Recent trends in biocatalysis

Multifunctional nanozymatic biosensors: Awareness, regulation and pathogenic bacteria detection

It is estimated that approximately 700,000 fatalities occur annually due to infections attributed to various pathogens, which are capable of dissemination via multiple environmental vectors, including air, water, and soil. Consequently, there is an urgent need to enhance and refine rapid detection technologies for pathogens to prevent and control the spread of associated diseases. This review focuses on applying nanozymes in constructing biosensors, particularly their advancement in detecting pathogenic bacteria. Nanozymes, which are nanomaterials exhibiting enzyme-like activity, combine unique magnetic, optical, and electronic properties with structural diversity. This blend of characteristics makes them highly appealing for use in biocatalytic applications. Moreover, their nanoscale dimensions facilitate effective contact with pathogenic bacteria, leading to efficient detection and antibacterial effects. This article briefly summarizes the development, classification, and strategies for regulating the catalytic activity of nanozymes. It primarily focuses on recent advancements in constructing biosensors that utilize nanozymes as probes for sensitively detecting pathogenic bacteria. The discussion covers the development of various optical and electrochemical biosensors, including colorimetric, fluorescence, surface-enhanced Raman scattering (SERS), and electrochemical methods. These approaches provide a reliable solution for the sensitive detection of pathogenic bacteria. Finally, the challenges and future development directions of nanozymes in pathogen detection are discussed.

Fusion of enzymatic proteins: Enhancing biological activities and facilitating biological modifications

The fusion of enzymatic proteins represents a dynamic frontier in biotechnology and enzymatic engineering. This in-depth review looks at the many different ways that fusion proteins can be used, showing their importance in biosensing, gene therapy, targeted drug delivery, and biocatalysis. Fusion proteins have shown an astounding ability to improve and fine-tune biological functions by combining the most beneficial parts of different enzymes. Our first step is to explain how protein fusion increases biological functions. This will provide a broad picture of how this phenomenon has changed many fields. We dissect the intricate mechanisms through which fusion proteins orchestrate cellular processes, underscoring their potential to revolutionize the landscape of molecular biology. We also explore the complicated world of structural analysis and design strategies, stressing the importance of molecular insights for making the fusion protein approach work better. These insights broaden understanding of the underlying principles and illuminate the path toward unlocking untapped potential. The review also introduces cutting-edge techniques for constructing fusion protein libraries, such as DNA shuffling and phage display. These new methods allow scientists to build a molecular orchestra with an unprecedented level of accuracy, and thus use fusion proteins to their full potential in various situations. In conclusion, we provide a glimpse into the current challenges and prospects in fusion protein research, shedding light on recent advancements that promise to reshape the future of biotechnology. As we make this interesting journey through the field of enzymatic protein combination, it becomes clear that the fusion paradigm is about to start a new era of innovation that will push the limits of what is possible in biology and molecular engineering.

Light-Driven Deracemization by a Designed Photoenzyme

The creation of enzymes with abiological abilities offers exciting opportunities to access new-to-nature biocatalysis beyond that found in nature. Here, we repurpose a novel protein scaffold, CTB10, as an artificial photoenzyme through genetic code expansion. It enables catalytic deracemization of cyclopropane, a process that remains inaccessible to traditional biocatalysis due to its thermodynamically unfavorable nature. Following structural optimization through directed evolution, a broad substrate scope with high enantioselectivities is achieved. Furthermore, the crystal structure of the CTB10-based photoenzyme-substrate complex well demonstrates how the catalytic chiral cavity is sculpted to promote efficient and selective light-enabled deracemization. Therefore, this study unlocks the potential for achieving challenging deracemization through biocatalysis.

Biocatalytic Synthesis of Corticosteroid Derivatives by Toad-Derived Steroid C21-Hydroxylase

CsCYP21A, a steroid 21-hydroxylase from Bufo bufo gargarizans, exhibits unprecedented sequential oxidations. Optimizing Pichia pastoris biotransformation conditions enhanced C21-hydroxylation selectivity, converting 14 substrates to 21-hydroxylated products, with 10 conversions of >80% and 4 yields of >80%. Hydrocortisone production reached 1.5 g L-1 day-1 with 100 g/L wet biomass. CsCYP21A's versatility enables integration into the synthesis of over 10 steroidal drugs, offering a sustainable biocatalytic platform for green pharmaceutical manufacturing.

Recent advances in biological synthesis of food additive succinate

Succinate, a crucial bio-based chemical building block, has already found extensive applications in fields such as food additives, pharmaceutical intermediates, and the chemical materials industry. To efficiently and economically synthesize succinate, substantial endeavors have been executed to optimize fermentation processes and downstream operations. Nonetheless, there is still a need to enhance cost-effectiveness and competitiveness while considering environmental concerns, particularly in light of the escalating demands and challenges posed by global warming. This article primarily focuses on the application of metabolic engineering strategies to strengthen succinate biosynthesis. These strategies encompass fermentation regulation, metabolic regulation, cellular regulation, and model guidance. By leveraging advanced synthetic biology techniques, this review highlights the potential for developing robust microbial cell factories and shaping the future directions for the integration of microbes in industrial applications.

Navigating Side Reactions for Robust Colorimetric Detection of Galactose Oxidase Activity

Colorimetric assays are a rapid, scalable technique well suited to enzyme activity screening. However, side reactions or chromogenic reagent instability can result in false positives or false negatives that compromise the accuracy of such assays. Here, we identify three classes of compounds incompatible with the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) colorimetric assay for galactose oxidase activity. Dark green ABTS·+ cationic radicals indicating enzyme activity can get quenched to yield colorless solutions or couple with substrates to form differently colored adducts, thus preventing accurate colorimetric measurements. These side reactions limit the utility of the ABTS assay and introduce uncertainty in the substrate scope to which it is applicable. We have investigated the underlying mechanisms behind these side reactions to conclude that free radical scavengers, phenols with electron-donating substituents, and β,γ-unsaturated aryl ketones are incompatible with the ABTS colorimetric assay. In search of a viable alternative, we developed an assay using 2,4-dinitrophenylhydrazine under neutral conditions with isopropyl alcohol as a solubilizing agent. The use of neutral conditions was found to be critical to avoid hydrolysis of hydrazone adducts, ensuring reproducible measurements. Our assay is compatible with free radical scavengers (R2 = 0.98), phenols with electron-donating substituents (R2 = 0.97), and β,γ-unsaturated aryl ketones (R2 = 0.88). This modified assay enables galactose oxidase activity screening across a broader substrate scope, thus facilitating enzyme use for more practical applications.

De Novo Synthesis of Reticuline and Taxifolin Using Re-engineered Homologous Recombination in Yarrowia lipolytica

Yarrowia lipolytica has been widely engineered as a eukaryotic cell factory to produce various important compounds. However, the difficulty of gene editing and the lack of efficient neutral sites make rewiring of Y. lipolytica metabolism challenging. Herein, a Cas9 system was established to redesign the Y. lipolytica homologous recombination system, which caused a more than 56-fold increase in the HR efficiency. The fusion expression of the hBrex27 sequence in the C-terminus of Cas9 recruited more Rad51 protein, and the engineered Cas9 decreased NHEJ, achieving 85% single-gene positive efficiency and 25% multigene editing efficiency. With this system, neutral sites on different chromosomes were characterized, and a deep learning model was developed for gRNA activity prediction, thus providing the corresponding integration efficiency and expression intensity. Subsequently, the tool and platform strains were validated by applying them for the de novo synthesis of (S)-reticuline and (2S)-taxifolin. The developed platform strains and tools helped transform Y. lipolytica into an easy-to-operate model cell factory, similar to Saccharomyces cerevisiae.

Advances and prospects on production of lactulose and epilactose by cellobiose 2-epimerases: A review

Lactulose and epilactose are nondigestible disaccharides with a wide range of applications in clinical medicine, nutrition, and the food industry due to their health-benefiting properties. Their chemical synthesis typically involves stringent catalytic conditions and intricate reaction procedures, resulting in elevated production costs and challenges in product separation. Cellobiose 2-epimerases (CEs) facilitate the isomerization and epimerization of lactose to produce lactulose and epilactose directly, without the need for co-substrates. This enzymatic process offers advantages such as mild reaction conditions, straightforward operation, high conversion efficiency, and reduced by-product formation. Recently, numerous CE genes have been identified and characterized, with their enzymatic properties undergoing extensive analysis. This review consolidates information on the properties of CEs from various sources and examines their catalytic mechanisms based on crystal structure data. Additionally, the current research progress in the enzymatic synthesis of lactulose and epilactose is comprehensively reviewed. The future direction of CE research is discussed, highlighting the potential for large-scale production of lactulose and epilactose through environmentally sustainable enzymatic methods.

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

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

Tailored Metal-Organic Framework-Based Nanozymes for Enhanced Enzyme-Like Catalysis

The global crisis of bacterial infections is exacerbated by the escalating threat of microbial antibiotic resistance. Nanozymes promise to provide ingenious solutions. Here, we reported a homogeneous catalytic structure of Pt nanoclusters with finely tuned metal-organic framework (ZIF-8) channel structures for the treatment of infected wounds. Catalytic site normalization showed that the active site of the Pt aggregates structure with fine-tuned pore modifications structure had a catalytic capacity of 14.903×105 min-1, which was 18.7 times higher than that of the Pt particles in monodisperse state in ZIF-8 (0.793×105 min-1). In situ tests revealed that the change from homocleavage to heterocleavage of hydrogen peroxide at the interface of the nanozyme was one of the key reasons for the improvement of nanozyme activity. Density-functional theory and kinetic simulations of the reaction interface jointly determine the role of the catalytic center and the substrate channel together. Metabolomics analysis showed that the developed nanozyme, working in conjunction with reactive oxygen species, could effectively block energy metabolic pathways within bacteria, leading to spontaneous apoptosis and bacterial rupture. This pioneering study elucidates new ideas for the regulation of artificial enzyme activity and provides new perspectives for the development of efficient antibiotic substitutes.

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

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

LDHzyme-assisted high-performance on-site tracking of levodopa pharmacokinetics for Parkinson's disease management

Parkinson's disease (PD) is a progressive neurodegenerative disorder marked by the loss of dopaminergic neurons and the consequent decline in motor and cognitive functions. The primary therapeutic agent levodopa necessitates precise dosing due to its narrow therapeutic window and complex pharmacokinetics. This study presents the development of a novel CuCoFe-LDHzyme-based sweat sensor for real-time monitoring of levodopa concentration in PD patients. Employing differential pulse voltammetry (DPV) technique, the sensor demonstrates high sensitivity and selectivity, achieving a detection limit of 28.1 nM. The sensor's design allows for non-invasive, continuous monitoring, significantly enhancing patient convenience compared to traditional blood sampling methods. Through pH correction, precise quantification of levodopa in sweat is accomplished, and a strong correlation (Pearson coefficient = 0.833) with blood levodopa levels is established. The pharmacokinetic profile of levodopa is reconstructed in real-time, offering a promising tool for optimizing PD treatment regimens. This study highlights the potential of CuCoFe-LDHzyme sensors to advance personalized treatment strategies, aiming to improve the quality of life for PD patients by providing clinicians with real-time data for medication adjustments.

Biosensor-Guided Engineering of a Baeyer-Villiger Monooxygenase for Aliphatic Ester Production

Esters are valuable aroma compounds and can be produced enzymatically by Baeyer-Villiger monooxygenases (BVMOs) from (aliphatic) ketone precursors. However, a genetically encoded biosensor system for the assessment of BVMO activity and the detection of reaction products is missing. In this work, we assembled a synthetic enzyme cascade - featuring an esterase, an alcohol dehydrogenase, and LuxAB - in the heterologous host Escherichia coli. Target esters are produced by a BVMO, subsequently cleaved, and the corresponding alcohol oxidized through the artificial pathway. Ultimately, aldehyde products are detected in vivo by LuxAB, a luciferase from Photorhabdus luminescens that emits bioluminescence upon the oxidation of aldehydes to the corresponding carboxylates. This biosensor system greatly accelerated the screening and selection of active BVMO variants from a focused library, omitting commonly used low-throughput chromatographic analysis. Engineered enzymes accepted linear aliphatic ketones such as 2-undecanone and 2-dodecanone and exhibited improved ester formation.

Chemoenzymatic Synthesis Planning Guided by Reaction Type Score

Thanks to the growing interest in computer-aided synthesis planning (CASP), a wide variety of retrosynthesis and retrobiosynthesis tools have been developed in the past decades. However, synthesis planning tools for multistep chemoenzymatic reactions are still rare despite the widespread use of enzymatic reactions in chemical synthesis. Herein, we report a reaction type score (RTscore)-guided chemoenzymatic synthesis planning (RTS-CESP) strategy. Briefly, the RTscore is trained using a text-based convolutional neural network (TextCNN) to distinguish synthesis reactions from decomposition reactions and evaluate synthesis efficiency. Once multiple chemical synthesis routes are generated by a retrosynthesis tool for a target molecule, RTscore is used to rank them and find the step(s) that can be replaced by enzymatic reactions to improve synthesis efficiency. As proof of concept, RTS-CESP was applied to 10 molecules with known chemoenzymatic synthesis routes in the literature and was able to predict all of them with six being the top-ranked routes. Moreover, RTS-CESP was employed for 1000 molecules in the boutique database and was able to predict the chemoenzymatic synthesis routes for 554 molecules, outperforming ASKCOS, a state-of-the-art chemoenzymatic synthesis planning tool. Finally, RTS-CESP was used to design a new chemoenzymatic synthesis route for the FDA-approved drug Alclofenac, which was shorter than the literature-reported route and has been experimentally validated.

Ancestral Sequence Reconstruction for Designing Biocatalysts and Investigating their Functional Mechanisms

Biocatalysis has emerged as a green approach for efficient and sustainable production in various industries. In recent decades, numerous advancements in computational and predictive approaches, including ancestral sequence reconstruction (ASR) have sparked a new wave for protein engineers to improve and expand biocatalyst capabilities. ASR is an evolution-based strategy that uses phylogenetic relationships among homologous extant sequences to probabilistically infer the most likely ancestral sequences. It has proven to be a powerful tool with applications ranging from creating highly stable enzymes for direct applications to preparing moderately active robust protein scaffolds for further enzyme engineering. Intriguingly, it can also provide insights into fundamental aspects that are challenging to study with extant (current) enzymes. This Perspective discusses a practical strategy for guiding enzyme engineers on how to embrace ASR as a practical or associated protocol for protein engineering and highlights recent examples of using ASR in various applications, including increasing thermostability, expanding promiscuity, fine-tuning selectivity and function, and investigating mechanistic and evolution aspects. We believe that the use of the ASR approach will continue to contribute to the ongoing development of the biocatalysis field. We have been in a "golden era" for biocatalysis in which numerous useful enzymes have been developed through many waves of enzyme engineering via advancements in computational methodologies.

Genetically encoded biosensors for the circular plastics bioeconomy

Current plastic production and consumption routes are unsustainable due to impact upon climate change and pollution, and therefore reform across the entire value chain is required. Biotechnology offers solutions for production from renewable feedstocks, and to aid end of life recycling/upcycling of plastics. Biology sequence/design space is complex requiring high-throughput analytical methods to facilitate the iterative optimisation, design-build, test-learn (DBTL), cycle of Synthetic Biology. Furthermore, genetic regulatory tools can enable harmonisation between biotechnological demands and the physiological constraints of the selected production host. Genetically encoded biosensors offer a solution for both requirements to facilitate the circular plastic bioeconomy. In this review we present a summary of biosensors developed to date reported to be responsive to plastic precursors/monomers. In addition, we provide a summary of the demonstrated and prospective applications of these biosensors for the construction and deconstruction of plastics. Collectively, this review provides a valuable resource of biosensor tools and enabled applications to support the development of the circular plastics bioeconomy.

Structural and functional optimization of glycoprotein-enzymes for targeted biocatalysis in oral squamous cell carcinoma

The efficacy of optimized glycoproteinenzymes as a novel therapeutic approach for oral squamous cell carcinoma (OSCC) was tested in this study. The stability and viability of SCC-25 and HN4 operating-system cell lines were characterized. Both lines were confirmed to have a spindle-like morphology for SCC-25, while HN4 cells exhibited cobblestone-like clusters. Viability decreased with time for cell clones SCC-25 was 95 % and 80 % after five days, while HN4 was 94 % and 79 %. Enzyme 1, expression in E. coli and Pichia pastoris to high purity recombinant glycoprotein-enzymes. Activities of these enzymes varied equally among experimental conditions. The enzyme showed an activity of 18 units at Condition D as active max, Enzyme 2 retraced 16 units, and Enzyme 3 reached this point in the same condition. Differences in activity between different conditions were also found in various experimental conditions. In therapeutic assessments, glycoprotein-enzyme treatment lowered OSCC cell viability with IC50 values of 10-15 g/ml. Successful cellular localization could be detected primarily in the cytoplasm and nucleus of live animal tissue following treatment with those therapies. In preclinical xenograft models, treatment resulted in a 40-50 % reduction in tumour volume and growth rates, with treated tumours displaying a 60 % decrease in Ki-67, a 50 % reduction in Bcl-2, and a 70 % increase in cleaved caspase-3. Additionally, the Bax/Bcl-2 ratio increased by 80 %, and CD31 staining revealed a 40 % reduction in microvessel density. These results suggest that optimized glycoprotein enzyme therapy effectively inhibits tumour growth, induces apoptosis and reduces angiogenesis, thus laying a solid foundation for its application in clinical therapy of OSCC.

Mining and Engineering the Di-O-glycosylation Pattern of UGT72B1 for the Highly Efficient O-Glycosylation of Endogenous Quercetin

Compared with mono-O-glycosylation, di-O-glycosylation endows the precursor with better performance. However, the mining and engineering of di-O-glycosylation patterns of glycosyltransferases are limited, hindering their synthetic applications. Here, an Arabidopsis xenobiotic-transforming glycosyltransferase, UGT72B1, was found to catalyze the glycosylation of endogenous quercetin and its monoglycosides, generating di-O-glucosides. Mutating M17/G18/Y315 into L/T/Q in UGT72B1 altered its regioselectivity toward quercetin 7-O-glucoside, enzymatically generating another 3,7-di-O-glycoside with up to a 100% conversion rate, and increased the sugar donor preference. Altering the regiospecificity of glycosyltransferases likely required coordination between the entrance and the active site, where the orientations of the sugar acceptors and donors shift to adopt a lower binding energy state. Moreover, quercetin 3,4'-di-O-β-d-glucoside and quercetin 3,7-di-O-β-d-glucoside synthesized were found to have the highest anti-inflammatory activities. Overall, this work presents an efficient strategy to engineer glycosylation patterns for the synthesis of quercetin di-O-β-d-glucosides to be used as food additives, therapeutics, and nutraceuticals.

A Single Enzyme in Enantiocomplementary Synthesis of β-Nitroalcohols: Bidirectional Catalysis by Hydroxynitrile Lyase

A single enzyme, Baliospermum montanum hydroxynitrile lyase (BmHNL), without alteration, enabled bidirectional catalysis in enantiocomplementary synthesis of chiral β-nitroalcohols. BmHNL catalyzed promiscuous Henry (24 examples) and retro-Henry reaction (22 examples) provided up to >99 % and 50 % conversion to (S)- and (R)-β-nitroalcohols respectively, while both cases displayed up to >99 % ee. The broad substrate scope and high stereoselectivity of BmHNL represents its synthetic applications in sustainable production of diverse chiral β-nitroalcohols. Kinetic parameters of BmHNL was determined for Henry and retro-Henry reaction, which reveals poor catalytic efficiency for both the promiscuous transformations, however, the former has better efficiency than the latter. Practical applicability of the biocatalyst and transformation was illustrated by preparative scale synthesis of chiral intermediates of (S)-Tembamide, and (S)-Micanozole.

Yeast surface display technology: Mechanisms, applications, and perspectives

Microbial cell surface display technology, which relies on genetically fusing heterologous target proteins to the cell wall through fusion with cell wall anchor proteins, has emerged as a promising and powerful method with diverse applications in biotechnology and biomedicine. Compared to classical intracellular or extracellular expression (secretion) systems, the cell surface display strategy stands out by eliminating the necessity for enzyme purification, overcoming substrate transport limitations, and demonstrating enhanced activity, stability, and selectivity. Unlike phage or bacterial surface display, the yeast surface display (YSD) system offers distinct advantages, including its large cell size, ease of culture and genetic manipulation, the use of generally regarded as safe (GRAS) host cell, the ability to ensure correct folding of complex eukaryotic proteins, and the potential for post-translational modifications. To date, YSD systems have found widespread applications in protein engineering, waste biorefineries, bioremediation, and the production of biocatalysts and biosensors. This review focuses on detailing various strategies and mechanisms for constructing YSD systems, providing a comprehensive overview of both fundamental principles and practical applications. Finally, the review outlines future perspectives for developing novel forms of YSD systems and explores potential applications in diverse fields.

Revolutionizing biocatalysis: A review on innovative design and applications of enzyme-immobilized microfluidic devices

Integrating microfluidic devices and enzymatic processes in biocatalysis is a rapidly advancing field with promising applications. This review explores various facets, including applications, scalability, techno-commercial implications, and environmental consequences. Enzyme-embedded microfluidic devices offer advantages such as compact dimensions, rapid heat transfer, and minimal reagent consumption, especially in pharmaceutical optically pure compound synthesis. Addressing scalability challenges involves strategies for uniform flow distribution and consistent residence time. Incorporation with downstream processing and biocatalytic reactions makes the overall process environmentally friendly. The review navigates challenges related to reaction kinetics, cofactor recycling, and techno-commercial aspects, highlighting cost-effectiveness, safety enhancements, and reduced energy consumption. The potential for automation and commercial-grade infrastructure is discussed, considering initial investments and long-term savings. The incorporation of machine learning in enzyme-embedded microfluidic devices advocates a blend of experimental and in-silico methods for optimization. This comprehensive review examines the advancements and challenges associated with these devices, focusing on their integration with enzyme immobilization techniques, the optimization of process parameters, and the techno-commercial considerations crucial for their widespread implementation. Furthermore, this review offers novel insights into strategies for overcoming limitations such as design complexities, laminar flow challenges, enzyme loading optimization, catalyst fouling, and multi-enzyme immobilization, highlighting the potential for sustainable and efficient enzymatic processes in various industries.

Ene-Reductase-Catalyzed Aromatization of Simple Cyclohexanones to Phenols

Direct aromatization of cyclohexanones to synthesize substituted phenols represents a significant challenge in modern synthetic chemistry. Herein, we describe a novel ene-reductase (TsER) catalytic system that converts substituted cyclohexanones into the corresponding phenols. This process involves the successive dehydrogenation of two saturated carbon-carbon bonds within the six-membered ring of cyclohexanones and utilizes molecular oxygen to drive the reaction cycle. It demonstrates a versatile and efficient approach for the synthesis of substituted phenols, providing a valuable complement to existing chemical methodologies.

Recent advances in emerging nanozymes with aggregation-induced emission

AIE luminogens (AIEgens) are a class of unique fluorescent molecules that exhibit significantly enhanced luminescence properties and excellent photostability in the aggregated state. Recently, it has been found that some AIEgens can produce reactive oxygen species, which means that they may have potential enzyme-like activities and are thus termed "AIEzymes". Consequently, the discovery and design of novel AIEgens with enzyme-like properties have emerged as a new and exciting research direction. Additionally, AIEgens can enhance the catalytic efficiency of traditional nanozymes by direct combination, thereby endowing the nanozymes with multifunctionality. In this regard, nanozymes with aggregation-induced emission (AIE) properties, which represents a win-win integration, not only take full advantage of the low cost and stability of nanozymes, but also incorporate the excellent biocompatibility and fluorescence properties of AIEgens. These synergistic compounds bring about new opportunities for various applications, making AIEzymes of interest in biomedical research, food analysis, environmental monitoring, and especially imaging-guided diagnostics. This review will provide an overview of the latest strategies and achievements in the rational design and preparation of AIEzymes, as well as current research trends, future challenges and prospective solutions. We expect that this work will encourage and motivate more people to study and explore AIEzymes to further promote their applications in various fields.

Machine learning-assisted amidase-catalytic enantioselectivity prediction and rational design of variants for improving enantioselectivity

Biocatalysis is an attractive approach for the synthesis of chiral pharmaceuticals and fine chemicals, but assessing and/or improving the enantioselectivity of biocatalyst towards target substrates is often time and resource intensive. Although machine learning has been used to reveal the underlying relationship between protein sequences and biocatalytic enantioselectivity, the establishment of substrate fitness space is usually disregarded by chemists and is still a challenge. Using 240 datasets collected in our previous works, we adopt chemistry and geometry descriptors and build random forest classification models for predicting the enantioselectivity of amidase towards new substrates. We further propose a heuristic strategy based on these models, by which the rational protein engineering can be efficiently performed to synthesize chiral compounds with higher ee values, and the optimized variant results in a 53-fold higher E-value comparing to the wild-type amidase. This data-driven methodology is expected to broaden the application of machine learning in biocatalysis research.

Noncanonical Amino Acids: Bringing New-to-Nature Functionalities to Biocatalysis

Biocatalysis has become an important component of modern organic chemistry, presenting an efficient and environmentally friendly approach to synthetic transformations. Advances in molecular biology, computational modeling, and protein engineering have unlocked the full potential of enzymes in various industrial applications. However, the inherent limitations of the natural building blocks have sparked a revolutionary shift. In vivo genetic incorporation of noncanonical amino acids exceeds the conventional 20 amino acids, opening new avenues for innovation. This review provides a comprehensive overview of applications of noncanonical amino acids in biocatalysis. We aim to examine the field from multiple perspectives, ranging from their impact on enzymatic reactions to the creation of novel active sites, and subsequent catalysis of new-to-nature reactions. Finally, we discuss the challenges, limitations, and promising opportunities within this dynamic research domain.

Biocatalytic approach for the synthesis of chiral alcohols for the development of pharmaceutical intermediates and other industrial applications: A review

Biocatalysis has emerged as a strong tool for the synthesis of active pharmaceutical ingredients (APIs). In the early twentieth century, whole cell biocatalysis was used to develop the first industrial biocatalytic processes, and the precise work of enzymes was unknown. Biocatalysis has evolved over the years into an essential tool for modern, cost-effective, and sustainable pharmaceutical manufacturing. Meanwhile, advances in directed evolution enable the rapid production of process-stable enzymes with broad substrate scope and high selectivity. Large-scale synthetic pathways incorporating biocatalytic critical steps towards >130 APIs of authorized pharmaceuticals and drug prospects are compared in terms of steps, reaction conditions, and scale with the corresponding chemical procedures. This review is designed on the functional group developed during the reaction forming alcohol functional groups. Some important biocatalyst sources, techniques, and challenges are described. A few APIs and their utilization in pharmaceutical drugs are explained here in this review. Biocatalysis has provided shorter, more efficient, and more sustainable alternative pathways toward existing small molecule APIs. Furthermore, non-pharmaceutical applications of biocatalysts are also mentioned and discussed. Finally, this review includes the future outlook and challenges of biocatalysis. In conclusion, Further research and development of promising enzymes are required before they can be used in industry.

High-efficient preparation of β-nicotinamide mononucleotides by crude enzymes cascade catalytic reaction

β-nicotinamide mononucleotide (β-NMN) is a key precursor of nicotinamide adenine dinucleotide, and becomes attractive in the nutrition and health care fields, but its enzymatic synthesis is expensive. In this study, a six-enzyme cascade catalytic system was constructed to produce β-NMN. Using D-ribose and nicotinamide as substrates, the β-NMN yield reached 97.5 % catalyzed by purified enzymes. Then, after knocking out the genes encoding proteins that consume β-NMN in E. coli BL21(DE3), the similar β-NMN yield, 97.2 %, using the crude enzymes could be also obtained. After that, β-NMN synthesis was performed under increased substrate concentration, and 'modular' crude enzymes cascade catalytic reaction system was proposed to reduce the inhibition of polyphosphate on ribose-phosphate diphosphokinase activity, and the β-NMN yield reached 78.4 % at 10 mM D-ribose, which is 1.82 times of that in 'one-pot' reaction and represents the highest β-NMN preparation level with phosphoribosylpyrophosphate as the core reported till now.

Enzyme purification and sustained enzyme activity for pharmaceutical biocatalysis by fusion with phase-separating intrinsically disordered protein

In recent decades, biocatalysis has emerged as an important alternative to chemical catalysis in pharmaceutical manufacturing. Biocatalysis is attractive because enzymatic cascades can synthesize complex molecules with incredible selectivity, yield, and in an environmentally benign manner. Enzymes for pharmaceutical biocatalysis are typically used in their unpurified state, since it is time-consuming and cost-prohibitive to purify enzymes using conventional chromatographic processes at scale. However, impurities present in crude enzyme preparations can consume substrate, generate unwanted byproducts, as well as make the isolation of desired products more cumbersome. Hence, a facile, nonchromatographic purification method would greatly benefit pharmaceutical biocatalysis. To address this issue, here we have captured enzymes into membraneless compartments by fusing enzymes with an intrinsically disordered protein region, the RGG domain from LAF-1. The RGG domain can undergo liquid-liquid phase separation, forming liquid condensates triggered by changes in temperature or salt concentration. By centrifuging these liquid condensates, we have successfully purified enzyme-RGG fusions, resulting in significantly enhanced purity compared to cell lysate. Furthermore, we performed enzymatic reactions utilizing purified fusion proteins to assay enzyme activity. Results from the enzyme assays indicate that enzyme-RGG fusions purified by the centrifugation method retain enzymatic activity, with greatly reduced background activity compared to crude enzyme preparations. Our work focused on three different enzymes-a kinase, a phosphorylase, and an ATP-dependent ligase. The kinase and phosphorylase are components of the biocatalytic cascade for manufacturing molnupiravir, and we demonstrated facile co-purification of these two enzymes by co-phase separation. To conclude, enzyme capture by RGG tagging promises to overcome difficulties in bioseparations and biocatalysis for pharmaceutical synthesis.

A tailored cytochrome P450 monooxygenase from Gordonia rubripertincta CWB2 for selective aliphatic monooxygenation

Cytochrome P450 monooxygenases are recognized as versatile biocatalysts due to their broad reaction capabilities. One important reaction is the hydroxylation of non-activated C-H bonds. The subfamily CYP153A is known for terminal hydroxylation reactions, giving access to functionalized aliphatics. Whilst fatty derivatives may be converted by numerous enzyme classes, midchain aliphatics are seldomly accepted, a prime property of CYP153As. We report here on a new CYP153A member from the genome of the mesophilic actinobacterium Gordonia rubripertincta CWB2 as an efficient biocatalyst. The gene was overexpressed in Escherichia coli and fused with a surrogate electron transport system from Acinetobacter sp. OC4. This chimeric self-sufficient whole-cell system could perform hydroxylation and epoxidation reactions: conversions of C6-C14 alkanes, alkenes, alcohols and of cyclic compounds were observed, yielding production rates of, e.g., 2.69 mM h-1 for 1-hexanol and 4.97 mM h-1 for 1,2-epoxyhexane. Optimizing the linker compositions between the protein units led to significantly altered activity. Balancing linker length and flexibility with glycine-rich and helix-forming linker units increased 1-hexanol production activity to 350 % compared to the initial linker setup with entirely helical linkers. The study shows that strategic coupling of efficient electron supply and a selective enzyme enables previously challenging monooxygenation reactions of midchain aliphatics.

Ceria nanoparticles immobilized with self-assembling peptide for biocatalytic applications

Peptide-based artificial enzymes exhibit structure and catalytic mechanisms comparable to natural enzymes but they suffer from limited reusability due to their existence in homogenous solutions. Immobilization of self-assembling peptides on the surface of nanoparticles can be used to overcome limitations associated with artificial enzymes. A high, local density of peptides can be obtained on nanoparticles to exert cooperative or synergistic effects, resulting in an accelerated rate of reaction, distinct catalytic properties, and excellent biocompatibility. In this work, we have immobilized a branched, self-assembled, and nanofibrous catalytic peptide, (C12-SHD)2KK(Alloc)-NH2, onto thiolated ceria nanoparticles to generate a heterogeneous catalyst with an enhanced number of catalytic sites. This artificial enzyme mimics the activities of esterase, phosphatase, and haloperoxidase enzymes and the catalytic efficiency remains nearly unaltered when reused. The enzyme-mimicking property is investigated for pesticide detection, bone regeneration, and antibiofouling applications. Overall, this work presents a facile approach to develop a multifunctional heterogeneous biocatalyst that addresses the challenges associated with unstable peptide-based homogeneous catalysts and, thus, shows a strong potential for industrial applications.

Structural Elucidation of a Metagenomic Urethanase and Its Engineering Towards Enhanced Hydrolysis Profiles

While plastics like polyethylene terephthalate can already be degraded efficiently by the activity of hydrolases, other synthetic polymers like polyurethanes (PUs) and polyamides (PAs) largely resist biodegradation. In this study, we solved the first crystal structure of the metagenomic urethanase UMG-SP-1, identified highly flexible loop regions to comprise active site residues, and targeted a total of 20 potential hot spots by site-saturation mutagenesis. Engineering campaigns yielded variants with single mutations, exhibiting almost 3- and 8-fold improved activity against highly stable N-aryl urethane and amide bonds, respectively. Furthermore, we demonstrated the release of the corresponding monomers from a thermoplastic polyester-PU and a PA (nylon 6) by the activity of a single, metagenome-derived urethanase after short incubation times. Thereby, we expanded the hydrolysis profile of UMG-SP-1 beyond the reported low-molecular weight carbamates. Together, these findings promise advanced strategies for the bio-based degradation and recycling of plastic materials and waste, aiding efforts to establish a circular economy for synthetic polymers.

Stereodivergent Total Synthesis of Tacaman Alkaloids

This paper describes a concise, asymmetric and stereodivergent total synthesis of tacaman alkaloids. A key step in this synthesis is the biocatalytic Baeyer-Villiger oxidation of cyclohexanone, which was developed to produce seven-membered lactones and establish the required stereochemistry at the C14 position (92 % yield, 99 % ee, 500 mg scale). Cis- and trans-tetracyclic indoloquinolizidine scaffolds were rapidly synthesized through an acid-triggered, tunable acyl-Pictet-Spengler type cyclization cascade, serving as the pivotal reaction for building the alkaloid skeleton. Computational results revealed that hydrogen bonding was crucial in stabilizing intermediates and inducing different addition reactions during the acyl-Pictet-Spengler cyclization cascade. By strategically using these two reactions and the late-stage diversification of the functionalized indoloquinolizidine core, the asymmetric total syntheses of eight tacaman alkaloids were achieved. This study may potentially advance research related to the medicinal chemistry of tacaman alkaloids.

Concluding remarks: biocatalysis

Biocatalysis is a rapidly evolving field with increasing impact in organic synthesis, chemical manufacturing and medicine. The Faraday Discussion reflected the current state of biocatalysis, covering the design of de novo enzymatic activities, but especially methods for the improvement of enzymes targeting a broad range of applications (i.e., hydroxylations by P450 monooxygenases, enzymatic deprotection of organic compounds under mild conditions, synthesis of chiral intermediates, plastic degradation, silicone polymer synthesis, and peptide synthesis). Central themes have been how to improve an enzyme using methods of rational design and directed evolution, informed by computer modelling and machine learning, and the incorporation of new catalytic functionalities to create hybrid and artificial enzymes.

Exploring the selectivity of cytochrome P450 for enhanced novel anticancer agent synthesis

Cytochrome P450 monooxygenases are an extensive and unique class of enzymes, which can regio- and stereo-selectively functionalise hydrocarbons by way of oxidation reactions. These enzymes are naturally occurring but have also been extensively applied in a synthesis context, where they are used as efficient biocatalysts. Recently, a biosynthetic pathway where a cytochrome P450 monooxygenase catalyses a critical step of the pathway was uncovered, leading to the production of a number of products that display high antitumour potency. In this work, we use computational techniques to gain insight into the factors that determine the relative yields of the different products. We use conformational search algorithms to understand the substrate stereochemistry. On a machine-learned 3D protein structure, we use molecular docking to obtain a library of favourable poses for substrate-protein interaction. With molecular dynamics, we investigate the most favourable poses for reactivity on a molecular level, allowing us to investigate which protein-substrate interactions favour a given product and thus gain insight into the product selectivity.

Learning from Protein Engineering by Deconvolution of Multi-Mutational Variants

This review analyzes a development in biochemistry, enzymology and biotechnology that originally came as a surprise. Following the establishment of directed evolution of stereoselective enzymes in organic chemistry, the concept of partial or complete deconvolution of selective multi-mutational variants was introduced. Early deconvolution experiments of stereoselective variants led to the finding that mutations can interact cooperatively or antagonistically with one another, not just additively. During the past decade, this phenomenon was shown to be general. In some studies, molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) computations were performed in order to shed light on the origin of non-additivity at all stages of an evolutionary upward climb. Data of complete deconvolution can be used to construct unique multi-dimensional rugged fitness pathway landscapes, which provide mechanistic insights different from traditional fitness landscapes. Along a related line, biochemists have long tested the result of introducing two point mutations in an enzyme for mechanistic reasons, followed by a comparison of the respective double mutant in so-called double mutant cycles, which originally showed only additive effects, but more recently also uncovered cooperative and antagonistic non-additive effects. We conclude with suggestions for future work, and call for a unified overall picture of non-additivity and epistasis.

Enzyme-mediated green synthesis of glycosaminoglycans and catalytic process intensification

Glycosaminoglycans (GAGs) are a family of structurally complex heteropolysaccharides that play pivotal roles in biological functions, including the regulation of cell proliferation, enzyme inhibition, and activation of growth factor receptors. Therefore, the synthesis of GAGs is a hot research topic in drug development. The enzymatic synthesis of GAGs has received widespread attention due to their eco-friendly nature, high regioselectivity, and stereoselectivity. The enhancement of the enzymatic synthesis process is the key to its industrial applications. In this review, we overviewed the construction of more efficient in vitro biomimetic synthesis systems of glycosaminoglycans and presented the different strategies to improve enzyme catalysis, including the combination of chemical and enzymatic methods, solid-phase synthesis, and protein engineering to solve the problems of enzyme stability, separation and purification of the product, preparation of structurally defined sugar chains, etc., and discussed the challenges and opportunities in large-scale green synthesis of GAGs.

Hosts engineering and in vitro enzymatic synthesis for the discovery of novel natural products and their derivatives

Novel natural products (NPs) and their derivatives are important sources for drug discovery, which have been broadly applied in the fields of agriculture, livestock, and medicine, making the synthesis of NPs and their derivatives necessarily important. In recent years, biosynthesis technology has received increasing attention due to its high efficiency in the synthesis of high value-added novel products and its advantages of green, environmental protection, and controllability. In this review, the technological advances of biosynthesis strategies in the discovery of novel NPs and their derivatives are outlined, with an emphasis on two areas of host engineering and in vitro enzymatic synthesis. In terms of hosts engineering, multiple microorganisms, including Streptomyces, Aspergillus, and Penicillium, have been used as the biosynthetic gene clusters (BGCs) provider and host strain for the expression of BGCs to discover new compounds over the past years. In addition, the use of in vitro enzymatic synthesis strategy to generate novel compounds such as triterpenoid saponins and flavonoids is also hereby described.

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

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

Reversible and size-controlled assembly of reflectin proteins using a charged azobenzene photoswitch

Disordered proteins often undergo a stimuli-responsive, disorder-to-order transition which facilitates dynamic processes that modulate the physiological activities and material properties of cells, such as strength, chemical composition, and reflectance. It remains challenging to gain rapid and spatiotemporal control over such disorder-to-order transitions, which limits the incorporation of these proteins into novel materials. The reflectin protein is a cationic, disordered protein whose assembly is responsible for dynamic color camouflage in cephalopods. Stimuli-responsive control of reflectin's assembly would enable the design of biophotonic materials with tunable color. Herein, a novel, multivalent azobenzene photoswitch is shown to be an effective and non-invasive strategy for co-assembling with reflectin molecules and reversibly controlling assembly size. Photoisomerization between the trans and cis (E and Z) photoisomers promotes or reduces Coulombic interactions, respectively, with reflectin proteins to repeatedly cycle the sizes of the photoswitch-reflectin assemblies between 70 nm and 40 nm. The protein assemblies formed with the trans and cis isomers show differences in interaction stoichiometry and secondary structure, which indicate that photoisomerization modulates the photoswitch-protein interactions to change assembly size. Our results highlight the utility of photoswitchable interactions to control reflectin assembly and provide a tunable synthetic platform that can be adapted to the structure, assembly, and function of other disordered proteins.

Crystallization Assisted Dynamic Kinetic Resolution for the Synthesis of (R)-β-Methylphenethylamine

This study explores a combination of the concept of enantioselective enzymatic synthesis of β-chiral amines through transamination with in situ product crystallization (ISPC) to overcome product inhibition. Using 2-phenylpropanal as a readily available and easily racemizing substrate of choice, (R)-β-methylphenethylamine ((R)-2-phenylpropan-1-amine) concentrations of up to 250 mM and enantiomeric excesses of up to 99 % are achieved when using a commercially available transaminase from Ruegeria pomeroyi in a fed-batch based dynamic kinetic resolution reaction on preparative scale. The source of substrate decomposition during the reaction is also investigated and the resulting unwanted byproduct formation is successfully reduced to insignificant levels.

Navigating the landscape of enzyme design: from molecular simulations to machine learning

Global environmental issues and sustainable development call for new technologies for fine chemical synthesis and waste valorization. Biocatalysis has attracted great attention as the alternative to the traditional organic synthesis. However, it is challenging to navigate the vast sequence space to identify those proteins with admirable biocatalytic functions. The recent development of deep-learning based structure prediction methods such as AlphaFold2 reinforced by different computational simulations or multiscale calculations has largely expanded the 3D structure databases and enabled structure-based design. While structure-based approaches shed light on site-specific enzyme engineering, they are not suitable for large-scale screening of potential biocatalysts. Effective utilization of big data using machine learning techniques opens up a new era for accelerated predictions. Here, we review the approaches and applications of structure-based and machine-learning guided enzyme design. We also provide our view on the challenges and perspectives on effectively employing enzyme design approaches integrating traditional molecular simulations and machine learning, and the importance of database construction and algorithm development in attaining predictive ML models to explore the sequence fitness landscape for the design of admirable biocatalysts.

Functional characterization, structural basis, and protein engineering of a rare flavonoid 2'-O-glycosyltransferase from Scutellaria baicalensis

Glycosylation is an important post-modification reaction in plant secondary metabolism, and contributes to structural diversity of bioactive natural products. In plants, glycosylation is usually catalyzed by UDP-glycosyltransferases. Flavonoid 2'-O-glycosides are rare glycosides. However, no UGTs have been reported, thus far, to specifically catalyze 2'-O-glycosylation of flavonoids. In this work, UGT71AP2 was identified from the medicinal plant Scutellaria baicalensis as the first flavonoid 2'-O-glycosyltransferase. It could preferentially transfer a glycosyl moiety to 2'-hydroxy of at least nine flavonoids to yield six new compounds. Some of the 2'-O-glycosides showed noticeable inhibitory activities against cyclooxygenase 2. The crystal structure of UGT71AP2 (2.15 Å) was solved, and mechanisms of its regio-selectivity was interpreted by pK a calculations, molecular docking, MD simulation, MM/GBSA binding free energy, QM/MM, and hydrogen‒deuterium exchange mass spectrometry analysis. Through structure-guided rational design, we obtained the L138T/V179D/M180T mutant with remarkably enhanced regio-selectivity (the ratio of 7-O-glycosylation byproducts decreased from 48% to 4%) and catalytic efficiency of 2'-O-glycosylation (k cat/K m, 0.23 L/(s·μmol), 12-fold higher than the native). Moreover, UGT71AP2 also possesses moderate UDP-dependent de-glycosylation activity, and is a dual function glycosyltransferase. This work provides an efficient biocatalyst and sets a good example for protein engineering to optimize enzyme catalytic features through rational design.

Rational redesign of the loop dynamics of carbonyl reductase LfSDR1 to improve the stereoselectivity for asymmetric synthesis of bulky chiral alcohols

Engineering biocatalysts with enhanced stereoselectivity is highly desirable, and active-site loop dynamics play an important role in its regulation. However, knowledge of their precise roles in catalysis and evolution is limited. Here, we used the strategy of Rosetta enzyme design combined molecular dynamic simulations (MDs) to reprogram the landscapes of the key active-site loop dynamics of the carbonyl reductase LfSDR1 to improve stereoselectivity. The key flexible loop in the active site showed the potential to regulate the catalytic properties. A library of virtual variants was produced using the Rosetta design and assessed dynamic effect of the loop with the aid of MDs. A potential candidate was obtained with significant stereoselectivity (ee > 99 %) compared to the wild-type (ee = 42 %) without loss of catalytic activity or thermostability. The molecular basis of the catalytic property enhancement was flanked by MDs, which revealed the role of the G92L mutation in regulating loop dynamics to stabilize the environment of the active site. Finally, a series of the challenge bulky substrate derivatives were assessed using the G92L variant, and all showed improved stereoselectivity ee > 99 %. This study provides novel insights for improving stereoselectivity through rational engineering of the loop dynamics of biocatalysts.

Efficient Enzymatic Synthesis of Carbamates in Water Using Promiscuous Esterases/Acyltransferases

Biocatalysis provides an attractive approach to facilitate synthetic reactions in aqueous media. Motivated by the discovery of promiscuous aminolysis activity of esterases, we exploited the esterase from Pyrobaculum calidifontis VA1 (PestE) for the synthesis of carbamates from different aliphatic, aromatic, and arylaliphatic amines and a set of carbonates such as dimethyl-, dibenzyl-, or diallyl carbonate. Thus, aniline and benzylamine derivatives, aliphatic and even secondary amines could be efficiently converted into the corresponding benzyloxycarbonyl (Cbz)- or allyloxycarbonyl (Alloc)-protected products in bulk water, with (isolated) yields of up to 99 %.

Monitoring Enzymatic Reaction Kinetics and Activity Assays in Confined Nanospace

Enzyme-mediating biotransformations commonly occur in micro- and nanospace, which is crucial to maintain the essential biochemical processes and physiological functions in living systems. Probing enzyme-catalytic reactions in a biomimetic fashion remains challenging due to the lack of competent tools and methodology. Here, we show that studying enzymatic reaction kinetics can be readily achieved by a well-designed solid-state nanopore. Using tyrosine as a classical substrate, we quantitatively characterize the catalytic activity of tyrosinase (TYR) and tyrosine decarboxylase (TDC) in a nanoconfined space. Tyrosine was first immobilized in the nanopipette, wherein the active sites of tyrosine were left unoccupied. When successively exposed to TYR and TDC, a two-step cascade reaction can spontaneously take place. In this process, the surface wettability and charge of the nanopipette stemming from the catalytic products can sensitively regulate ion transport and ionic current rectification behavior, which were monitored by ionic current signal. In this biomimetic scenario, we obtained the enzymatic reaction kinetics of monophenyl oxidase that were not previously actualized in the conventional macroenvironment. Significantly, TYR showed higher enzyme activity, with a Km value of 1.59 mM, which was lower than that measured in a free and open space (with a Km of 3.01 mM). This suggests that tyrosine should be the most appropriate substrate of TYR, thus improving our understanding of tyrosine-associated biochemical reactions. This work offers an applicable technical platform to mimic enzyme-mediated biotransformations and biometabolisms.

Site-directed display of zearalenone lactonase on spilt-intein functionalized nanocarrier for green and efficient detoxification of zearalenone

In this study, we prepared a functional organic-inorganic hybrid nanoflower (InHNF) via split intein moiety in a biomineralization process without using organic solvents. InHNF could specifically bind the target enzymes from crude cell lysates within seconds and site-directedly display them on the surface by forming a peptide bond with enzyme's terminal amino acid residue. This unique feature enabled InHNF to increase the specific activity of zearalenone detoxifying enzyme ZHD518 by 40 ∼ 60% at all tested temperatures and prevented enzyme denaturation even under extreme pH conditions (pH 3-11). Furthermore, it exhibited excellent operational stability, with a residual activity of over 70% after eight reaction cycles. Strikingly, InHNF-ZHD518 achieved above 50% ZEN degradation despite the near inactivation of free ZHD518 in beer sample. Overall, InHNF nanocarriers can achieve environmentally friendly, purification-free, and site-directed immobilization of food enzymes and enhance their catalytic properties, making them suitable for a wide range of industrial applications.

The Development and Opportunities of Predictive Biotechnology

Recent advances in bioeconomy allow a holistic view of existing and new process chains and enable novel production routines continuously advanced by academia and industry. All this progress benefits from a growing number of prediction tools that have found their way into the field. For example, automated genome annotations, tools for building model structures of proteins, and structural protein prediction methods such as AlphaFold2TM or RoseTTAFold have gained popularity in recent years. Recently, it has become apparent that more and more AI-based tools are being developed and used for biocatalysis and biotechnology. This is an excellent opportunity for academia and industry to accelerate advancements in the field further. Biotechnology, as a rapidly growing interdisciplinary field, stands to benefit greatly from these developments.

Re-assessing viologens for modern bio-electrocatalysis

Viologens, 1,1'-disubstituted-4,4'-bipyridinium salts, are organic redox species that can be used in place of NADPH as mediators for redox enzymes. In this study, using the reduction of oxidized glutathione by glutathione reductase as a model system, a rationally designed library of viologens covering a range of polarities and functional groups were explored as electron transfer mediators for bio-electrocatalysis. Through a series of electrochemical investigations, the reduction potential was found to be the primary determining factor for electron transfer between the viologen and enzyme. Through enhancing the solubility of viologen such that the fully reduced state remained soluble, we demonstrate a much-widened window of useable viologen potentials. In doing so, we describe for the first time a highly efficient electron transfer to a flavoenzyme promoting the catalytic reaction in the absence of co-factors. As such, our study provides a platform for broadening the scope for using viologens as mediating agents for electrochemically-driven enzymatic processes.