvent interfaces

When it comes to enzyme stability and their application in organic solvents, enzyme biocatalysis has emerged as a popular substitute for conventional chemical processes. However, the demand for enzymes exhibiting improved stability remains a persistent challenge. Organic solvents can significantly impacts enzyme properties, thereby limiting their practical application. This study focuses on Lipase Thermomyces lanuginose, through molecular dynamics simulations and experiments, we quantified the effect of different solvent-lipase interfaces on the interfacial activation of lipase. Revealed molecular views of the complex solvation processes through the minimum distance distribution function. Solvent-protein interactions were used to interpret the factors influencing changes in lipase conformation and enzyme activity. We found that water content is crucial for enzyme stability, and the optimum water content for lipase activity was 35 % in the presence of benzene-water interface, which is closely related to the increase of its interfacial activation angle from 78° to 102°. Methanol induces interfacial activation in addition to significant competitive inhibition and denaturation at low water content. Our findings shed light on the importance of understanding solvent effects on enzyme function and provide practical insights for enzyme engineering and optimization in various solvent-lipase interfaces.

Robust peroxidase from Bacillus mojavensis TH309: Immobilization on walnut shell hydrochar and evaluation of its potential in dye decolorization

Peroxidases have received considerable attention as a cost-effective and environmentally friendly catalyst for bioremediation. Their rapid activity loss under harsh environmental conditions and inability to be used repetitively limit their exploitation in real-world wastewater treatment. First, a peroxidase was produced extracellularly by Bacillus mojavensis TH309 and purified 8.12-fold with a final yield of 47.10 % using Sephadex G-100 superfine resin. The pure peroxidase (BmPer) possessed a relatively low molecular weight of ∼21 kDa and was active against L-DOPA on acrylamide gel after electrophoresis. BmPer was immobilized by adsorption functionalized walnut shell hydrochar (WsH) with 61.99 ± 1.34 % efficiency and 37.07 ± 4.16 % activity loss. BmPer and its immobilized form (WsH-BmPer) exhibited maximum activity at 50 °C and pH 9. WsH-BmPer exhibited 3.23-, 2.37-, 1.65-, and 2.25-fold longer half-life than BmPer at 50, 60, 70, and 80 °C, respectively. Immobilization significantly enhanced the stability of the enzyme under acidic conditions. BmPer and WsH-BmPer showed maximal activity in the presence of 1 % salt and retained more than 85 % of their activity even after pre-incubation with 2.5 M salt for 60 min at 50 °C. Their catalytic efficiency was significantly stimulated by pre-incubation with Triton X-100 (1 mM), Tween20 (1 mM), and Mg2+ (1 and 10 mM). Immobilization strongly reduced the loss of activity caused by inhibitors including Ba2+, Hg2+, and Cu2+. Moreover, both forms of the enzyme were compatible with solvents. The Michaelis constant (Km) values of BmPer and WsH-BmPer were 0.88 and 2.66 mM for 2,4 DCP, respectively. WsH-BmPer peroxidase maintained about 82 % and 85 % of its activity when stored at 4 °C for 30 days and reused for up to 10 cycles, respectively. Furthermore, it decolorized Cibacron red (CR), Poly R-478 (PR), Remazol Brilliant Blue R (RBBR), and Methyl red (MR) dyes by 60.13 %, 91.34 %, 86.41 %, and 50.51 % within 60 min, respectively.

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.

Substrate specificity of commercial lipases activated by a hydration-aggregation pretreatment in anhydrous esterification reactions

Substrate specificity in non-aqueous esterification catalyzed by commercial lipases activated by hydration-aggregation pretreatment was investigated. Four microbial lipases from Rhizopus japonicus, Burkholderia cepacia, Rhizomucor miehei, and Candida antarctica (fraction B) were used to study the effect of the carbon chain length of saturated fatty acid substrates on the esterification activity with methanol in n-hexane. Hydration-aggregation pretreatment had an activation effect on all lipases used, and different chain length dependencies of esterification activity for lipases from different origins were demonstrated. The effects of various acidic substrates with different degrees of unsaturation, aromatic rings, and alcohol substrates with different carbon chain lengths on esterification activity were examined using R. japonicus lipase, which demonstrated the most remarkable activity enhancement after hydration-aggregation pretreatment. Furthermore, in the esterification of myristic acid with methanol catalyzed by the hydrated-aggregated R. japonicus lipase, maximum reaction rate (5.43 × 10-5 mmol/(mg-biocat min)) and Michaelis constants for each substrate (48.5 mM for myristic acid, 24.7 mM for methanol) were determined by kinetic analysis based on the two-substrate Michaelis-Menten model.

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.

Non-carrier immobilization of yeast cells by genipin crosslinking for the synthesis of prebiotic galactooligosaccharides from plant-derived galactose

Galactooligosaccharides (GOS), as mimics of human milk oligosaccharides, are important prebiotics for modulating the ecological balance of intestinal microbiota. A novel carrier-free cell immobilization method was established using genipin to cross-link Kluyveromyces lactis CGMCC 2.1494, which produced β-galactosidase, an enzyme essential for GOS synthesis. The resulting immobilized cells were characterized as stable by thermogravimetric analysis and confirmed to be crosslinked through scanning electron microscopy analysis (SEM) and Fourier transform infrared spectroscopy (FTIR). The Km and Vmax values of β-galactosidase in immobilized cells towards o-nitrophenyl β-D-galactoside were determined to be 3.446 mM and 2210 μmol min-1 g-1, respectively. The enzyme in the immobilized showed higher thermal and organic solvent tolerance compared to that in free cells. The immobilized cells were subsequently employed for GOS synthesis using plant-derived galactose as the substrate. The synthetic reaction conditions were optimized through both single-factor experiments and response surface methodology, resulting in a high yield of 49.1 %. Moreover, the immobilized cells showed good reusability and could be reused for at least 20 batches of GOS synthesis, with the enzyme activity remaining above 70 % at 35 °C.

Activation of Inert Supports for Enzyme(s) Immobilization Harnessing Biocatalytic Sustainability for Perennial Utilization

Although Nature's evolution and intelligence have gifted humankind with noteworthy enzyme candidates to simplify complex reactions with ultrafast, overselective, effortless, mild biological reactions for millions of years, their availability at minute-scale, short-range time-temperature stability, and purification costs hardly justify recycling/or reuse. Covalent immobilization, particularly via multipoint bonds, prevents denaturing, maintains activities for long-range time, pH, and temperature, and makes catalysts available for repetitive usages; which attracts researchers and industries to bring more immobilized enzyme contenders in science and commercial progressions. Inert-support activation, the most crucial step, needs appropriate activators; under mild conditions, the activator's functional group(s) still present on the activated support rapidly couples the enzyme, preventing unfolding and keeping the active site alive. This review summarizes exciting experimental advances, from the 1950s until today, in the activation strategies of various inert supports with five different surface activators, the cyanogen bromide, the isocyanate/isothiocyanate, the glutaraldehyde, the carbodiimide (with or without N-hydroxysuccinimide (NHS)), and the diazo group, for the immobilization of diverse enzymes for broader applications. These activators under mild pH (7.5 ± 0.5) and temperature (27 ± 3 °C) and ordinary stirring witnessed support activation and enzyme coupling and put off unfolding, harnessing addressable activities (CNBr: 40 ± 10%; -N═C═O/-N═C═S: 32 ± 7%; GA: 70 ± 15%; CDI: 60 ± 10%; -N+≡N: 80 ± 15%), while underprivileged stability, longevity, and reusabilities keep future investigations alive.

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.

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.