Designing multifunctional biocatalytic cascade system by multi-enzyme co-immobilization on biopolymers and nanostructured materials

Engineering a Bifunctional Fusion Purine/Pyrimidine Nucleoside Phosphorylase for the Production of Nucleoside Analogs

Nucleoside phosphorylases (NPs) are pivotal enzymes in the salvage pathway, catalyzing the reversible phosphorolysis of nucleosides to produce nucleobases and α-D-ribose 1-phosphate. Due to their efficiency in catalyzing nucleoside synthesis from purine or pyrimidine bases, these enzymes hold significant industrial importance in the production of nucleoside-based drugs. Given that the thermodynamic equilibrium for purine NPs (PNPs) is favorable for nucleoside synthesis-unlike pyrimidine NPs (PyNPs, UP, and TP)-multi-enzymatic systems combining PNPs with PyNPs, UPs, or TPs are commonly employed in the synthesis of nucleoside analogs. In this study, we report the first development of two engineered bifunctional fusion enzymes, created through the genetic fusion of purine nucleoside phosphorylase I (PNP I) and thymidine phosphorylase (TP) from Thermus thermophilus. These fusion constructs, PNP I/TP-His and TP/PNP I-His, provide an innovative one-pot, single-step alternative to traditional multi-enzymatic synthesis approaches. Interestingly, both fusion enzymes retain phosphorolytic activity for both purine and pyrimidine nucleosides, demonstrating significant activity at elevated temperatures (60-90 °C) and within a pH range of 6-8. Additionally, both enzymes exhibit high thermal stability, maintaining approximately 80-100% of their activity when incubated at 60-80 °C over extended periods. Furthermore, the transglycosylation capabilities of the fusion enzymes were explored, demonstrating successful catalysis between purine (2'-deoxy)ribonucleosides and pyrimidine bases, and vice versa. To optimize reaction conditions, the effects of pH and temperature on transglycosylation activity were systematically examined. Finally, as a proof of concept, these fusion enzymes were successfully employed in the synthesis of various purine and pyrimidine ribonucleoside and 2'-deoxyribonucleoside analogs, underscoring their potential as versatile biocatalysts in nucleoside-based drug synthesis.

Single-cell enzymatic cascade synthesis of testolactone enabled by engineering of polycyclic ketone monooxygenase and multi-gene expression fine-tuning

The synthesis of steroids is challenging through multistep steroidal core modifications with high site-selectivity and productivity. In this work, a novel enzymatic cascade system was constructed for synthesis of testolactone by specific C17 lactonization/Δ1-dehydrogenation from inexpensive androstenedione using an engineered polycyclic ketone monooxygenase (PockeMO) and an appropriate 3-ketosteroid-Δ1-dehydrogenase (ReKstD). The focused saturation mutagenesis in the substrate binding pocket was implemented for evolution of PockeMO to eliminate the bottleneck effect. A best mutant MU3 (I225L/L226V/L532Y) was obtained with 20-fold higher specific activity compared to PockeMO. The catalytic efficiency (kcat/Km) of MU3 was 171-fold higher and the substrate scope shifted to polycyclic ketones. Molecular dynamic simulations suggested that the activity was improved by stabilization of the pre-lactonization state and generation of productive orientation of 4-AD mediated by distal L532Y mutation. Based on that, the three genes, MU3, ReKstD and a ketoreductase for NADPH regeneration, were rationally integrated in one cell via expression fine-tuning to form the efficient single cell catalyst E. coli S9. The single whole-cell biocatalytic process was scaled up and could generate 9.0 g/L testolactone with the high space time yield of 1 g/L/h without steroidal by-product, indicating the potential for site-specific and one-pot synthesis of steroid.

Precision Engineering of the Co-immobilization of Enzymes for Cascade Biocatalysis

The design and orderly layered co-immobilization of multiple enzymes on resin particles remain challenging. In this study, the SpyTag/SpyCatcher binding pair was fused to the N-terminus of an alcohol dehydrogenase (ADH) and an aldo-keto reductase (AKR), respectively. A non-canonical amino acid (ncAA), p-azido-L-phenylalanine (p-AzF), as the anchor for covalent bonding enzymes, was genetically inserted into preselected sites in the AKR and ADH. Employing the two bioorthogonal counterparts of SpyTag/SpyCatcher and azide-alkyne cycloaddition for the immobilization of AKR and ADH enabled sequential dual-enzyme coating on porous microspheres. The ordered dual-enzyme reactor was subsequently used to synthesize (S)-1-(2-chlorophenyl)ethanol asymmetrically from the corresponding prochiral ketone, enabling the in situ regeneration of NADPH. The reactor exhibited a high catalytic conversion of 74 % and good reproducibility, retaining 80 % of its initial activity after six cycles. The product had 99.9 % ee, which that was maintained in each cycle. Additionally, the double-layer immobilization method significantly increased the enzyme loading capacity, which was approximately 1.7 times greater than that of traditional single-layer immobilization. More importantly, it simultaneously enabled both the purification and immobilization of multiple enzymes on carriers, thus providing a convenient approach to facilitate cascade biocatalysis.

Biomimetic immobilization of α-glucosidase inspired by antibody-antigen specific recognition for catalytic preparation of 4-methylumbelliferone

Immobilization technology plays an important role in enhancing enzyme stability and environmental adaptability. Despite its rapid development, this technology still encounters many challenges such as enzyme leakage, difficulties in large-scale implementation, and limited reusability. Drawing inspiration from natural paired molecules, this study aimed to establish a method for immobilized α-glucosidase using artificial antibody-antigen interaction. The proposed method consists of three main parts: synthesis of artificial antibodies, synthesis of artificial antigens, and assembly of the artificial antibody-antigen complex. The critical step in this method involves selecting a pair of structurally similar compounds: catechol as a template for preparing artificial antibodies and protocatechualdehyde for modifying the enzyme to create the artificial antigens. By utilizing the same functional groups in these compounds, specific recognition of the antigen by the artificial antibody can be achieved, thereby immobilizing the enzymes. The results demonstrated that the immobilization amount, specific activity, and enzyme activity of the immobilized α-glucosidase were 25.09 ± 0.10 mg/g, 5.71 ± 0.17 U/mgprotein and 143.25 ± 1.71 U/gcarrier, respectively. The immobilized α-glucosidase not only exhibited excellent reusability but also demonstrated remarkable performance in catalyzing the hydrolysis of 4-methylumbelliferyl-α-D-glucopyranoside.

Catalytic Synthesis of (S)-CHBE by Directional Coupling and Immobilization of Carbonyl Reductase and Glucose Dehydrogenase

Ethyl (S)-4-chloro-3-hydroxybutyrate ((S)-CHBE) is an important chiral intermediate in the synthesis of the cholesterol-lowering drug atorvastatin. Studying the use of SpyTag/SpyCatcher and SnoopTag/SnoopCatcher systems for the asymmetric reduction reaction and directed coupling coenzyme regeneration is practical for efficiently synthesizing (S)-CHBE. In this study, Spy and Snoop systems were used to construct a double-enzyme directed fixation system of carbonyl reductase (BsCR) and glucose dehydrogenase (BsGDH) for converting 4-chloroacetoacetate (COBE) to (S)-CHBE and achieving coenzyme regeneration. We discussed the enzymatic properties of the immobilized enzyme and the optimal catalytic conditions and reusability of the double-enzyme immobilization system. Compared to the free enzyme, the immobilized enzyme showed an improved optimal pH and temperature, maintaining higher relative activity across a wider range. The double-enzyme immobilization system was applied to catalyze the asymmetric reduction reaction of COBE, and the yield of (S)-CHBE reached 60.1% at 30 °C and pH 8.0. In addition, the double-enzyme immobilization system possessed better operational stability than the free enzyme, and maintained about 50% of the initial yield after six cycles. In summary, we show a simple and effective strategy for self-assembling SpyCatcher/SnoopCatcher and SpyTag/SnoopTag fusion proteins, which inspires building more cascade systems at the interface. It provides a new method for facilitating the rapid construction of in vitro immobilized multi-enzyme complexes from crude cell lysate.

Enhancing biocatalyst performance through immobilization of lipase (Eversa® Transform 2.0) on hybrid amine-epoxy core-shell magnetic nanoparticles

Magnetic nanoparticles were functionalized with polyethylenimine (PEI) and activated with epoxy. This support was used to immobilize Lipase (Eversa® Transform 2.0) (EVS), optimization using the Taguchi method. XRF, SEM, TEM, XRD, FTIR, TGA, and VSM performed the characterizations. The optimal conditions were immobilization yield (I.Y.) of 95.04 ± 0.79 %, time of 15 h, ionic load of 95 mM, protein load of 5 mg/g, and temperature of 25 °C. The maximum loading capacity was 25 mg/g, and its stability in 60 days of storage showed a negligible loss of only 9.53 % of its activity. The biocatalyst demonstrated better stability at varying temperatures than free EVS, maintaining 28 % of its activity at 70 °C. It was feasible to esterify free fatty acids (FFA) from babassu oil with the best reaction of 97.91 % and ten cycles having an efficiency above 50 %. The esterification of produced biolubricant was confirmed by NMR, and it displayed kinematic viscosity and density of 6.052 mm2/s and 0.832 g/cm3, respectively, at 40 °C. The in-silico study showed a binding affinity of -5.8 kcal/mol between EVS and oleic acid, suggesting a stable substrate-lipase combination suitable for esterification.

Combined cross-linking of Rhizomucor miehei lipase and Candida antarctica lipase B for the effective enrichment of omega-3 fatty acids in fish oil

The incorporation of a non-specific lipase and a sn-1,3 specific one in a single immobilized system can be a promising approach for the exploitation of both lipases. A one-step immobilization platform mediated by an isocyanide-based multi-component reaction was applied to create co-cross-linked enzymes (co-CLEs) of lipases from Rhizomucor miehei (sn-1,3 specific) and Candida antarctica (non-specific). Glutaraldehyde was found to be effective cross-linker by producing specific activity of 16.9 U/mg and immobilization yield of 99 %. High activity recovery of up to 404 % was obtained for immobilized derivatives. Leaking experiment showed covalent nature of the cross-linking processes. BSA had considerable effect on the immobilization process, providing 87-100 % immobilization yields and up to 10 times improvement in the specific activity of the immobilized derivatives. Scanning electron microscopy images showed flower-like and rod-like structures for the CLEs prepared by glutaraldehyde and undecanedicarboxylic acid, respectively. The prepared co-CLEs were examined in non-selective enrichment of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish oil, showing capability of releasing up to 100 % of both omega-3 fatty acids within 8 h of the reaction. The reusability of co-CLEs in five successive cycles presented retaining 63-72 % of their initial activities after the fifth reuse cycle in the hydrolysis reaction.

Algal carbohydrate polymers: Catalytic innovations for sustainable development

Algal polysaccharides, harnessed for their catalytic potential, embody a compelling narrative in sustainable chemistry. This review explores the complex domains of algal carbohydrate-based catalysis, revealing its diverse trajectory. Starting with algal polysaccharide synthesis and characterization methods as catalysts, the investigation includes sophisticated techniques like NMR spectroscopy that provide deep insights into the structural variety of these materials. Algal polysaccharides undergo various preparation and modification techniques to enhance their catalytic activity such as immobilization. Homogeneous catalysis, revealing its significance in practical applications like crafting organic compounds and facilitating chemical transformations. Recent studies showcase how algal-derived catalysts prove to be remarkably versatile, showcasing their ability to customise reactions for specific substances. Heterogeneous catalysis, it highlights the significance of immobilization techniques, playing a central role in ensuring stability and the ability to reuse catalysts. The practical applications of heterogeneous algal catalysts in converting biomass and breaking down contaminants, supported by real-life case studies, emphasize their effectiveness. In sustainable chemistry, algal polysaccharides emerge as compelling catalysts, offering a unique intersection of eco-friendliness, structural diversity, and versatile catalytic properties. Tackling challenges such as dealing with complex structural variations, ensuring the stability of the catalyst, and addressing economic considerations calls for out-of-the-box and inventive solutions. Embracing the circular economy mindset not only assures sustainable catalyst design but also promotes efficient recycling practices. The use of algal carbohydrates in catalysis stands out as a source of optimism, paving the way for a future where chemistry aligns seamlessly with nature, guiding us toward a sustainable, eco-friendly, and thriving tomorrow. This review encapsulates-structural insights, catalytic applications, challenges, and future perspectives-invoking a call for collective commitment to catalyze a sustainable scientific revolution.

Recent applications and future prospects of magnetic biocatalysts

Magnetic biocatalysts combine magnetic properties with the catalytic activity of enzymes, achieving easy recovery and reuse in biotechnological processes. Lipases immobilized by magnetic nanoparticles dominate. This review covers an advanced bibliometric analysis and an overview of the area, elucidating research advances. Using WoS, 34,949 publications were analyzed and refined to 450. The prominent journals, countries, institutions, and authors that published the most were identified. The most cited articles showed research hotspots. The analysis of the themes and keywords identified five clusters and showed that the main field of research is associated with obtaining biofuels derived from different types of sustainable vegetable oils. The overview of magnetic biocatalysts showed that these materials are also employed in biosensors, photothermal therapy, environmental remediation, and medical applications. The industry shows a significant interest, with the number of patents increasing. Future studies should focus on immobilizing new lipases in unique materials with magnetic profiles, aiming to improve the efficiency for various biotechnological applications.

Cellulase immobilization to enhance enzymatic hydrolysis of lignocellulosic biomass: An all-inclusive review

Cellulase-mediated lignocellulosic biorefinery plays a crucial role in the production of high-value biofuels and chemicals, with enzymatic hydrolysis being an essential component. The advent of cellulase immobilization has revolutionized this process, significantly enhancing the efficiency, stability, and reusability of cellulase enzymes. This review offers a thorough analysis of the fundamental principles underlying immobilization, encompassing various immobilization approaches such as physical adsorption, covalent binding, entrapment, and cross-linking. Furthermore, it explores a diverse range of carrier materials, including inorganic, organic, and hybrid/composite materials. The review also focuses on emerging approaches like multi-enzyme co-immobilization, oriented immobilization, immobilized enzyme microreactors, and enzyme engineering for immobilization. Additionally, it delves into novel carrier technologies like 3D printing carriers, stimuli-responsive carriers, artificial cellulosomes, and biomimetic carriers. Moreover, the review addresses recent obstacles in cellulase immobilization, including molecular-level immobilization mechanism, diffusion limitations, loss of cellulase activity, cellulase leaching, and considerations of cost-effectiveness and scalability. The knowledge derived from this review is anticipated to catalyze the evolution of more efficient and sustainable biocatalytic systems for lignocellulosic biomass conversion, representing the current state-of-the-art in cellulase immobilization techniques.

(Magnetic) Cross-Linked Enzyme Aggregates of Cellulase from T. reesei: A Stable and Efficient Biocatalyst

Cross-linked enzyme aggregates (CLEAs) represent an effective tool for carrier-free immobilization of enzymes. The present study promotes a successful application of functionalized magnetic nanoparticles (MNPs) for stabilization of cellulase CLEAs. Catalytically active CLEAs and magnetic cross-linked enzyme aggregates (mCLEAs) of cellulase from Trichoderma reesei were prepared using glutaraldehyde (GA) as a cross-linking agent and the catalytic activity and stability of the CLEAs/mCLEAs were investigated. The influence of precipitation agents, cross-linker concentration, concentration of enzyme, addition of bovine serum albumin (BSA), and addition of sodium cyanoborohydride (NaBH₃CN) on expressed activity and immobilization yield of CLEAs/mCLEAs was studied. Particularly, reducing the unsaturated Schiff's base to form irreversible linkages is important and improved the activity of CLEAs (86%) and mCLEAs (91%). For increased applicability of CLEAs/mCLEAs, we enhanced the activity and stability at mild biochemical process conditions. The reusability after 10 cycles of both CLEAs and mCLEAs was investigated, which retained 72% and 65% of the initial activity, respectively. The thermal stability of CLEAs and mCLEAs in comparison with the non-immobilized enzyme was obtained at 30 °C (145.65% and 188.7%, respectively) and 50 °C (185.1% and 141.4%, respectively). Kinetic parameters were determined for CLEAs and mCLEAs, and the K_M constant was found at 0.055 ± 0.0102 mM and 0.037 ± 0.0012 mM, respectively. The maximum velocity rate (V_max) was calculated as 1.12 ± 0.0012 µmol/min for CLEA and 1.17 ± 0.0023 µmol/min for mCLEA. Structural characterization was studied using XRD, SEM, and FT-IR. Catalytical properties of immobilized enzyme were improved with the addition of reducent NaBH₃CN by enhancing the activity of CLEAs and with addition of functionalized aminosilane MNPs by enhancing the activity of mCLEAs.