Dispelling the myths--biocatalysis in industrial synthesis

Design, Synthesis, and Application of Immobilized Enzymes on Artificial Porous Materials

Enzymes have been recognized as highly efficient biocatalysts, whereas characteristics such as poor stability and single reaction type greatly significantly limit their wide application. Hence, the exploitation of suitable carriers for immobilized enzymes enables the provision of a protective layer for the enzyme, with the capability of chemical and biological cascade catalysis. Among the various immobilization carriers, metal-organic frameworks (MOFs), covalent organic frameworks (COFs) and hydrogen-bonded organic frameworks (HOFs) have been emerging as a promising strategy to surpass the inherent instability and other limitations of free enzymes. Specifically, the integration of such artificial porous materials as carriers improves the stability and reusability of enzymes, while simultaneously affording a platform for multifunctional applications. Herein, this review systematically discusses the various preparation strategies and advantages of artificial porous materials, while elucidating the effects of different immobilization methods on enzyme activity. Furthermore, the innovative applications of artificial porous materials as multifunctional carriers in the field of enzyme immobilization fields such as enzyme carriers, photocatalysts, chemical catalysts and sensing are also comprehensively summarized here, thus demonstrating their multifunctional characteristics and promising applications in addressing complex biotransformation challenges.

Comparative Study of Enzymatic Lipolysis Using Nanofructosome-Coated CalB Lipase Encapsulated in Silica and Immobilized on Silica-Coated Magnetic Nanoparticles

This study evaluates the enzymatic lipolysis performance of nanofructosome-coated CalB lipase (CalB@NF) encapsulated in silica and immobilized on silica-coated magnetic nanoparticles (Si-MNP) for converting natural olive oil to oleic acid. The nanofructosome coating, composed of levan, a nanosized fructan polymer, was applied to enhance the heat and acid resistance of the CalB enzyme. To further improve functionality, CalB@NF was encapsulated in silica (CalB@NF@SiO2) or immobilized on Si-MNP using a chloropropylsilane linker. The silica-encapsulated CalB@NF (CalB@NF@SiO2) was synthesized via a sol-gel process, resulting in an average particle size of 304 nm, while the immobilized CalB@NF on Si-MNP exhibited a smaller average particle size of 58 nm. Quantitative determination of CalB in both formulations was conducted using the Bradford assay, yielding concentrations of 19.5 μg/mL for CalB@NF@SiO2 and 44.9 μg/mL for CalB@NF@Si-MNP. Enzymatic lipolysis was evaluated by measuring the production of oleic acid from natural olive oil. CalB@NF@Si-MNP achieved complete lipolysis within 3 h, whereas CalB@NF@SiO2 required 24 h to reach the same result. The lipolysis rates were 0.92 mmol/h for CalB@NF@Si-MNP and 0.21 mmol/h for CalB@NF@SiO2, indicating that CalB@NF@Si-MNP was 4.5 times faster. Regarding reusability, CalB@NF@SiO2 retained 20% more activity compared to CalB@NF@Si-MNP. While the reusability of CalB@NF@Si-MNP decreased to 76% after the first cycle, CalB@NF@SiO2 maintained nearly 100% reusability across multiple cycles. These results highlight the complementary strengths of the two formulations: CalB@NF@SiO2 offers controlled lipolysis rates, high stability, and excellent reusability, whereas CalB@NF@Si-MNP excels in rapid lipolysis. Both silica encapsulation and silica-coated magnetic nanoparticles demonstrate substantial potential for optimizing enzyme activity, stability, and reusability in diverse applications.

Smart Bioorthogonal Catalytic Factory for Glaucoma Therapy

Glaucoma is characterized by high intraocular pressure (IOP), oxidative stress, and distinct optic nerve damage. Natural enzymes have unparalleled advantages in the treatment of glaucoma due to their high efficiency, specificity, and selectivity. However, their poor stability and recoverability have constrained their application. The selection of good immobilization carriers is an effective strategy to protect natural enzymes. Here, we employ a mild room-temperature aqueous-phase enzyme immobilization technique to immobilize superoxide dismutase and catalase. Then, l-arginine is added to the pores and further modified with DSPE-mPEG to construct a bioorthogonal catalytic factory (SC@COF-L-D) with excellent biocompatibility. This strategy greatly protects the natural enzyme from inactivation and improves the operational stability. SC@COF-L-D can scavenge a large amount of reactive oxygen species to reduce oxidative/nitrative damage and activate the soluble guanylate cyclase pathway, thereby lowering the IOP for effective treatment of glaucoma. This work provides a paradigm for the design of materials for glaucoma therapy.

Compartmentalized co-immobilization of cellulase and cellobiose phosphorylase within zeolitic imidazolate framework efficiently synthesizes 1-p-Glc: Glycosylation of 18FDG

Enzymatic glycosylation is an efficient and biocompatible approach to enhance natural product bioavailability. Cellobiose phosphorylase, a novel glycosyltransferase, utilizes 1-phospho-glucose (1-p-Glc) as a glycosyl donor for regioselective glycosylation of various natural substrates. However, the high cost of 1-p-Glc limits the economic feasibility of the process. Thus, a dual-enzyme cascade system involving cellulase AcCel9A and cellobiose phosphorylase CbCBP using a co-immobilization strategy was developed to overcome this challenge. The system utilizes low-cost carboxymethyl cellulose (CMC) for continuous 1-p-Glc production, which was then used in the fluorodeoxy glucose (FDG) glycosylation to generate fluorodeoxy cellobiose (FDC), which potentially traces fungal infections. The compartmentalized co-immobilization of the two enzymes within the internal and external regions of a porous zeolitic imidazolate framework-8 (ZIF-8) carrier enhanced the overall stability of the dual-enzyme system. The immobilized enzymes retained approximately 63.3 % activity after seven reuse cycles and 74 % catalytic efficiency after 12 days of storage at room temperature. Therefore, the developed co-immobilized multi-enzyme system holds significant potential for industrial biocatalysis applications.

Exploring Enzyme Encapsulation Efficiency in MOFs Using Eco-Friendly Approaches

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

Cation effects and charge inversion contribute to the electrostatic stabilisation of protein bioconjugates in neat ionic liquids

Dispersing and stabilising proteins in ionic liquids (ILs) provides significant opportunities for green solvent-based biocatalysis, especially in industrial processes at elevated temperatures. While unmodified proteins undergo denaturation, their polymer-conjugated counterparts have been stabilised in neat ILs. However, the nature of interactions and the generality of protein-bioconjugate stabilisation in neat ILs require further understanding. Using a combination of different physio-chemical experimental tools and molecular dynamics (MD) simulations, here we investigate the dispersion and driving force for the stabilisation of bioconjugates in neat ILs. Solvent-free bioconjugates of different proteins, viz. myoglobin, α-chymotrypsin, and regenerated silk fibroin having predominant α-helical, β-sheet, and random coiled secondary structures, respectively, were prepared by electrostatic coupling with polyethylene-glycol (PEG)-based polymer-surfactant (PS). Protic IL (PIL, N-methyl-2-pyrolidonium trifluoromethane sulfonate; [NMP][OTF]) and aprotic ionic liquid (AIL, 1-methyl-3-(4-sulfobutyl)-1H-imidazol-3-ium trifluoromethane sulfonate; [MEZ][OTF]) were synthesized to study the bioconjugate dispersion. Interestingly, time-dependent polarised optical microscopy combined with transmittance measurements showed complete dispersion of all bioconjugates only in AIL. MD simulations of the PS-cCT bioconjugate were carried out in the same ILs as the experiments. The surface electrostatic potential of PS-cCT reversed from positive in PIL to negative in AIL due to overcharging by the AIL anion and lower mobility of the AIL cation. Strong screening of electrostatic potentials between two PS-cCT complexes in PIL resulted in reduced dispersion stability. Lower diffusivity of long alkyl chain [MEZ] cations of AIL leads to a depletion zone of IL ions between the two PS-cCT complexes (separation <70 Å), thus resulting in a significant negative potential between the complexes. Hence, protein bioconjugates in AIL were stabilised by a combination of surface overcharging and steric exclusion of [MEZ] cations from the space between the approaching bioconjugate complexes.

Self-Assembly-Activated Engineered Magnetic Biohybrids Loaded with Phosphotriesterase for Sustainable Decontamination and Detection of Organophosphorus Pesticides

Phosphotriesterase (PTE) biodegradation of organophosphorus pesticides (OPs) is an efficient and environmentally friendly method. However, the instability and nonreusability of free PTE become the key factors restricting its practical application. In this study, a novel cross-linked magnetic hybrid nanoflower (CLMNF) was prepared. Molecular dynamics (MD) simulations were performed to further investigate the enhanced catalytic efficiency of the enzymes. The recovery rate of enzyme activity was 298% due to the large specific surface area and metal ion activation effect. More importantly, the immobilization scheme greatly improved the stability and reuse performance of the catalyst and simplified the recovery operation. CLMNFs retained 90.32% relative activity after 5 consecutive cycles and maintained 84.8% relative activity after 30 days at 25 °C. It has a good practical application prospect in the degradation and detection of OPs. Consequently, the immobilized enzyme as a biocatalyst has the characteristics of high efficiency, stability, safety, and easy separation, establishing the key step in a biodetoxification system to control organophosphorus contamination in food and the environment.

Co-immobilization of a bi-enzymatic cascade into hierarchically porous MIL-53 for efficient 6'-sialyllactose production

6'-Sialyllactose (6'-SL), the most abundant sialylated human milk oligosaccharide, has attracted attention for its potential application in supplementary infant formulas. Herein, we report a facile strategy to construct a cascade bioreactor for the enzymatic synthesis of 6'-SL by co-immobilizing an enzymatic module consisting of CMP-sialic acid synthase and α-2,6-sialyltransferase into hierarchically porous MIL-53 (HP-MIL-53). The as-prepared HP-MIL-53 showed high enzyme immobilization capacity, reaching 226 mg g-1. Furthermore, the co-immobilized enzymes exhibited higher initial catalytic efficiency, and thermal, pH and storage stability than the free ones. Finally, the 6'-SL yield remained >80% after 13 cycles of use. We expect that HP-MIL-53 would have potential industrial applications in the enzymatic modular synthesis of 6'-SL and other glycans.

Co-immobilization of whole cells and enzymes by covalent organic framework for biocatalysis process intensification

Co-immobilization of cells and enzymes is often essential for the cascade biocatalytic processes of industrial-scale feasibility but remains a vast challenge. Herein, we create a facile co-immobilization platform integrating enzymes and cells in covalent organic frameworks (COFs) to realize the highly efficient cascade of inulinase and E. coli for bioconversion of natural products. Enzymes can be uniformly immobilized in the COF armor, which coats on the cell surface to produce cascade biocatalysts with high efficiency, stability and recyclability. Furthermore, this one-pot in situ synthesis process facilitates a gram-scale fabrication of enzyme-cell biocatalysts, which can generate a continuous-flow device conversing inulin to D-allulose, achieving space-time yield of 161.28 g L-1 d-1 and high stability (remaining >90% initial catalytic efficiency after 7 days of continuous reaction). The created platform is applied for various cells (e.g., E. coli, Yeast) and enzymes, demonstrating excellent universality. This study paves a pathway to break the bottleneck of extra- and intracellular catalysis, creates a high-performance and customizable platform for enzyme-cell cascade biomanufacturing, and expands the scope of biocatalysis process intensification.

Enhanced triolein and ethyl ferulate interesterification performance by CRL-AuNPs

This study established a Candida rugosa lipase (CRL) system to catalyze triolein and ethyl ferulate interesterification. The products were identified, and the binding mode between the substrates and CRL was predicted through molecular docking. Three methods for preparing CRL-AuNPs were proposed and characterized. It was found that the addition of 40 mL of 15 nm gold nanoparticles increased the CRL activity from 3.05 U/mg to 4.75 U/mg, but the hybridization efficiency was only 32.7 %. By using 4 mL of 0.1 mg/mL chloroauric acid, the hybridization efficiency was improved to 50.7 %, but the enzyme activity was sharply decreased. However, when the molar ratio of Mb to HAuCl4 was 0.2, the hybridization efficiency increased to 71.8 %, and the CRL activity was also enhanced to 5.98 U/mg. Under optimal conditions, the enzyme activity of CRL-AuNPs③ was maintained at 95 % after 6 repetitions and 85.6 % after 30 days at room temperature.

Covalent Organic Frameworks Based Photoenzymatic Nano-reactor for Asymmetric Dynamic Kinetic Resolution of Secondary Amines

Bio-catalysis represents a highly efficient and stereoselective method for the synthesis of valuable chiral compounds, however, the poor stability and limited reaction types of free enzymes restrict their wide application in industrial production. In this work, to overcome these problems, a multifunctional photoenzymatic nanoreactor CALB@COF-Ir was developed through the encapsulation of Candida antarctica lipase B (CALB) in a photosensitive covalent organic framework COF-Ir. This bio-nanocluster serves as efficient catalysts in asymmetric dynamic kinetic resolution (DKR) of secondary amines to give a series of chiral amines in high yields (up to 99 %) and enantioselectivities (up to 99 % ee). The well-designed COF-Ir not only acts as safety cover to prevent CALB from deactivation but promotes racemization of secondary amines via photo-induced hydrogen atom transfer (HAT) process. Photoelectric characterization and TDDFT calculation revealed that (ppy)2Ir units in COF-Ir play crucial role in this photocatalytic system which enhance its photo-redox properties through facilitating the separation between photoelectrons (e-) and holes (h+). Furthermore, the heterogeneous photoenzymatic nanoreactor could be recycled for five rounds with slight decline of catalytic reactivity.

Enzymatic Nanomotors Surviving Harsh Conditions Enabled by Metal Organic Frameworks Encapsulation

Enzyme-driven micro/nanomotors (MNMs) have demonstrated potentials in the biomedical field because of their excellent biocompatibility, versatility, and fuel bioavailability. However, the fragility of enzymes limits their practical application, because of their susceptibility to denaturation and degradation in realistic scenarios. Herein, a simple yet versatile and effective approach is reported to preserve the enzymatic activity and propulsion capability of enzymatic MNMs under various harsh conditions using metal organic frameworks (MOFs) as a protective shell. Urease can be encapsulated within the exoskeleton of zeolitic imidazolate framework-8 (ZIF-8) via biomimetic mineralization to form ZIF-8@urease (ZU-I) nanomotors that exhibit self-propulsion in the presence of urea. When exposed to harsh conditions, including high temperature, presence of proteases, and organic solvents, the ZU-I nanomotors still maintained their activity and mobility, whereas ZIF-8 with externally modified urease (ZU-O) nanomotors with externally modified urease as a control rapidly lost their motion capabilities owing to the inactivation of urease. Furthermore, ZU-I nanomotors exhibit effectively enhanced diffusion within the small intestine fluid, achieving a fourfold higher mucus penetration than the ZU-O nanomotors. The results highlight the effectiveness of using MOFs as protective shells for enzyme nano-engines, which can greatly advance the practical applications of enzymatic MNMs under realistic conditions, especially for biomedical purpose.

Biocatalytic, Stereoconvergent Alkylation of (Z/E)-Trisubstituted Silyl Enol Ethers

Alkene functionalization has garnered significant attention due to the versatile reactivity of C=C bonds. A major challenge is the selective conversion of isomeric alkenes into chiral products. Researchers have devised various biocatalytic strategies to transform isomeric alkenes into stereopure compounds; while selective, the enzymes often specifically convert one alkene isomer, thereby diminishing overall yield. To increase the overall yield, scientists have introduced additional driving forces to interconvert alkene isomers. This improves the yield of biocatalytic alkene functionalization at the cost of increased energy consumption and chemical waste. Developing a stereoconvergent enzyme for alkene functionalization offers an ideal solution, although such catalysts are rarely reported. Here we present engineered hemoproteins derived from a bacterial cytochrome P450 that efficiently catalyze the stereoconvergent α-carbonyl alkylation of isomeric silyl enol ethers, producing stereopure products. Through screening and directed evolution, we generated P450BM3 variant SCA-G2, which catalyzes stereoconvergent carbene transfer in E. coli, with high efficiency and stereoselectivity toward various Z/E mixtures of silyl enol ethers. In contrast to established stereospecific transformations that leave one isomer unreacted, SCA-G2 converts both isomers to a stereopure product. This biocatalytic approach simplifies the synthesis of chiral α-branched ketones by eliminating the need for stoichiometric chiral auxiliaries, strongly basic alkali-metal enolates, and harsh conditions, delivering products with high efficiency and excellent chemo- and stereoselectivities.

Role of pretty nanoflowers as novel versatile analytical tools for sensing in biomedical and bioanalytical applications

In recent years, an encouraging breakthrough in the synthesis of immobilized enzymes in flower-shaped called "organic-inorganic hybrid nanoflowers (hNFs)" with greatly enhanced catalytic activity and stability were reported. Although, these hNFs were discovered by accident, the enzymes exhibited highly enhanced catalytic activities and stabilities in the hNFs compared with the free and conventionally immobilized enzymes. Herein, we rationally utilized the catalytic activity of the hNFs for analytical applications. In this comprehensive review, we covered the design and use of the hNFs as novel versatile sensors for electrochemical, colorimetric/optical and immunosensors-based detection strategies in analytical perspective.

Proteases immobilized on nanomaterials for biocatalytic, environmental and biomedical applications: Advantages and drawbacks

Proteases have gained significant scientific and industrial interest due to their unique biocatalytic characteristics and broad-spectrum applications in different industries. The development of robust nanobiocatalytic systems by attaching proteases onto various nanostructured materials as fascinating and novel nanocarriers has demonstrated exceptional biocatalytic performance, substantial stability, and ease of recyclability over multiple reaction cycles under different chemical and physical conditions. Proteases immobilized on nanocarriers may be much more resistant to denaturation caused by extreme temperatures or pH values, detergents, organic solvents, and other protein denaturants than free enzymes. Immobilized proteases may present a lower inhibition. The use of non-porous materials in the immobilization prevents diffusion and steric hindrances during the binding of the substrate to the active sites of enzymes compared to immobilization onto porous materials; when using very large or solid substrates, orientation of the enzyme must always be adequate. The advantages and problems of the immobilization of proteases on nanoparticles are discussed in this review. The continuous and batch reactor operations of nanocarrier-immobilized proteases have been successfully investigated for a variety of applications in the leather, detergent, biomedical, food, and pharmaceutical industries. Information about immobilized proteases on various nanocarriers and nanomaterials has been systematically compiled here. Furthermore, different industrial applications of immobilized proteases have also been highlighted in this review.

The effects of the chemical modification on immobilized lipase features are affected by the enzyme crowding in the support

In this article, we have analyzed the interactions between enzyme crowding on a given support and its chemical modification (ethylenediamine modification via the carbodiimide route and picryl sulfonic (TNBS) modification of the primary amino groups) on the enzyme activity and stability. Lipase from Thermomyces lanuginosus (TLL) and lipase B from Candida antarctica (CALB) were immobilized on octyl-agarose beads at two very different enzyme loadings, one of them exceeding the capacity of the support, one well under this capacity. Chemical modifications of the highly loaded and lowly loaded biocatalysts gave very different results in terms of activity and stability, which could increase or decrease enzyme activity depending on the enzyme support loading. For example, both lowly loaded biocatalysts increased their activity after modification while the effect was the opposite for the highly loaded biocatalysts. Additionally, the modification with TNBS of highly loaded CALB biocatalyst increased its stability while decrease the activity.

An RNA-Cleaving DNAzyme That Requires an Organic Solvent to Function

Engineering functional nucleic acids that are active under unusual conditions will not only reveal their hidden abilities but also lay the groundwork for pursuing them for unique applications. Although many DNAzymes have been derived to catalyze diverse chemical reactions in aqueous solutions, no prior study has been set up to purposely derive DNAzymes that require an organic solvent to function. Herein, we utilized in vitro selection to isolate RNA-cleaving DNAzymes from a random-sequence DNA pool that were "compelled" to accept 35 % dimethyl sulfoxide (DMSO) as a cosolvent, via counter selection in a purely aqueous solution followed by positive selection in the same solution containing 35 % DMSO. This experiment led to the discovery of a new DNAzyme that requires 35 % DMSO for its catalytic activity and exhibits drastically reduced activity without DMSO. This DNAzyme also requires divalent metal ions for catalysis, and its activity is enhanced by monovalent ions. A minimized, more efficient DNAzyme was also derived. This work demonstrates that highly functional, organic solvent-dependent DNAzymes can be isolated from random-sequence DNA libraries via forced in vitro selection, thus expanding the capability and potential utility of catalytic DNA.

Co-Immobilization of a Multi-Enzyme Cascade: (S)-Selective Amine Transaminases, l-Amino Acid Oxidase and Catalase

An enzyme cascade was established previously consisting of a recycling system with an l-amino acid oxidase (hcLAAO4) and a catalase (hCAT) for different α-keto acid co-substrates of (S)-selective amine transaminases (ATAs) in kinetic resolutions of racemic amines. Only 1 mol % of the co-substrate was required and l-amino acids instead of α-keto acids could be applied. However, soluble enzymes cannot be reused easily. Immobilization of hcLAAO4, hCAT and the (S)-selective ATA from Vibrio fluvialis (ATA-Vfl) was addressed here. Immobilization of the enzymes together rather than on separate beads showed higher reaction rates most likely due to fast co-substrate channeling between ATA-Vfl and hcLAAO4 due to their close proximity. Co-immobilization allowed further reduction of the co-substrate amount to 0.1 mol % most likely due to a more efficient H2 O2 -removal caused by the stabilized hCAT and its proximity to hcLAAO4. Finally, the co-immobilized enzyme cascade was reused in 3 cycles of preparative kinetic resolutions to produce (R)-1-PEA with high enantiomeric purity (97.3 %ee). Further recycling was inefficient due to the instability of ATA-Vfl, while hcLAAO4 and hCAT revealed high stability. An engineered ATA-Vfl-8M was used in the co-immobilized enzyme cascade to produce (R)-1-(3-ethoxy-4-methoxyphenyl)-2-(methylsulfonyl)ethanamine, an apremilast-intermediate, with a 1,000 fold lower input of the co-substrate.

Analyzing Current Trends and Possible Strategies to Improve Sucrose Isomerases' Thermostability

Due to their ability to produce isomaltulose, sucrose isomerases are enzymes that have caught the attention of researchers and entrepreneurs since the 1950s. However, their low activity and stability at temperatures above 40 °C have been a bottleneck for their industrial application. Specifically, the instability of these enzymes has been a challenge when it comes to their use for the synthesis and manufacturing of chemicals on a practical scale. This is because industrial processes often require biocatalysts that can withstand harsh reaction conditions, like high temperatures. Since the 1980s, there have been significant advancements in the thermal stabilization engineering of enzymes. Based on the literature from the past few decades and the latest achievements in protein engineering, this article systematically describes the strategies used to enhance the thermal stability of sucrose isomerases. Additionally, from a theoretical perspective, we discuss other potential mechanisms that could be used for this purpose.

Glutaraldehyde modification of lipases immobilized on octyl agarose beads: Roles of the support enzyme loading and chemical amination of the enzyme on the final enzyme features

Lipase B from Candida antarctica (CALB) and lipase from Thermomyces lanuginosus (TLL) have been immobilized on octyl agarose at low loading and at a loading exceeding the maximum support capacity. Then, the enzymes have been treated with glutaraldehyde and inactivated at pH 7.0 in Tris-HCl, sodium phosphate and HEPES, giving different stabilities. Stabilization (depending on the buffer) of the highly loaded biocatalysts was found, very likely as a consequence of the detected intermolecular crosslinkings. This did not occur for the lowly loaded biocatalysts. Next, the enzymes were chemically aminated and then treated with glutaraldehyde. In the case of TLL, the intramolecular crosslinkings (visible by the apparent reduction of the protein size) increased enzyme stability of the lowly loaded biocatalysts, an effect that was further increased for the highly loaded biocatalysts due to intermolecular crosslinkings. Using CALB, the intramolecular crosslinkings were less intense, and the stabilization was lower, even though the intermolecular crosslinkings were quite intense for the highly loaded biocatalyst. The stabilization detected depended on the inactivation buffer. The interactions between enzyme loading and inactivating buffer on the effects of the chemical modifications suggest that the modification and inactivation studies must be performed under the target biocatalysts and conditions.

Green synthesis of stable hybrid biocatalyst using a hydrogen-bonded, π-π-stacking supramolecular assembly for electrochemical immunosensor

Rational integration of native enzymes and nanoscaffold is an efficient means to access robust biocatalyst, yet remains on-going challenges due to the trade-off between fragile enzymes and harsh assembling conditions. Here, we report a supramolecular strategy enabling the in situ fusion of fragile enzymes into a robust porous crystal. A c2-symmetric pyrene tecton with four formic acid arms is utilized as the building block to engineer this hybrid biocatalyst. The decorated formic acid arms afford the pyrene tectons high dispersibility in minute amount of organic solvent, and permit the hydrogen-bonded linkage of discrete pyrene tectons to an extended supramolecular network around an enzyme in almost organic solvent-free aqueous solution. This hybrid biocatalyst is covered by long-range ordered pore channels, which can serve as the gating to sieve the catalytic substrate and thus enhance the biocatalytic selectivity. Given the structural integration, a supramolecular biocatalyst-based electrochemical immunosensor is developed, enabling the pg/mL detection of cancer biomarker.

Designed Synthesis of Compartmented Bienzyme Biocatalysts Based on Core-Shell Zeolitic Imidazole Framework Nanostructures

For complex cascade biocatalysis, multienzyme compartmentalization helps to optimize substrate transport channels and promote the orderly and tunable progress of step reactions. Herein, a simple and general synthesis strategy is proposed for the construction of a multienzyme biocatalyst by compartmentalizing glucose oxidase and horseradish peroxidase (GOx and HRP) within core-shell zeolite imidazole frameworks (ZIF)-8@ZIF-8 nanostructures. Owing to the combined effects of biomimetic mineralization and the fine regulation of the ZIF-8 growth process, the uniform shell encloses the seed (core) surface by epitaxial growth, and the bienzyme system is accurately localized in a controlled manner. The versatility of this strategy is also reflected in ZIF-67. Meanwhile, with the ability to covalently bind divalent metal ions, lithocholic acid (LCA) is used as a competitive ligand to improve the pore structure of the ZIF from a single micropore to a hierarchical micro/mesopore network, which greatly increases mass transfer efficiency. Furthermore, the multienzyme cascade reaction is exemplified by the oxidation of o-phenylenediamine (OPD). The findings show that the bienzyme assembly strategy significantly affects the biocatalytic efficiency mainly by influencing the utilization efficiency of the intermediate (Hydrogen peroxide, H₂ O₂ ) between the step reactions. This study sheds new light on facile synthetic routes to constructing in vitro multienzyme biocatalysts.

Crystal Structure of Allantoinase from Escherichia coli BL21: A Molecular Insight into a Role of the Active Site Loops in Catalysis

Allantoinase (ALLase; EC 3.5.2.5) possesses a binuclear metal center in which two metal ions are bridged by a posttranslationally carbamylated lysine. ALLase acts as a key enzyme for the biogenesis and degradation of ureides by catalyzing the conversion of allantoin into allantoate. Biochemically, ALLase belongs to the cyclic amidohydrolase family, which also includes dihydropyrimidinase, dihydroorotase, hydantoinase (HYDase), and imidase. Previously, the crystal structure of ALLase from Escherichia coli K-12 (EcALLase-K12) was reported; however, the two active site loops crucial for substrate binding were not determined. This situation would limit further docking and protein engineering experiments. Here, we solved the crystal structure of E. coli BL21 ALLase (EcALLase-BL21) at a resolution of 2.07 Å (PDB ID 8HFD) to obtain more information for structural analyses. The structure has a classic TIM barrel fold. As compared with the previous work, the two missed active site loops in EcALLase-K12 were clearly determined in our structure of EcALLase-BL21. EcALLase-BL21 shared active site similarity with HYDase, an important biocatalyst for industrial production of semisynthetic penicillin and cephalosporins. Based on this structural comparison, we discussed the functional role of the two active site loops in EcALLase-BL21 to better understand the substrate/inhibitor binding mechanism for further biotechnological and pharmaceutical applications.

Complexed Crystal Structure of the Dihydroorotase Domain of Human CAD Protein with the Anticancer Drug 5-Fluorouracil

Dihydroorotase (DHOase) is the third enzyme in the pathway used for the biosynthesis of pyrimidine nucleotides. In mammals, DHOase is active in a trifunctional enzyme, CAD, which also carries out the activities of carbamoyl phosphate synthetase and aspartate transcarbamoylase. Prior to this study, it was unknown whether the FDA-approved clinical drug 5-fluorouracil (5-FU), which is used as an anticancer therapy, could bind to the DHOase domain of human CAD (huDHOase). Here, we identified huDHOase as a new 5-FU binding protein, thereby extending the 5-FU interactome to this human enzyme. In order to investigate where 5-FU binds to huDHOase, we solved the complexed crystal structure at 1.97 Å (PDB ID 8GVZ). The structure of huDHOase complexed with malate was also determined for the sake of comparison (PDB ID 8GW0). These two nonsubstrate ligands were bound at the active site of huDHOase. It was previously established that the substrate N-carbamoyl-L-aspartate is either bound to or moves away from the active site, but it is the loop that is extended towards (loop-in mode) or moved away (loop-out mode) from the active site. DHOase also binds to nonsubstrate ligands via the loop-out mode. In contrast to the Escherichia coli DHOase model, our complexed structures revealed that huDHOase binds to either 5-FU or malate via the loop-in mode. We further characterized the binding of 5-FU to huDHOase using site-directed mutagenesis and the fluorescence quenching method. Considering the loop-in mode, the dynamic loop in huDHOase should be a suitable drug-targeting site for further designing inhibitors and clinical chemotherapies to suppress pyrimidine biosynthesis in cancer cell lines.

Co-Enzymes with Dissimilar Stabilities: A Discussion of the Likely Biocatalyst Performance Problems and Some Potential Solutions

Enzymes have several excellent catalytic features, and the last few years have seen a revolution in biocatalysis, which has grown from using one enzyme to using multiple enzymes in cascade reactions, where the product of one enzyme reaction is the substrate for the subsequent one. However, enzyme stability remains an issue despite the many benefits of using enzymes in a catalytic system. When enzymes are exposed to harsh process conditions, deactivation occurs, which changes the activity of the enzyme, leading to an increase in reaction time to achieve a given conversion. Immobilization is a well-known strategy to improve many enzyme properties, if the immobilization is properly designed and controlled. Enzyme co-immobilization is a further step in the complexity of preparing a biocatalyst, whereby two or more enzymes are immobilized on the same particle or support. One crucial problem when designing and using co-immobilized enzymes is the possibility of using enzymes with very different stabilities. This paper discusses different scenarios using two co-immobilized enzymes of the same or differing stability. The effect on operational performance is shown via simple simulations using Michaelis–Menten equations to describe kinetics integrated with a deactivation term. Finally, some strategies for overcoming some of these problems are discussed.

Immobilization of Lipase B from Candida antarctica in Octyl-Vinyl Sulfone Agarose: Effect of the Enzyme-Support Interactions on Enzyme Activity, Specificity, Structure and Inactivation Pathway

Lipase B from Candida antarctica was immobilized on heterofunctional support octyl agarose activated with vinyl sulfone to prevent enzyme release under drastic conditions. Covalent attachment was established, but the blocking step using hexylamine, ethylenediamine or the amino acids glycine (Gly) and aspartic acid (Asp) altered the results. The activities were lower than those observed using the octyl biocatalyst, except when using ethylenediamine as blocking reagent and p-nitrophenol butyrate (pNPB) as substrate. The enzyme stability increased using these new biocatalysts at pH 7 and 9 using all blocking agents (much more significantly at pH 9), while it decreased at pH 5 except when using Gly as blocking agent. The stress inactivation of the biocatalysts decreased the enzyme activity versus three different substrates (pNPB, S-methyl mandelate and triacetin) in a relatively similar fashion. The tryptophane (Trp) fluorescence spectra were different for the biocatalysts, suggesting different enzyme conformations. However, the fluorescence spectra changes during the inactivation were not too different except for the biocatalyst blocked with Asp, suggesting that, except for this biocatalyst, the inactivation pathways may not be so different.

Locking the Ultrasound-Induced Active Conformation of Metalloenzymes in Metal-Organic Frameworks

Enhancing the enzymatic activity inside metal-organic frameworks (MOFs) is a critical challenge in chemical technology and bio-technology, which, if addressed, will broaden their scope in energy, food, environmental, and pharmaceutical industries. Here, we report a simple yet versatile and effective strategy to optimize biocatalytic activity by using MOFs to rapidly "lock" the ultrasound (US)-activated but more fragile conformation of metalloenzymes. The results demonstrate that up to 5.3-fold and 9.3-fold biocatalytic activity enhancement of the free and MOF-immobilized enzymes could be achieved compared to those without US pretreatment, respectively. Using horseradish peroxidase as a model, molecular dynamics simulation demonstrates that the improved activity of the enzyme is driven by an opened gate conformation of the heme active site, which allows more efficient substrate binding to the enzyme. The intact heme active site is confirmed by solid-state UV-vis and electron paramagnetic resonance, while the US-induced enzyme conformation change is confirmed by circular dichroism spectroscopy and Fourier-transform infrared spectroscopy. In addition, the improved activity of the biocomposites does not compromise their stability upon heating or exposure to organic solvent and a digestion cocktail. This rapid locking and immobilization strategy of the US-induced active enzyme conformation in MOFs gives rise to new possibilities for the exploitation of highly efficient biocatalysts for diverse applications.

Novel Glucosylimidazolium Ionic-Liquid-Supported Novozym 435 Catalysts - A Proof of Concept for an Acrylation Reaction

A series of novel ionic liquids based on glucose was synthesized in high yields in simple two or three-step reaction procedures. These carbohydrate-based ionic liquids were studied and compared to commercially available imidazolium-based ionic liquids as supports for Novozym 435 in the acrylation of n-butanol. A direct correlation between the availability of hydroxy groups and the overall activity as well as an enhanced recyclability of the biocatalyst has been found for the glucose-based ionic liquids.

Switch off/switch on of a cysteinyl protease as a way to preserve the active catalytic group by modification with a reversible covalent thiol modifier: Immobilization of ficin on vinyl-sulfone activated supports

The immobilization of ficin (a cysteinyl proteases) on vinyl sulfone agarose produced its almost full inactivation. It was observed that the incubation of the free and immobilized enzyme in β-mercaptoethanol produced a 20 % of enzyme activity recovery, suggesting that the inactivation due to the immobilization could be a consequence of the modification of the catalytic Cys. To prevent the enzyme inactivation during the immobilization, switching off of ficin via Cys reaction with dipyridyl-disulfide was implemented, giving a reversible disulfide bond that produced a fully inactive enzyme. The switch on of ficin activity was implemented by incubation in 1 M β-mercaptoethanol. Using this strategy to immobilize the enzyme on vinyl sulfone agarose beads, the expressed activity of the immobilized ficin could be boosted up to 80 %. The immobilized enzyme presented a thermal stabilization similar to that obtained using ficin-glyoxyl-agarose beads. This procedure may be extended to many enzymes containing critical Cys, to permit their immobilization or chemical modification.

Confining enzymes in porous organic frameworks: from synthetic strategy and characterization to healthcare applications

Enzymes are a class of natural catalysts with high efficiency, specificity, and selectivity unmatched by their synthetic counterparts and dictate a myriad of reactions that constitute various cascades in living cells. The development of suitable supports is significant for the immobilization of structurally flexible enzymes, enabling biomimetic transformation in the extracellular environment. Accordingly, porous organic frameworks, including metal organic frameworks (MOFs), covalent organic frameworks (COFs) and hydrogen-bonded organic frameworks (HOFs), have emerged as ideal supports for the immobilization of enzymes because of their structural features including ultrahigh surface area, tailorable porosity, and versatile framework compositions. Specially, organic framework-encased enzymes have shown significant enhancement in stability and reusability, and their tailorable pore opening provides a gatekeeper-like effect for guest sieving, which is beneficial for mimicking intracellular biocatalysis processes. This immobilization technique brings new insight into the development of next-generation enzyme materials and shows huge potential in healthcare applications, such as biomarker diagnosis, biostorage, and cancer and antibacterial therapies. In this review, we describe the state-of-the-art strategies for the structural immobilization of enzymes using the well-explored MOFs and burgeoning COFs and HOFs as scaffolds, with special emphasis on how these porous framework-confined technologies can provide a favorable microenvironment for mimicking natural biocatalysis. Subsequently, advanced characterization techniques for enzyme conformation, the effect of the confined microenvironment on the activity of enzymes, and the emerging healthcare applications will be surveyed.

Presenting B-DNA as macromolecular crowding agent to improve efficacy of cytochrome c under various stresses

Existence of numerous biomolecules results in biological fluids to be extremely crowded. Thus, Macromolecular crowding is an essential phenomenon to sustain active conformation of proteins in biological systems. Herein, double helical deoxyribonucleic acid (B-DNA) is presented for the first time as a biomacromolecular crowding system for sustainable packaging of cytochrome c (Cyt C). The peroxidase activity of Cyt C was investigated in the presence of various concentrations of B-DNA (from salmon milt). At an optimized concentration of 0.125 mg/mL B-DNA, an 11-fold higher catalytic activity was found than in native Cyt C with improved stability. Molecular docking and spectroscopic analyses revealed that electrostatic and H-bonding are the main interactions between DNA and Cyt C that affect the structural stability and activity of the protein. Moreover, the catalytic activity and stability of the protein were further investigated in the presence of severe process conditions by UV-visible, circular dichroism, and Fourier-transform infrared spectroscopies. Molecularly crowded Cyt C showed significantly higher activity and stability under severe environments such as high temperature (110 °C), oxidative stress, high pH (pH 10) and biological (trypsin) and chemical denaturants (urea) compared to bare Cyt C. The observed results support the suitability of DNA-based macromolecular crowding media as a viable and effective stabilizer of proteins against multiple stresses.

A review on the immobilization of pepsin: A Lys-poor enzyme that is unstable at alkaline pH values

Pepsin is a protease used in many different applications, and in many instances, it is utilized in an immobilized form to prevent contamination of the reaction product. This enzyme has two peculiarities that make its immobilization complex. The first one is related to the poor presence of primary amino groups on its surface (just one Lys and the terminal amino group). The second one is its poor stability at alkaline pH values. Both features make the immobilization of this enzyme to be considered a complicated goal, as most of the immobilization protocols utilize primary amino groups for immobilization. This review presents some of the attempts to get immobilized pepsin biocatalyst and their applications. The high density of anionic groups (Asp and Glu) make the anion exchange of the enzyme simpler, but this makes many of the strategies utilized to immobilize the enzyme (e.g., amino-glutaraldehyde supports) more related to a mixed ion exchange/hydrophobic adsorption than to real covalent immobilization. Finally, we propose some possibilities that can permit not only the covalent immobilization of this enzyme, but also their stabilization via multipoint covalent attachment.

Influence of the Greater Protein Environment on the Electrostatic Potential in Metalloenzyme Active Sites: The Case of Formate Dehydrogenase

The Mo/W-containing metalloenzyme formate dehydrogenase (FDH) is an efficient and selective natural catalyst that reversibly converts CO₂ to formate under ambient conditions. In this study, we investigate the impact of the greater protein environment on the electrostatic potential (ESP) of the active site. To model the enzyme environment, we used a combination of classical molecular dynamics and multiscale quantum-mechanical (QM)/molecular-mechanical (MM) simulations. We leverage charge shift analysis to systematically construct QM regions and analyze the electronic environment of the active site by evaluating the degree of charge transfer between the core active site and the protein environment. The contribution of the terminal chalcogen ligand to the ESP of the metal center is substantial and dependent on the chalcogen identity, with similar, less negative ESPs for Se and S terminal chalcogens in comparison to O regardless of whether the metal is Mo or W. The orientation of the side chains and conformations of the cofactor also affect the ESP, highlighting the importance of sampling dynamic fluctuations in the protein. Overall, our observations suggest that the terminal chalcogen ligand identity plays an important role in the enzymatic activity of FDH, suggesting opportunities for a rational bioinspired catalyst design.

Design of Artificial Enzymes Bearing Several Active Centers: New Trends, Opportunities and Problems

Harnessing enzymes which possess several catalytic activities is a topic where intense research has been carried out, mainly coupled with the development of cascade reactions. This review tries to cover the different possibilities to reach this goal: enzymes with promiscuous activities, fusion enzymes, enzymes + metal catalysts (including metal nanoparticles or site-directed attached organometallic catalyst), enzymes bearing non-canonical amino acids + metal catalysts, design of enzymes bearing a second biological but artificial active center (plurizymes) by coupling enzyme modelling and directed mutagenesis and plurizymes that have been site directed modified in both or in just one active center with an irreversible inhibitor attached to an organometallic catalyst. Some examples of cascade reactions catalyzed by the enzymes bearing several catalytic activities are also described. Finally, some foreseen problems of the use of these multi-activity enzymes are described (mainly related to the balance of the catalytic activities, necessary in many instances, or the different operational stabilities of the different catalytic activities). The design of new multi-activity enzymes (e.g., plurizymes or modified plurizymes) seems to be a topic with unarguable interest, as this may link biological and non-biological activities to establish new combo-catalysis routes.

Long-Term Biocatalyst Performance: Mechanistic Prediction and Continuous Non-Isothermal Testing

The assessment of the operational stability of biocatalysts by conventional direct determination of the total turnover number (TTN), a useful indicator of lifetime biocatalyst productivity, via continuous isothermal experiments tends to be time-consuming, material-intensive, and prone to disturbances, especially in case of rather stable catalysts. In the present work, we present and validate two alternative methods for estimating the TTN of a biocatalyst for any desired operating temperature. The first method is a mechanistic approach, built upon mathematical derivation of enzyme deactivation models derived from first principles, in which TTN can be calculated from two straightforward isothermal biochemical batch measurements. The second method relies on a few non-isothermal, continuous-mode experiments in conjunction with mathematical modeling to determine the intrinsic deactivation parameters of the biocatalyst. We verify both methods on the test case of TEM-1 β-lactamase-catalyzed penicillin G (Pen G) hydrolysis. Both alternative methods provide estimates of TTN which are typically within a factor of two to five or less of the values measured directly via lengthy, costly, and error-prone conventional isothermal aging tests. Therefore, both the mechanistic approach and the non-isothermal continuous approach are extremely valuable tools to enable calculation of catalyst cost contribution in continuous processing and to eliminate underperforming candidates in search of the most stable biocatalyst.

Thermally Stable and Reusable Ceramic Encapsulated and Cross-Linked CalB Enzyme Particles for Rapid Hydrolysis and Esterification

Candida antarctica lipase B (CalB) enzyme was encapsulated and cross-linked by silica matrix to enhance its thermal stability and reusability, and demonstrated an enzymatic ability for rapid hydrolysis and esterification. Silica encapsulated CalB particles (Si-E-CPs) and silica cross-linked CalB particles (Si-CL-CPs) were prepared as a function of TEOS concentration. The particle size analysis, thermal stability, catalytic activity in different pHs, and reusability of Si-E-CPs and Si-CL-CPs were demonstrated. Furthermore, the determination of the CalB enzyme in Si-E-CPs and Si-CL-CPs was achieved by Bradford assay and TGA analysis. Enzymatic hydrolysis was performed against the p-nitrophenyl butyrate and the catalytic parameters (K_m, V_max, and K_cat) were calculated by the Michaelis–Menten equation and a Lineweaver–Burk plot. Moreover, enzymatic synthesis for benzyl benzoate was demonstrated by esterification with an acyl donor of benzoic acid and two acyl donors of benzoic anhydride. Although the conversion efficiency of Si-CL-CPs was not much higher than that of native CalB, it has an efficiency of 91% compared to native CalB and is expected to be very useful because it has high thermal and pH stability and excellent reusability.

Sources, purification, immobilization and industrial applications of microbial lipases: An overview

Microbial lipase is looking for better attention with the fast growth of enzyme proficiency and other benefits like easy, cost-effective, and reliable manufacturing. Immobilized enzymes can be used repetitively and are incapable to catalyze the reactions in the system continuously. Hydrophobic supports are utilized to immobilize enzymes when the ionic strength is low. This approach allows for the immobilization, purification, stability, and hyperactivation of lipases in a single step. The diffusion of the substrate is more advantageous on hydrophobic supports than on hydrophilic supports in the carrier. These approaches are critical to the immobilization performance of the enzyme. For enzyme immobilization, synthesis provides a higher pH value as well as greater heat stability. Using a mixture of immobilization methods, the binding force between enzymes and the support rises, reducing enzyme leakage. Lipase adsorption produces interfacial activation when it is immobilized on hydrophobic support. As a result, in the immobilization process, this procedure is primarily used for a variety of industrial applications. Microbial sources, immobilization techniques, and industrial applications in the fields of food, flavor, detergent, paper and pulp, pharmaceuticals, biodiesel, derivatives of esters and amino groups, agrochemicals, biosensor applications, cosmetics, perfumery, and bioremediation are all discussed in this review.

Facile synthesis of core\shell Fe3O4@mSiO2(Hb) and its application for organic wastewater treatment

Treatment of organic wastewater is a challenging task. Biological techniques using biocatalysts have shown their benefits in organic wastewater treatment. In this research, a novel biocatalyst was developed by encapsulation of Fe3O4 microspheres and haemoglobin (Hb) with mesoporous silica, named Fe3O4@mSiO2(Hb). Fe3O4@mSiO2(Hb) exhibited typical mesoporous characteristics (mesoporous silica), magnetic feature (Fe3O4) and peroxidase activity (Hb). The results showed that the immobilization of Hb into Fe3O4@mSiO2 did not affect its activity. In addition, Fe3O4@mSiO2(Hb) exhibited a higher efficiency in the peroxidation of aromatic compounds than free Hb. The peroxidase activity of the synthesized biocatalyst was estimated to be 120 Ug^-1, which was almost four times greater than that of previously reported immobilized Hb. Also, the Km of Fe₃O₄@mSiO₂(Hb) was similar to that of the free Hb and it was estimated to be 4.3 × 10^-4 μM, indicating that the activity of the Hb in the immobilized enzyme was not affected after immobilization. The immobilized enzyme was also found to be stable, recyclable and reusable. Taken together, these results indicate that the Fe₃O₄@mSiO₂(Hb) has good potential to be used for treating organic wastewater containing aromatic compounds. The magnetically separable novel biocatalyst developed in this study provided not only a more suitable microenvironment for retaining the activity of Hb, but also demonstrated enhanced stability and activity under unfavorable conditions.

Highly Efficient Synergistic Biocatalysis Driven by Stably Loaded Enzymes within Hierarchically Porous Iron/Cobalt Metal-Organic Framework via Biomimetic Mineralization

The integration of multimodal chemo-/bio-catalysis for efficient cascade reactions has long provided broad prospects in the field of biotechnology for ages. In this work, we describe the synthesis of a...

Biocatalysis making waves in organic chemistry

Biocatalysis has an enormous impact on chemical synthesis. The waves in which biocatalysis has developed, and in doing so changed our perception of what organic chemistry is, were reviewed 20 and 10 years ago. Here we review the consequences of these waves of development. Nowadays, hydrolases are widely used on an industrial scale for the benign synthesis of commodity and bulk chemicals and are fully developed. In addition, further enzyme classes are gaining ever increasing interest. Particularly, enzymes catalysing selective C-C-bond formation reactions and enzymes catalysing selective oxidation and reduction reactions are solving long-standing synthetic challenges in organic chemistry. Combined efforts from molecular biology, systems biology, organic chemistry and chemical engineering will establish a whole new toolbox for chemistry. Recent developments are critically reviewed.

Biocatalytic one pot three component approach: Facile synthesis, characterization, molecular modelling and hypoglycemic studies of new thiazolidinedione festooned quinoline analogues catalyzed by alkaline protease from Aspergillus niger

A novel ANAP (Aspergillus niger from alkaline protease) catalyzed one pot three component approach in the synthesis of new thiazolidinedione festooned quinoline analogues via Knoevenagel condensation and N-alkylation have been reported. The catalytic effect of enzyme was monitored and optimized by adjusting various parameters including catalyst concentration, choice of solvent and temperature. The isolated alkaline protease exhibits favorable features for the reaction response such as the shorter reaction time, simple work-up procedure, clean reaction profiles and excellent product yields through reusability of the catalyst upto five cycles. In silico molecular docking simulations were carried out to find out the effective binding affinity of the synthesized quinoline analogues 4(a-i) towards PPARγ protein (Id-2XKW). In vitro α-amylase and α-glucosidase assays were performed for hypoglycemic activity evaluation. In vivo hypoglycemic studies carried out on streptozotocin (SZT) induced diabetic male albino rats have shown that compounds 4e and 4f significantly reduced blood glucose levels with percentage reduction of 43.7 ± 0.91 and 45.6 ± 0.28 at a concentration of 50 mg/kg body wt. The results obtained from molecular docking simulations and in vitro enzyme assays are in consistent with in-vivo studies which clearly demonstrated that out of the synthesized quinoline analogues, compounds 4e and 4f possess promising hypoglycemic activity which was on par to that of standards pioglitazone and rosiglitazone respectively.

A survey of substrate specificity among Auxiliary Activity Family 5 copper radical oxidases

There is significant contemporary interest in the application of enzymes to replace or augment chemical reagents toward the development of more environmentally sound and sustainable processes. In particular, copper radical oxidases (CRO) from Auxiliary Activity Family 5 Subfamily 2 (AA5_2) are attractive, organic cofactor-free catalysts for the chemoselective oxidation of alcohols to the corresponding aldehydes. These enzymes were first defined by the archetypal galactose-6-oxidase (GalOx, EC 1.1.3.13) from the fungus Fusarium graminearum. The recent discovery of specific alcohol oxidases (EC 1.1.3.7) and aryl alcohol oxidases (EC 1.1.3.47) within AA5_2 has indicated a potentially broad substrate scope among fungal CROs. However, only relatively few AA5_2 members have been characterized to date. Guided by sequence similarity network and phylogenetic analysis, twelve AA5_2 homologs have been recombinantly produced and biochemically characterized in the present study. As defined by their predominant activities, these comprise four galactose 6-oxidases, two raffinose oxidases, four broad-specificity primary alcohol oxidases, and two non-carbohydrate alcohol oxidases. Of particular relevance to applications in biomass valorization, detailed product analysis revealed that two CROs produce the bioplastics monomer furan-2,5-dicarboxylic acid (FDCA) directly from 5-hydroxymethylfurfural (HMF). Furthermore, several CROs could desymmetrize glycerol (a by-product of the biodiesel industry) to D- or L-glyceraldehyde. This study furthers our understanding of CROs by doubling the number of characterized AA5_2 members, which may find future applications as biocatalysts in diverse processes.

Enzyme-support interactions and inactivation conditions determine Thermomyces lanuginosus lipase inactivation pathways: Functional and florescence studies

Lipase from Thermomyces lanuginosus (TLL) has been covalently immobilized on heterofunctional octyl-vinyl agarose. That way, the covalently immobilized enzymes will have identical orientation. Then, it has blocked using hexyl amine (HEX), ethylenediamine (EDA), Gly and Asp. The initial activity/stability of the different biocatalysts was very different, being the most stable the biocatalyst blocked with Gly. These biocatalysts had been utilized to analyze if the enzyme activity could decrease differently along thermal inactivation courses depending on the utilized substrate (that is, if the enzyme specificity was altered during its inactivation using 4 different substrates to determine the activity), and if this can be altered by the nature of the blocking agent and the inactivation conditions (we use pH 5, 7 and 9). Results show great changes in the enzyme specificity during inactivation (e.g., activity versus triacetin was much more quickly lost than versus the other substrates), and how this was modulated by the immobilization protocol and inactivation conditions. The difference in the changes induced by immobilization and inactivation were confirmed by fluorescence studies. That is, the functional and structural analysis of partially inactivated immobilized enzyme showed that their inactivation pathway is strongly depended on the support features and inactivation conditions.