Enzyme stability and stabilization—Aqueous and non-aqueous environment

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.

Macromolecular crowding effect on the β-galactosidase cascade reaction under multivalency and chain overlapping conditions of glycopolymers

Enzymes catalyze cascade reactions in a crowded cellular environment where as much as half of cell volume is occupied by various macromolecules. Nonspecific interaction between enzymes and crowders and excluded volume of the crowders can superimpose on each other and complicate catalytic activity of the enzymes. This study investigates the interaction between a β-galactosidase (β-Gal) and glycosylated acrylamide polymer (P(Glc-β-EAAm)) and unravels the macromolecular crowding effect of the glycopolymer on enzymatic cascade catalysis consisting of β-Gal, glucose oxidase and hydrogen peroxidase. Binding of the glycopolymer induced conformational alterations in β-Gal and gave rise to static fluorescence quenching and stable complex formation with β-Gal via nonspecific interaction. Fluorescence resonance energy transfer assays further demonstrated a compact association between β-Gal and glycopolymer crowders, with binding affinity correlating with the molecular weight of glycopolymer. The reduction of the apparent kinetic constants of the catalysis with the glycopolymer size showed the role of the multivalent effect in enzyme-substrate interactions. The kinetics also depended on the chain overlapping conditions of the crowders. Therefore, the macromolecular crowding effect on the cascade reaction is jointly associated with the crowder's multivalent effect, chain overlapping conditions of the crowders, in addition to the volume exclusion effect of the crowders.

Enzyme Surface Residues Direct Encapsulation into Metal-Organic Frameworks for Performance Regulation

Herein, we highlight the role of nitrogen-enriched surface groups on proteins in directing topological transformations of metal-organic frameworks (MOFs). Using a modified-protein-directed MOFs template synthesis (mDTS) strategy, we demonstrate that these surface modifications on cytochrome c (Cyt c) selectively induce the formation of leaf-like zeolitic imidazolate frameworks (ZIF-L). This approach not only enables a structural transition from ZIF-8 to a more open ZIF-L framework but also substantially enhances the catalytic activity and loading of Cyt c beyond traditional immobilization methods. Adjusting the concentration of the surface modifier allows for precise tuning of the Cyt c activity, allowing optimal enzyme function at specific modifier levels. Furthermore, our results reveal that surface modifications of a variety of proteins can facilitate the formation of ZIF-L, emphasizing the broad applicability of the mDTS method. This approach offers significant promise for developing highly efficient protein-MOF composites, offering transformative potential for industrial catalysis and biotechnological applications.

Rational design strategy for thermostability enhancement of protein-glutaminase and investigation of the underlying mechanisms

Protein-Glutaminase (PG) with efficient deamidation ability has shown vital potential in food fields. Enzymes with high thermostability remain active in high-temperature environments, which can be applied to some steps requiring high temperature treatment in food processing, thereby greatly expanding their industrial application. In this study, an efficient comprehensive strategy based on consensus sequence and computer-aid analysis was proposed to develop a combinatorial mutant mPG-5M (A79S/T97V/S108P/N154D/L156Y), exhibiting a 55.1-fold increase in t1/2 at 60 °C (1132.75 min) and a Tm value of 75.21 °C without loss of enzyme activity. Molecular dynamics simulation analysis insisted that the reduced flexibility, increased structural rigidity, and enhanced hydrogen bonding network observed in the mPG-5M all contribute to its superior stability, particularly under thermal stress. This study provided valuable strategy and comprehensive molecular mechanisms insights for protein engineering of the thermostability enhancement of PG, broadening its industrial applicability of food protein deamidation. These mutations collectively contributed to the enhanced thermal stability of the mPG-5M mutant.

Sustainable synthesis of alginate-cobalt ferrite nanocomposites for horseradish peroxidase immobilization: enhanced stability, reusability, and catalytic efficiency

This study explores the green synthesis of an alginate-cobalt ferrite (Alg-CoFe2O4) composite using Brachychiton populneus extract for horseradish peroxidase (HRP) immobilization, targeting enhanced enzyme stability and reusability. The Alg-CoFe2O4 composite, synthesized via co-precipitation and calcination at 600 °C, was characterized using XRD, VSM, SEM-EDX, BET, FT-IR, and zeta potential analysis, confirming its structural, magnetic, and surface properties. HRP immobilization via glutaraldehyde crosslinking achieved a high immobilization yield of 84%, attributed to the composite's high surface area and covalent binding efficiency. Kinetic analysis revealed an increased Km (30 mM) and Vmax (5.88 µmol/min) for HRP@Alg-CoFe2O4, indicating enhanced catalytic efficiency with reduced substrate affinity. The immobilized enzyme exhibited superior tolerance to organic solvents, retaining 149% activity in n-hexane. In addition, it retained 71% activity after 10 cycles and 74% after 8 weeks of storage at 4 °C, outperforming free HRP. Optimal conditions shifted from pH 6.5 to 7.0 and from 50 to 60 °C, reflecting improved environmental resilience. This study highlights HRP@Alg-CoFe2O4 as a robust biocatalyst, offering promising applications in wastewater treatment and industrial bioprocesses.

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.

Production of alkaline lipase by Aspergillus terreus AUMC 15762 for laundry application

Lipases are extraordinarily critical co-factor-independent enzymes with profound economic consequences. They are utilized extensively in production of fine chemicals, food, textile, pulp and paper, laundry, and biodiesel sectors. In the current study, the lipolytic activity of 141 fungal isolates-representing 21 genera and 38 species-that were isolated from samples of desert soil gathered from the Governorates of Sohag, Qena, and Aswan were examined. Of the 74 isolates showed positive lipase activity, 40 were high lipase producers. In terms of lipase production, Aspergillus terreus AUMC 15762 was the most effective strain. To enhance the synthesis of lipase from Aspergillus terreus AUMC 15762, Plackett-Burman design (PBD) was employed. For the maximal amount of lipase synthesis (103.3 U/mL), ammonium sulphate was required after three days at 25 °C, pH 4.0, and 3.0 g/L. Through the use of Trilite MA 12 anion exchanger and Sephadex G-100 column chromatography, lipase was purified 17.79 times and achieved 64.714 kDa molecular weight on SDS-PAGE. The highest possible specific activity of 3867.85 ± 214.28 U/mg was attained at pH 8.0 and 40 °C. The addition of KCl and ZnSO4 raised the lipase specific activity by 115.42%. Km of 19.0 mg/mL and Vmax of 1000 μmol/min were determined for the pure lipase. The effects of 20 U/mL pure lipase on corn and olive oily spots were examined in this work at pH 8.0 and 40 °C. The pure lipase completely removed oil contamination from fiber surfaces, as evidenced by the oily spots' separation from the white cotton textiles after 60 min. This work offers a lipase produced from Aspergillus terreus species that showed promise for industrial laundry applications.

Improving the Long-term Enantioselectivity of a Silicon-Carbon Bond-Forming Enzyme

Enantioselectivity is a key advantage of enzymatic catalysis. Understanding the most important factors influencing enantioselectivity necessitates thorough investigation for each specific enzyme. In this study, we explore various approaches to optimize reaction conditions for organosilicon production using an immobilized Cytochrome C recently tailored via directed evolution. Over extended reactions, this enzyme experiences a loss of enantioselectivity. Mass spectrometry (MS) revealed covalent modifications on the enzyme, but mutating the respective amino acids did not restore enantioselectivity. Nuclear magnetic resonance (NMR), along with a detailed comparison of the influence of reaction components such as cosolvents and reducing agents, indicated significant conformational changes in the presence of the diazo ester substrate. Additionally, we identified sodium ascorbate as a suitable and milder reducing agent compared to the previously used sodium dithionite, ensuring anaerobic conditions for silicon-carbon bond formation. Ultimately, maintaining a high enzyme-to-substrate ratio in the reaction was found to be crucial for achieving high enantiomeric purity of the organosilicon product over four days in sequential, repetitive batch reactions, thus improving the previously established reaction system. The methods and findings presented here are particularly valuable for addressing enantioselectivity issues in other enzymes that operate with diazo compounds as the substrates in carbene-transfer reactions.

Discovery, design, and engineering of enzymes based on molecular retrobiosynthesis

Biosynthesis-a process utilizing biological systems to synthesize chemical compounds-has emerged as a revolutionary solution to 21st-century challenges due to its environmental sustainability, scalability, and high stereoselectivity and regioselectivity. Recent advancements in artificial intelligence (AI) are accelerating biosynthesis by enabling intelligent design, construction, and optimization of enzymatic reactions and biological systems. We first introduce the molecular retrosynthesis route planning in biochemical pathway design, including single-step retrosynthesis algorithms and AI-based chemical retrosynthesis route design tools. We highlight the advantages and challenges of large language models in addressing the sparsity of chemical data. Furthermore, we review enzyme discovery methods based on sequence and structure alignment techniques. Breakthroughs in AI-based structural prediction methods are expected to significantly improve the accuracy of enzyme discovery. We also summarize methods for de novo enzyme generation for nonnatural or orphan reactions, focusing on AI-based enzyme functional annotation and enzyme discovery techniques based on reaction or small molecule similarity. Turning to enzyme engineering, we discuss strategies to improve enzyme thermostability, solubility, and activity, as well as the applications of AI in these fields. The shift from traditional experiment-driven models to data-driven and computationally driven intelligent models is already underway. Finally, we present potential challenges and provide a perspective on future research directions. We envision expanded applications of biocatalysis in drug development, green chemistry, and complex molecule synthesis.

Immobilisation for a stable biocatalyst application

This publication highlights the importance of immobilisation in obtaining stable biocatalysts. It is a review of the main immobilisation methods with their advantages and disadvantages. A distinction is made between methods that require a support (adsorption, covalent binding, binding via transition metals, entrapment/encapsulation) and those that do not (cross-linking, immobilisation in a reactor volume). The main characteristics that a material should have in order to be a suitable carrier for enzymes and the most popular carrier groups are discussed. The paper also highlights the factors that should be considered when designing an immobilisation methodology and the main parameters that characterise the immobilisation process. Attention is also given to the selection of a suitable reactor solution.

Engineering high-activity crosslinked enzyme aggregates via SpyCatcher/SpyTag-mediated self-assembly

Crosslinked Enzyme Aggregates (CLEAs) are favored for their operational stability and recyclability. However, the traditional CLEAs preparation may distort the enzyme's active site and reduce activity. Therefore, we developed a universally applicable crosslinked SpyCatcher scaffold system designed for the facile preparation of CLEAs. Four lysine residues were introduced to the N-terminus of SpyCatcher to enhance the crosslinking selectivity with glutaraldehyde. This scaffold subsequently enables the assembly of enzymes through the specific binding affinity between SpyTag and SpyCatcher. By precipitating SpyCatcher with (NH4)2SO4 at a 1:2 (v/v) ratio at 4 °C for 1 h, followed by crosslinking with glutaraldehyde at 25 °C and 100 rpm for 3 h, the SpyCatcher scaffold achieved a crosslinking efficiency exceeding 90 %. Utilizing this approach for the immobilization of SpyTaged enzymes to construct xylanase-CLEAs (X-CLEAs) and cellulase-CLEAs (C-CLEAs) highlighted the accurate construction the enzyme complex. Furthermore, C-CLEAs retained approximately 90 % activity after 3 cycles and over 50 % activity after 10 cycles, demonstrating good operational stability and reusability. C-CLEAs achieved a 1.6-fold more reducing sugars in corn stover hydrolysis compared to free enzymes. This suggests that the close proximity within CLEAs provided an advantage for the enzymatic cascade reaction, highlighting the potential application of CLEAs in various fields.

A novel alternative fate for shrimp fishery wastes as active ingredients in ecofriendly antifouling paints

This study addresses two environmental issues: the fate of fisheries organic wastes and the marine biofouling control. Marine biofouling continues to pose a significant environmental and economic burden, with existing solutions often being environmentally toxic or prohibitively expensive. Natural products, such as enzymes, have emerged as promising alternatives. Shrimp processing wastes are usually dumped to the environment, although they constitute an important source of marine enzymes. In this context, the present study investigates the potential of enzymatic extract derived from shrimp processing waste as an antifouling agent. We focused on the performance and stability of proteolytic enzymes within the extract under various conditions: exposure to seawater (static and dynamic) over time, and resistance to organic solvents. Additionally, we explored field trials using antifouling paints formulated with shrimp extract and we investigated a versatile and simple technology for extract immobilization. The results demonstrate that proteolytic activity in the shrimp extract remained stable over time in seawater and when exposed to organic solvents. Paints containing this extract completely inhibited macrofouling attachment for 7 months. Interestingly, control panels with deactivated enzymes exhibited macroalgae colonization but also showed reduced macroinvertebrate attachment. This suggests that additional compounds within the extract may have antifouling properties. We successfully produced nanocapsules of alginate-chitosan containing the shrimp extract using electrohydrodynamic atomization. While these nanocapsules show promise, further optimization is required. Overall, this study presents encouraging findings for the use of shrimp waste extract in antifouling paint formulations. This approach offers a potentially low-cost and environmentally friendly solution to the biofouling problem.

Rapid Colorimetric Detection of Sulfite in Red Wine Using Alginate-Copper Laccase Nanozyme with Smartphone as an Optical Readout

Compared with the conventional analytical methods, nanozyme-based colorimetric sensors offer simpler and more accessible solutions for point-of-need food safety monitoring. Herein, Alginate-Cu (AlgCu) is reported as a robust laccase mimetic nanozyme for the colorimetric detection of sulfite in red wine, a common preservative in winemaking. AlgCu represents a rational design of nanozymes where the multifunctional group alginate is used as a coordination environment for the Cu catalytic center, mimicking the amino acids microenvironment in the natural laccase. The laccase activity of the AlgCu is evaluated using 2,4-dichlorophenol as a model substrate, where its oxidized product reacts with 4-aminoantipyrine, forming a reddish-pink compound with an absorption peak at 510 nm. The result showed that the AlgCu exhibited 32.81% higher laccase activity than pristine copper NPs, highlighting the role of a coordination environment in improving catalytic activity. The addition of sulfite decreased the intensity of the catalytic chromogenic product, confirming that sulfite inhibited the laccase mimetic activity of AlgCu. The observed inhibition is linearly related to the sulfite concentration from 2 to 100 μM (R 2 = 0.996), enabling the detection of sulfite down to 0.78 μM. Furthermore, a sulfite concentration down to 4.9 μM could be detected by integrating the colorimetric assay with smartphone color readouts. Analysis of sulfite-spiked red wine samples gave recoveries between 96 and 106%. Overall, the obtained analytical figures of merits signify AlgCu as a robust nanozyme-based colorimetric chemosensor suitable for a point-of-need application in wine quality control and food safety monitoring in general.

Biofunctionalization of Magneto-Plasmonic Fe3O4@SiO2-NH2-Au Heterostructures with the Cellulase from Trichoderma reesei

The study focuses on the synthesis of Fe3O4@SiO2-NH2-Au heterostructures with magneto-plasmonic properties composed of well-defined cubic Fe3O4 cores (79 nm) covered with 10 nm silica shell and gold nanoparticles (8 nm) fabricated on silica shell. The surface-anchored MHDA (16-mercaptohexadecanoic acid) linker facilitated cellulase bioconjugation, which was confirmed through Raman spectroscopy. The presence of gold nanoparticle islands on the heterostructure enabled surface-enhanced Raman scattering (SERS), demonstrating the potential for bioactive substance identification. Immobilization of cellulase allowed for pH enhancement and enzyme thermal stability. The optimal pH shifted from 4.0 (free enzyme) to 6.0 while thermal stability increased by 20 °C. The immobilized cellulase kept its 49% activity after five hydrolysis cycles, compared to significantly lower activity for free cellulase. The proposed heterostructures for cellulase immobilization demonstrate potential for practical applications.

Electrosynthesis of Mussel-inspired Adhesive Polymers as a Novel Class of Transient Enzyme Stabilizers

Multifunctional ortho-quinones are required for the formation of thiol-catechol-connectivities (TCC) but can be delicate to handle. We present the electrochemical oxidation of the dipeptide DiDOPA, achieving up to 92 % conversion efficiency of the catechols to ortho-quinones. Graphite and stainless steel could be employed as cost-efficient electrodes. The electrochemical activation yields quinone-solutions, which are free of undesired reactive compounds and eliminates the challenging step of isolating the reactive quinones. The DiDOPA quinones were employed in polyaddition reactions with multi-thiols, forming oligomers that functioned as transient enzyme stabilizers (TES). These TCC-TES-additives improved the thermal stability and the activity of tyrosinase in heat stress assays.

Design of enzyme immobilized zwitterionic copolymer nanogels and its size effect on electrochemical reaction

For enzyme-based electrochemical devices, an improvement in electron transfer between the enzyme and electrode is important. Thus, we developed a nano-scaled hydrogel that includes an electron mediator and enzyme to realize nano-sized effects that enhance the functions. Three different chain lengths (short, medium, and long) of copolymers composed of 2-methacryloyloxyethyl phosphorylcholine (MPC) and methacrylic acid N-hydroxysuccinimide ester (MNHS; poly(MPC-co-MNHS), PMS) were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The PMS nanogels can bind to the amino ferrocene (AFc) of the electron mediator and glucose oxidase (GOD) as a catalyst. The mono-dispersive PMS nanogels approximately 200-250 nm in size bound with AFc were prepared with different polymer chain lengths and amounts of AFc (PMMFcX_Y%, X= 'degree of polymerization, 50, 75, 100' and Y= 'AFc feeding ratio against the amount of NHS group in the polymer chain, 50 %, 100 %'). The size of PMMFcX_Y% could be controlled by changing degree of polymerization or AFc feeding ratio. After the modification of GOD to PMMFcX_Y%, their size increased slightly from the original size (ca. 200-250 nm) to approximately 250-300 nm. The catalytic activity of nanogel in dispersed system was higher than that of microgel, indicating that nanogels could improve glucose transport in hydrogel layer. Compared to the catalytic reaction of the PMMFc 75_50 %-GOD nanogel-modified electrodes with that of microgel modified electrode, the current response was improved by decreasing the nanogel size, as evaluated by electrochemical measurements. These results revealed that the smaller nanogels could improve both glucose transport and electron transfer via mediator by smaller size, resulting higher efficiency of enzyme immobilized electrode.

One-pot preparation of V-type porous starch by thermal-stable amylase hydrolysis of normal maize starch in hot aqueous ethanol solution

The V-type porous starch (VPS) displays remarkable adsorption capability, and has potential for encapsulating guest compounds within its unique single helical cavity. In this investigation, VPS was produced via a "one-pot method" utilizing thermostable α-amylase in a hot ethanol solution. The study demonstrates that the activity of thermostable α-amylase remains high, reaching up to 86 % when employing a 40-50 % ethanol concentration, and up to 74 % with ≤70 % ethanol concentration. Furthermore, the enzyme exhibits robust stability at 90 °C for up to 10 h of reaction time. The resultant VPS exhibits enhanced V-type crystallinity and superior adsorption capacity compared to conventional A-type porous starch (APS). Notably, the hydrolysis of normal maize starch (NMS) by thermostable α-amylase in a 50 % ethanol solution at 90 °C yields 49.36 % VPS, which manifests a densely porous distributed structure. Additionally, the VPS is characterized by superior oil adsorption capacity (253.11 %), specific surface area (38.89 m2/g), and total pore volume (0.147 cm3/g).

In-depth recognition of mixed surfactants maintaining the enzymatic activity of cellulases through stabilization of their spatial structures

Mixed surfactants improve the enzymatic hydrolysis of lignocellulosic substrates by enhancing cellulase stability against heat, pH, shear, and air-liquid interface stress. Under conditions of multiple factorial stresses (50 °C, pH 4.8, 180 rpm, and 15.5 cm2 air-liquid interface), cellulase with ternary surfactants (Tween 60/Triton X-114/CTAB, the molar ratio 14:5.5:1) retained 84 % of its activity after 48 h of incubation, representing 1.15 and 1.29 folds that of the cellulase activity with the single Tween 60 and with no surfactants, respectively. This is attributed to the fact that ternary surfactants possess better rheology modulation and air-liquid interface competitiveness. In addition, the computational approach demonstrated that the ternary surfactants were capable of forming stronger hydrophobic and hydrogen-bond interactions with cellulase enzymes, thus maintaining its secondary structure and preventing the detrimental α-helix to β-sheet transformation known to compromise cellulase activity. This synergy offers valuable insights into surfactant-cellulase interactions and supports efficient enzymatic hydrolysis in biorefineries.

Tailored Enzymes for Difructose Anhydrides: From Biosynthesis to Degradation

Difructose anhydrides (DFAs), distinctive cyclic disaccharides mainly naturally produced by heating (caramelization), serve as potential candidates of functional sugars that modern humans consume on a daily basis due to their remarkable physiological effects. This review explores the complex domain of specialized enzymes implicated in the metabolism of DFAs, covering the entire process from biosynthesis to degradation. We provide a detailed examination of the enzymes responsible for DFA formation and degradation, specifically those classified within the GH91, GH32, and GH172 glycoside hydrolase families. Furthermore, the evolutionary relationships among the related enzymes were systematically analyzed. Subsequently, the underlying enzymatic mechanisms that drive DFAs' metabolism were elucidated, and key insights into the intricate interplay between enzyme structure and function were unveiled. Additionally, innovative strategies for enzyme engineering were discussed, aimed at improving thermostability, enhancing catalytic activity, and altering catalytic function. Finally, the applications of the related enzymes were comprehensively summarized with a focus on their product yields, conversion rates, and methods for product purification. Here, the review presents a comprehensive investigation into enzymatic degradation and biosynthesis pathways of DFAs.

In-situ nanozyme catalytic amplification coupled with a universal antibody orientation strategy based electrochemical immunosensor for AD-related biomarker

An in-situ nanozyme signal tag combined with a DNA-mediated universal antibody-oriented strategy was proposed to establish a high-performance immunosensing platform for Alzheimer's disease (AD)-related biomarker detection. Briefly, a Zr-based metal-organic framework (MOF) with peroxidase (POD)-like activity was synthesized to encapsulating the electroactive molecule methylene blue (MB), and subsequently modified with a layer of gold nanoparticles on its surface. This led to the creation of double POD-like activity nanozymes surrounding the MB molecule to form a nanozyme signal tag. A large number of hydroxyl radicals were generated by the nanozyme signal tag with the help of H2O2, which catalyzed MB molecules in situ to achieve efficient signal amplification. Subsequently, a DNA-aptamer-mediated universal antibody-oriented strategy was proposed to enhance the binding efficiency for the antigen (target). Meanwhile, a poly adenine was incorporated at the end of the aptamer, facilitating binding to the gold electrode and providing anti-fouling properties due to the hydrophilicity of the phosphate group. Under optimal conditions, this platform was successfully employed for highly sensitive detection of AD-associated tau protein and BACE1, achieving limits of detection with concentrations of 3.34 fg/mL and 1.67 fg/mL, respectively. It is worth mentioning that in the tau immunosensing mode, 20 clinical samples from volunteers of varying ages were analyzed, revealing significantly higher tau expression levels in the blood samples of elderly volunteers compared to young volunteers. This suggests that the developed strategy holds great promise for early AD diagnosis.

Sulfasalazine-Loaded Copper-Tannic Acid Coordination Nanozyme Enables ROS Scavenging and Immunomodulation for Inflammatory Bowel Disease Therapy

Inflammatory bowel disease (IBD) is associated with elevated levels of reactive oxygen species (ROS) and an increased expression of proinflammatory cytokines. Anti-inflammatory drugs, monoclonal antibodies, and immunomodulators are commonly employed to control the inflammatory response in the management of IBD. Here, a copper and tannic acid (TA) coordination nanozyme (CuTA) loaded with sulfasalazine (SSZ-CuTA) is synthesized for the treatment of IBD by simultaneous scavenging ROS and immunosuppression. The CuTA exhibits both dismutase-like activity and catalase-like activity, making it efficient at scavenging ROS. These nanozymes can efficiently traverse gastric acid and subsequently exert their effects within the intestinal tract. It is verified that SSZ-CuTA can restore intestinal mucosal and goblet cells to a healthy state by effectively eliminating ROS and reducing the pro-inflammatory factors in a mouse IBD model. Overall, the SSZ-CuTA will offer a promising alternative treatment for patients suffering from IBD where excessive ROS and high inflammation coexist.

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.

Semi-rational design in simultaneous improvement of thermostability and activity of β-1,3-glucanase from Alkalihalobacillus clausii KSMK16

Endo-β-1,3-glucanase (β-1,3-GA) is a key enzyme capable of acting on the β-1,3-glycosidic bond of β-1,3-glucan, resulting in the production of β-1,3-gluco-oligosaccharides with higher water solubility. Higher temperatures are beneficial for curdlan hydrolysis; however, low enzymatic activity and thermal stability limit their applicability. In this study, a mutant library of Endo-β-1,3-glucanase (AC-GA) derived from Alkalihalobacillus clausii KSM-K16 was constructed by a semi-rational design using amino-acid-based multiple sequence alignment and protein structure-based computer-aided engineering. The best combination mutant (S52T/M120L) was screened through ordered recombination mutations, which showed a 24.88 % increase in specific enzyme activity over the wild-type. The melting temperature (Tm) value, an enzyme protein denaturation temperature, was raised to 82.99 °C from 78.60 of the wild type. In comparison, the Km for hydrolysis of curdlan by S52T/M120L was reduced by 12.1 %, while the kcat was increased by 59.39 %, thus leading to a higher catalytic efficiency (kcat/Km, 227.73 vs 125.46 mL·s-1·mg-1). Molecular dynamics (MD) simulations showed that mutations resulted in a reduction in the overall flexibility of the enzyme, an increase in rigidity, and a more stable structure. An increase in the hydrophobic network at the entrance of the substrate increases the accessibility of the substrate to the enzyme, resulting in increased enzyme activity. High-efficiency mutants have potential industrial applications in the enzymatic preparation of β-1,3-gluco-oligosaccharides.

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.

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.

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.

Adaptability to the environment of protease by secondary structure changes and application to enzyme-selective hydrolysis

The reactions involving enzymes are significantly influenced by various environmental factors. Clarity of how the activity and structure of proteases impact their function is crucial for more efficient application of enzymes as a tool. The impact of temperature, pH, and ionic strength on changes in protease activity, secondary structure, and protein conformation during enzymatic hydrolysis were investigated in this study. The enzymatic activity and secondary structure of acid-base protease were found to undergo significant modifications under different physical conditions, as demonstrated by UV spectrophotometry and FTIR spectroscopy analysis. Specifically, variations in α-helix and β-fold content were observed to correlate with changes in enzyme activity. Molecular simulation analysis revealed that physical conditions have varying effects on the protease, particularly influencing enzyme activity and secondary structure. Evaluation of the proteases indicated alterations in both enzyme activity and structure. This treatment selectively hydrolyzed β-lactoglobulin and reduced sensitization. These findings offer novel perspectives on the functionalities and regulatory mechanisms of proteases, as well as potential industrial applications.

Boosting Fructosyl Transferase's Thermostability and Catalytic Performance for Highly Efficient Fructooligosaccharides (FOS) Production

Achieving enzymatic food processing at high substrate concentrations can significantly enhance production efficiency; however, related studies are notably insufficient. This study focused on the enzymatic synthesis of fructooligosaccharides (FOS) at high temperature and high substrate concentration. Results revealed that increased viscosity and limited substrate solubility in high-concentration systems could be alleviated by raising the reaction temperature, provided it aligned with the enzyme's thermostability. Further analysis of enzyme thermostability in real sucrose solutions demonstrates that the enzyme's thermostability was remarkedly improved at higher sucrose concentrations, evidenced by a 10.3 °C increase in melting temperature (Tm) in an 800 g/L sucrose solution. Building upon these findings, we developed a novel method for enzymatic FOS synthesis at elevated temperatures and high sucrose concentrations. Compared to existing commercial methods, the initial transglycosylation rate and volumetric productivity for FOS synthesis increased by 155.9% and 113.5%, respectively, at 65 °C in an 800 g/L sucrose solution. This study underscores the pivotal role of substrate concentration, incubation temperature, and the enzyme's actual status in advancing enzyme-catalyzed processes and demonstrates the potential of enzymatic applications in enhancing food processing technologies, providing innovative strategies for the food industry.

Tuning almond lipase features by the buffer used during immobilization: The apparent biocatalysts stability depends on the immobilization and inactivation buffers and the substrate utilized

The lipase from Prunus dulcis almonds was inactivated under different conditions. At pH 5 and 9, enzyme stability remained similar under the different studied buffers. However, when the inactivation was performed at pH 7, there were some clear differences on enzyme stability depending on the buffer used. The enzyme was more stable in Gly than when Tris was employed for inactivation. Then, the enzyme was immobilized on methacrylate beads coated with octadecyl groups at pH 7 in the presence of Gly, Tris, phosphate and HEPES. Its activity was assayed versus triacetin and S-methyl mandelate. The biocatalyst prepared in phosphate was more active versus S-methyl mandelate, while the other ones were more active versus triacetin. The immobilized enzyme stability at pH 7 depends on the buffer used for enzyme immobilization. The buffer used in the inactivation and the substrate used determined the activity. For example, glycine was the buffer that promoted the lowest or the highest stabilities depending on the substrate used to quantify the activities.

Biocatalytic PEI-PSS membranes through aqueous phase separation: influence of casting solution pH and operational temperature

Biocatalytic membranes combine the separation properties of membranes and the catalytic abilities of enzymes, holding great promise for industries where both purification and conversion are required. In this work, polyelectrolyte complex membranes incorporated with lysozyme were prepared using polyethyleneimine (PEI) and poly(sodium 4-styrenesulfonate) (PSS) through a one-step and mild pH shift aqueous phase separation (APS) approach. The effects of lysozyme addition and casting solution pH on the membrane properties were studied. All the membranes, both with and without added lysozyme, exhibited asymmetric structures with relatively dense top surfaces and porous cross-sections with finger-like macrovoids. The incorporation of lysozyme did not significantly influence the structure and permeability of the formed membranes. The PEI-PSS biocatalytic membranes exhibited temperature dependent enzymatic activity. The activity strongly increased with increased operational temperature, with the highest activity of 4.30 ± 0.15 U cm-2 at 45 °C. This indicates a responsive effect, where a higher temperature leads to some swelling of the polyelectrolyte complex membrane, making the enzyme more accessible to the used substrate. Moreover, the biocatalytic membranes demonstrate desirable enzymatic stability, maintaining 60% activity even after 60 days of storage. This study validates the potential of the water-based APS process as a straightforward approach for integrating enzymes into responsive biocatalytic membranes.

A review on the immobilization of bromelain

This review shows the endeavors performed to prepare immobilized formulations of bromelain extract, usually from pineapple, and their use in diverse applications. This extract has a potent proteolytic component that is based on thiol proteases, which differ depending on the location on the fruit. Stem and fruit are the areas where higher activity is found. The edible origin of this enzyme is one of the features that determines the applications of the immobilized bromelain to a more significant degree. The enzyme has been immobilized on a wide diversity of supports via different strategies (covalent bonds, ion exchange), and also forming ex novo solids (nanoflowers, CLEAs, trapping in alginate beads, etc.). The use of preexisting nanoparticles as immobilization supports is relevant, as this facilitates one of the main applications of the immobilized enzyme, in therapeutic applications (as wound dressing and healing components, antibacterial or anticancer, mucus mobility control, etc.). A curiosity is the immobilization of this enzyme on spores of probiotic microorganisms via adsorption, in order to have a perfect in vivo compatibility. Other outstanding applications of the immobilized enzyme are in the stabilization of wine versus haze during storage, mainly when immobilized on chitosan. Curiously, the immobilized bromelain has been scarcely applied in the production of bioactive peptides.

Simple Sol-Gel Protein Stabilization toward Rainbow and White Lighting Devices

Fluorescent proteins (FPs) are heralded as a paradigm of sustainable materials for photonics/optoelectronics. However, their stabilization under non-physiological environments and/or harsh operation conditions is the major challenge. Among the FP-stabilization methods, classical sol-gel is the most effective, but less versatile, as most of the proteins/enzymes are easily degraded due to the need of multi-step processes, surfactants, and mixed water/organic solvents in extreme pH. Herein, sol-gel chemistry with archetypal FPs (mGreenLantern; mCherry) is revisited, simplifying the method by one-pot, surfactant-free, and aqueous media (phosphate buffer saline pH = 7.4). The synthesis mechanism involves the direct reaction of the carboxylic groups at the FP surface with the silica precursor, generating a positively charged FP intermediate that acts as a seed for the formation of size-controlled mesoporous FP@SiO2 nanoparticles. Green-/red-emissive (single-FP component) and dual-emissive (multi-FPs component; kinetic studies not required) FP@SiO2 are prepared without affecting the FP photoluminescence and stabilities (>6 months) under dry storage and organic solvent suspensions. Finally, FP@SiO2 color filters are applied to rainbow and white bio-hybrid light-emitting diodes featuring up to 15-fold enhanced stabilities without reducing luminous efficacy compared to references with native FPs. Overall, an easy, versatile, and effective FP-stabilization method is demonstrated in FP@SiO2 toward sustainable protein lighting.

Stability of Protein Pharmaceuticals: Recent Advances

There have been significant advances in the formulation and stabilization of proteins in the liquid state over the past years since our previous review. Our mechanistic understanding of protein-excipient interactions has increased, allowing one to develop formulations in a more rational fashion. The field has moved towards more complex and challenging formulations, such as high concentration formulations to allow for subcutaneous administration and co-formulation. While much of the published work has focused on mAbs, the principles appear to apply to any therapeutic protein, although mAbs clearly have some distinctive features. In this review, we first discuss chemical degradation reactions. This is followed by a section on physical instability issues. Then, more specific topics are addressed: instability induced by interactions with interfaces, predictive methods for physical stability and interplay between chemical and physical instability. The final parts are devoted to discussions how all the above impacts (co-)formulation strategies, in particular for high protein concentration solutions.'

Enzyme stability in polymer hydrogel-enzyme hybrid nanocarrier containing phosphorylcholine group

Enzymes are biological catalysts with good biocompatibility and high efficiency and have been widely used in many fields, such as wastewater treatment, biosensors, and the medical industry. However, their inherently low stability under conditions of practical use limits further applications. Zwitterionic polymers possessing a pair of oppositely charged groups in their repeating units can increase protein stability because of their good biocompatibility and high water content. In this study, zwitterionic copolymer nanogels comprising poly(2-methacryloyloxyethyl phosphorylcholine (MPC)-co-methacrylic acid-N-hydroxy succinimide ester (MNHS)) (PMS) were synthesized via reversible addition-fragmentation chain-transfer polymerization (RAFT). β-Galactosidase (β-gal) was post-modified within zwitterionic polymer nanogels with a covalently-bound spacer and the activity was compared with that of directly immobilized β-gal and free β-gal. Compared with direct immobilization, covalent immobilization with a spacer could reduce the structural change of β-gal, as confirmed by the circular dichroism spectra. Although the activity of β-gal decreased after immobilization, the hybrids of the β-gal immobilized nanogels, termed hybrid nanogel-enzymes, demonstrated superior stability compared to the free enzymes. The hybrid nanogel-enzymes maintained their function against inactivation by organic solvents and proteinases owing to their high water content, anti-biofouling properties, and limited mass transfer. They can also withstand protein aggregation at high temperatures and maintain their activity. Compared to direct immobilization, immobilization with a spacer resulted in a dramatic increase in the enzyme activity and a slight decrease in the stability. These results indicate that polymer nanogels containing phosphorylcholine units are promising materials for enzyme immobilization, expanding the scope of enzyme applications.

Wall-Immobilized Biocatalyst vs. Packed Bed in Miniaturized Continuous Reactors: Performances and Scale-Up

Sustainable biocatalysis syntheses have gained considerable popularity over the years. However, further optimizations - notably to reduce costs - are required if the methods are to be successfully deployed in a range of areas. As part of this drive, various enzyme immobilization strategies have been studied, alongside process intensification from batch to continuous production. The flow bioreactor portfolio mainly ranges between packed bed reactors and wall-immobilized enzyme miniaturized reactors. Because of their simplicity, packed bed reactors are the most frequently encountered at lab-scale. However, at industrial scale, the growing pressure drop induced by the increase in equipment size hampers their implementation for some applications. Wall-immobilized miniaturized reactors require less pumping power, but a new problem arises due to their reduced enzyme-loading capacity. This review starts with a presentation of the current technology portfolio and a reminder of the metrics to be applied with flow bioreactors. Then, a benchmarking of the most recent relevant works is presented. The scale-up perspectives of the various options are presented in detail, highlighting key features of industrial requirements. One of the main objectives of this review is to clarify the strategies on which future study should center to maximize the performance of wall-immobilized enzyme reactors.

Discoloration of textile dyes by spent mushroom substrate of Agaricus bisporus

The textile industry discharges up to 5 % of their dyes in aqueous effluents. Here, use of spent mushroom substrate (SMS) of commercial white button mushroom production and its aqueous extract, SMS tea, was assessed to remove textile dyes from water. A total of 30-90 % and 5-85 % of the dyes was removed after a 24 h incubation in SMS and SMS tea, respectively. Removal of malachite green and remazol brilliant blue R was similar in SMS and its tea. In contrast, removal of crystal violet, orange G, and rose bengal was higher in SMS, explained by sorption to SMS and by the role of non-water-extractable SMS components in discoloration. Heat-treating SMS and its tea, thereby inactivating enzymes, reduced dye removal to 8-58 % and 0-31 %, respectively, indicating that dyes are removed by both enzymatic and non-enzymatic activities. Together, SMS of white button mushroom production has high potential to treat textile-dye-polluted aqueous effluents.

Pharmaceutical applications of therapeutic deep eutectic systems (THEDES) in maximising drug delivery

The issue of poor solubility of active pharmaceutical ingredients (APIs) has been a salient area of investigation and novel drug delivery systems are being developed to improve the solubility of drugs, enhance their permeability and thereby their efficacy. Several techniques for solubilization enhancement of poorly soluble drugs are often employed at various stages of pharmaceutical drug product development. One such delivery system is the therapeutic deep eutectic system (THEDES), which showed great potential in the enhancement of solubility and permeability of drugs and ultimately augmenting their bioavailability. THEDES are made by mixing drugs with deep eutectic solvents (DESs) in a definite molar ratio by the hit and trial method. The DESs are a new class of green solvents which are non-toxic, cheap, easy to prepare, biodegradable and have multiple applications in the pharmaceutical industry. The terminologies such as ionic liquids (ILs), DES, THEDES, and therapeutic liquid eutectic systems (THELES) have been very much in use recently, and it is important to highlight the pharmaceutical applications of these unexplored reservoirs in drug solubilization enhancement, drug delivery routes, and in the management of various diseases. This review is aimed at discussing the components, formulation strategies, and routes of administration of THEDES that are used in developing the formulation. Also, the major pharmaceutical applications of THEDES in the treatment of various metabolic and non-metabolic diseases are reviewed.

Direct Imaging of Protein Clusters in Metal-Organic Frameworks

Protein@metal-organic frameworks (P@MOFs) prepared by coprecipitation of protein, metal ions, and organic ligands represent an effective method for protein stabilization with a wide spectrum of applications. However, the formation mechanism of P@MOFs via the coprecipitation process and the reason why proteins can retain their biological activity in the frameworks with highly concentrated metal ions remain unsettled. Here, by a combined methodology of single molecule localization microscopy and clustering analysis, we discovered that in this process enzyme molecules form clusters with metal ions and organic ligands, contributing to both the nucleation and subsequent crystal growth. We proposed that the clusters played an important role in the retention of overall enzymatic activity by sacrificing protein molecules on the cluster surface. This work offers fresh perspectives on protein behaviors in the formation of P@MOFs, inspiring future endeavors in the design and development of artificial bionanocomposites with high biological activities.

Sustainable combination of ionic liquid and deep eutectic solvent for protecting and preserving of the protein structure: The synergistic interaction of enzymes and eco-friendly hybrid ionic fluids

Hybrid ionic fluids (HIFs) are one of the emerging and fascinating sustainable solvent media, a novel environment-friendly solvent for biomolecules. The HIFs have been synthesized by combining a deep eutectic solvent (DES), an ionic liquid (IL) having a common ion. The stability and activity of hen's egg white lysozyme (Lyz) in the presence of a recently designed new class of biocompatible solvents, HIFs have been explored by UV-visible, steady-state fluorescence, circular dichroism (CD), Fourier transform infrared spectroscopy (FT-IR) along with dynamic light scattering (DLS) measurements. This work emphasizes the effect of DES synthesized by using 1:2 choline chloride and glycerol [Glyn], ILs (1-butly-3-methylimidazolium chloride [BMIM]Cl and choline acetate [Chn][Ac]) and their corresponding HIFs on the structure and functionality of Lyz. Moving forward, we also studied the secondary structure, thermal stability and enzymatic activity and thermodynamic profile of Lyz at pH = 7 in the presence of varying concentrations (0.1 to 0.5) M of [BMIM]Cl, [Chn][Ac] ILs, [Glyn] DES and [Glyn][BMIM]Cl (hybrid ionic fluid1) as well as [Glyn][Chn][Ac] (hybrid ionic fluid2). Spectroscopic results elucidate that ILs affect the activity and structural stability of Lyz, whereas the stability and activity are increased by DES and are maintained by HIFs at all the studied concentrations. Overall, the experimental results studied elucidate expressly that the properties of Lyz are maintained in the presence of hybrid ionic fluid1 while these properties are intensified in hybrid ionic fluid2. This work has elucidated expressly biocompatible green solvents in protein stability and functionality due to the alluring properties of DES, which can counteract the negative effect of ILs in HIFs.

Affinity purification/immobilization of poly histidine-tagged proteins by nickel-functionalized porous chitosan membranes

Although immobilized metal ion affinity chromatography (IMAC) is one of the most effective methods for purifying his-tagged proteins, it has limitations such as expensive commercial resins and non-specific binding of unwanted proteins to the nickel immobilized on the resin. In this study, biocompatible chitosan and porous chitosan membranes as alternative resins were synthesized for protein immobilization and purification, but finally porous chitosan membrane was selected due to its higher porosity and consequently higher nickel adsorption. Once the membrane was functionalized with nickel ions and its metal adsorption confirmed by EDS and ICP methods, it was used to immobilize and purify recombinant β-NGF as a protein model with his-tag tail in batch-fashion. Protein binding and purification were also approved by FTIR and UV-Vis spectroscopy and SDS-PAGE technique. Our results indicated that the protein of interest could bind to the nickel-functionalized porous chitosan membrane with high efficiency at pH=7. Furthermore, for protein purification, the pH value of 6 and an imidazole concentration of 750 mM were suggested for the final elution buffer. In conclusion, nickel-functionalized porous chitosan membrane could be a suitable alternative to IMAC for low cost and specific protein immobilization and purification.

Integrating Enzymes with Supramolecular Polymers for Recyclable Photobiocatalytic Catalysis

Chemical modifications of enzymes excel in the realm of enzyme engineering due to its directness, robustness, and efficiency; however, challenges persist in devising versatile and effective strategies. In this study, we introduce a supramolecular modification methodology that amalgamates a supramolecular polymer with Candida antarctica lipase B (CalB) to create supramolecular enzymes (SupEnzyme). This approach features the straightforward preparation of a supramolecular amphiphilic polymer (β-CD@SMA), which was subsequently conjugated to the enzyme, resulting in a SupEnzyme capable of self-assembly into supramolecular nanoparticles. The resulting SupEnzyme nanoparticles can form micron-scale supramolecular aggregates through supramolecular and electrostatic interactions with guest entities, thus enhancing catalyst recycling. Remarkably, these aggregates maintain 80 % activity after seven cycles, outperforming Novozym 435. Additionally, they can effectively initiate photobiocatalytic cascade reactions using guest photocatalysts. As a consequence, our SupEnzyme methodology exhibits noteworthy adaptability in enzyme modification, presenting a versatile platform for various polymer, enzyme, and biocompatible catalyst pairings, with potential applications in the fields of chemistry and biology.

Biochemical characterization of acid proteases from the stomach of palometa (Pygocentrus nattereri, Kner 1858) with potential industrial application

Pepsin is one of the major enzymes with significant importance in the food industry, biomedicines, and pharmaceutical formulations. In this work, the main objective was to biochemically characterize a pepsin-like enzymatic extract obtained from Pygocentrus nattereri, a predatory freshwater fish, focusing on their potential industrial application. The obtained extract exhibited optimal activity at 45 °C and pH 1.0-2.0. These proteases remained stable after 2 h of incubation at temperatures ranging from 0° to 45 °C and within pH range of 1.0 to 7.0. Their activity was significantly affected in presence of pepstatin A and SDS, 10 μM and 3.46 mM respectively, while EDTA and PMSF showed partial inhibitory effects. Divalent cations (Ca2+ and Mg2+) did not inhibit the proteolytic activity of the extract; in fact, it improved at a 5 mM CaCl2 concentration. As the NaCl concentration increased, the enzyme activity decreased. However, after desalination, 90 % of the activity was recovered within the tested exposure time. Besides, this extract demonstrated exceptional versatility across diverse industrial applications, including collagen extraction augmentation, IgG hydrolysis facilitation, and silver and polyester recovery from X-ray films. Our results suggest that the obtained enzymatic extract has a wide range of potential applications.

Novel Stable Protease Inhibitor from Phoenix dactylifera(L.) Flowers with Antimicrobial and Antitumoral Activities

A novel protease inhibitor isolated from date palm Phoenix dactylifera(L.) flowers (PIDF) was purified and characterized. A heat and acidic treatment step followed by ethanol precipitation and reverse-phase high-performance chromatography was applied to purify this natural protease inhibitor to homogeneity with a single band of about 19 kDa. The stability study depicted that PIDF was fully stable at 40 °C and retained 65% of its initial activity after heating at 50 °C for 24 h. Its thermal stability at 70 °C was markedly enhanced by adding calcium, bovine serum albumin, and sorbitol as well as by metal divalent cations, especially Mg2+ and Hg2+. This protease inhibitor showed high inhibitory activity against therapeutic proteases, including pepsin, trypsin, chymotrypsin, and collagenase, and acted as a potent inhibitor of some commercial microbial proteases from Aspergillus oryzae, Bacillus. sp, and Bacillus licheniformis. Moreover, a potent antibacterial spectrum against Gram (+) and Gram (-) bacterial strains and an efficient antifungal effect were observed. Its cytotoxicity toward human colorectal cancer cell LoVo and HCT-116 lines suggested that PIDF could serve as a new therapeutic target inhibiting human colorectal cancer.

Ionic liquids and deep eutectic solvents for the stabilization of biopharmaceuticals: A review

Biopharmaceuticals have allowed the control of previously untreatable diseases. However, their low solubility and stability still hinder their application, transport, and storage. Hence, researchers have applied different compounds to preserve and enhance the delivery of biopharmaceuticals, such as ionic liquids (ILs) and deep eutectic solvents (DESs). Although the biopharmaceutical industry can employ various substances for enhancing formulations, their effect will change depending on the properties of the target biomolecule and environmental conditions. Hence, this review organized the current state-of-the-art on the application of ILs and DESs to stabilize biopharmaceuticals, considering the properties of the biomolecules, ILs, and DESs classes, concentration range, types of stability, and effect. We also provided a critical discussion regarding the potential utilization of ILs and DESs in pharmaceutical formulations, considering the restrictions in this field, as well as the advantages and drawbacks of these substances for medical applications. Overall, the most applied IL and DES classes for stabilizing biopharmaceuticals were cholinium-, imidazolium-, and ammonium-based, with cholinium ILs also employed to improve their delivery. Interestingly, dilute and concentrated ILs and DESs solutions presented similar results regarding the stabilization of biopharmaceuticals. With additional investigation, ILs and DESs have the potential to overcome current challenges in biopharmaceutical formulation.

Immobilization of l-asparaginase on chitosan nanoparticles for the purpose of long-term application

Asparaginase holds significant commercial value as an enzyme in the food and pharmaceutical industries. This study examined the optimum and practical use of the l-asparaginase derived from Pseudomonas aeruginosa HR03. Specifically, the study focused on the effectiveness of the stabilized enzyme when applied to chitosan nanoparticles. The structure, size, and morphology of chitosan nanoparticles were evaluated in relation to the immobilization procedure. This assessment involved the use of several analytical techniques, including FT-IR, DLS, SEM, TEM, and EDS analysis. Subsequently, the durability of the enzyme that has been stabilized was assessed by evaluating its effectiveness under extreme temperatures of 60 and 70 °C, as well as at pH values of 3 and 12. The findings indicate that incorporating chitosan nanoparticles led to enhanced immobilization of the l-asparaginase enzyme. This improvement was observed in terms of long-term stability, stability under crucial temperature and pH conditions, as well as thermal stability. In addition, the optimum temperature increased from 40 to 50 °C, and the optimum pH increased from 8 to 9. Enzyme immobilization led to an increase in Km and a decrease in kcat compared to its free counterpart. Because of its enhanced long-term stability, l-asparaginase immobilization on chitosan nanoparticles may be a potential choice for use in industries that rely on l-asparaginase enzymes, particularly the pharmaceutical and food industries.

Cationic polyelectrolytes prevent the aggregation of l-lactate dehydrogenase under unstable conditions

Unstructured biological macromolecules have attracted attention as protein aggregation inhibitors in living cells. Some are characterized by their free structural configuration, highly charged, and water-soluble. However, the importance of these properties in inhibiting protein aggregation remains unclear. In this study, we investigated the effect of charged poly (amino acids), which mimic these properties, on aggregation of l-lactate dehydrogenase (LDH) and compared their effects to monomeric amino acids and folded proteins. LDH was stable and active at a neutral pH (~7) but formed inactive aggregates at acidic pH (< 6). Adding cationic polyelectrolytes of poly-l-lysine and poly-l-arginine suppressed the acid-induced aggregation and inactivation of LDH under acidic pH values. Adding monomeric amino acids and cationic folded proteins also prevented LDH aggregation but with lower efficacy than cationic polyelectrolytes. These results indicate that unstructured polyelectrolytes effectively stabilize unstable enzymes because they interact flexibly and multivalently with them. Our findings provide a simple method for stabilizing enzymes under unstable conditions.

β-glucosidases from Saccharomyces cerevisiae: production, protein precipitation, characterization, and application in the enzymatic hydrolysis of delignified sugarcane bagasse

β-glucosidase is an essential enzyme for the enzymatic hydrolysis of lignocellulosic biomass, as it catalyzes the final stage of cellulose breakdown, releasing glucose. This paper aims to produce β-glucosidase from Saccharomyces cerevisiae and evaluate the enzymatic degradation of delignified sugarcane bagasse. S. cerevisiae was grown in yeast peptone dextrose medium. Partial purification of the enzyme was achieved through precipitating proteins with ethanol, and the optimal activity was measured by optimizing pH and temperature. The effects of ions, glucose tolerance, and heat treatment were evaluated. Delignified sugarcane bagasse was hydrolyzed by the enzyme. β-glucosidase showed a specific activity of 14.0712 ± 0.0207 U mg-1. Partial purification showed 1.22-fold purification. The optimum pH and temperature were 6.24 and 54 °C, respectively. β-glucosidase showed tolerance to glucose, with a relative activity of 71.27 ± 0.16%. Thermostability showed a relative activity of 58.84 ± 0.91% at 90 °C. The hydrolysis of delignified sugarcane bagasse showed a conversion rate of 87.97 ± 0.10% in the presence of Zn2+, an ion that promoted the highest increase in enzymatic activity. S. cerevisiae produced an extracellular β-glucosidase with good stability at pH and temperatures conventionally applied in the hydrolysis of lignocellulosic biomass, showing viability for industrial application.

Evaluating the industrial potential of naturally occurring proteases: A focus on kinetic and thermodynamic parameters

Thermodynamic and kinetic parameters, such as enthalpy, entropy, and free energy, are crucial in evaluating enzyme stability and activity. These parameters, including the free energy of activation (ΔG#) and the Gibbs free energy of inactivation (ΔG*), are important for predicting energy requirements and reaction rates. However, relying solely on these parameters is insufficient in selecting an enzyme for industrial processes. Numerous studies have explored the measurement of thermodynamic parameters for proteases. Unfortunately, some of the definitions and calculations of key parameters such as ΔG#, ΔG*, and substrate-binding free energy have contained significant errors. In this study, these mistakes have been addressed and corrected. Additionally, a new parameter called δ, defined as the difference between ΔG* and ΔG#, has been introduced for the first time. It is argued that δ provides a more reliable measure for predicting the potential industrial application of enzymes. The highest calculated value for δ was found to be 39.6 kJ·mol-1 at 55 °C. Furthermore, this study also presents a comprehensive collection and determination of all thermodynamic and kinetic parameters for proteases, providing researchers and professionals in the field with a valuable resource to compare and understand the relationships between these parameters and the industrial potential of enzymes.

Microfluidic based continuous enzyme immobilization: A comprehensive review

Conventional techniques for enzyme immobilization suffer from suboptimal activity recovery due to insufficient enzyme loading and inadequate stability. Furthermore, these techniques are time-consuming and involve multiple steps which limit the applicability of immobilized enzymes. In contrast, the use of microfluidic devices for enzyme immobilization has garnered significant attention due to its ability to precisely control immobilization parameters, resulting in highly active immobilized enzymes. This approach offers several advantages, including reduced time and energy consumption, enhanced mass-heat transfer, and improved control over the mixing process. It maintains the superior structural configuration in immobilized form which ultimately affects the overall efficiency. The present review article comprehensively explains the design, construction, and various methods employed for enzyme immobilization using microfluidic devices. The immobilized enzymes prepared using these techniques demonstrated excellent catalytic activity, remarkable stability, and outstanding recyclability. Moreover, they have found applications in diverse areas such as biosensors, biotransformation, and bioremediation. The review article also discusses potential future developments and foresees significant challenges associated with enzyme immobilization using microfluidics, along with potential remedies. The development of this advanced technology not only paves the way for novel and innovative approaches to enzyme immobilization but also allows for the straightforward scalability of microfluidic-based techniques from an industrial standpoint.

Asymmetric Synthesis of N-Alkyl Amino Acids through a Biocatalytic Dynamic Kinetic Resolution of PEGylated N-Alkyl Amino Esters

The first examples of a practical procedure for a lipase-catalyzed dynamic kinetic resolution of PEGylated N-alkyl amino esters is reported. This method allows for the preparation of a broad range of aromatic and aliphatic enantiomerically enriched N-alkyl unnatural amino acids in up to 98% yield and 99% ee. We have found that PEGylated esters have a significant solubility advantage and improved reactivity over traditional hydrophobic lipase substrates, thereby allowing for efficient and scalable dynamic kinetic resolution (DKR) under aqueous conditions.