Design of a Pd(0)-CalB CLEA Biohybrid Catalyst and Its Application in a One-Pot Cascade Reaction

In Situ Enzymatic Polymerization of Ethylene Brassylate Mediated by Artificial Plant Cell Walls in Reactive Extrusion

Herein, we describe a solvent-free bioinspired approach for the polymerization of ethylene brassylate. Artificial plant cell walls (APCWs) with an integrated enzyme were fabricated by self-assembly, using microcrystalline cellulose as the main structural component. The resulting APCW catalysts were tested in bulk reactions and reactive extrusion, leading to high monomer conversion and a molar mass of around 4 kDa. In addition, we discovered that APCW catalyzes the formation of large ethylene brassylate macrocycles. The enzymatic stability and efficiency of the APCW were investigated by recycling the catalyst both in bulk and reactive extrusion. The obtained poly(ethylene brassylate) was applied as a biobased and biodegradable hydrophobic paper coating.

One-pot chemo- and photo-enzymatic linear cascade processes

The combination of chemo- and photocatalyses with biocatalysis, which couples the flexible reactivity of the photo- and chemocatalysts with the highly selective and environmentally friendly nature of enzymes in one-pot linear cascades, represents a powerful tool in organic synthesis. However, the combination of photo-, chemo- and biocatalysts in one-pot is challenging because the optimal operating conditions of the involved catalyst types may be rather different, and the different stabilities of catalysts and their mutual deactivation are additional problems often encountered in one-pot cascade processes. This review explores a large number of transformations and approaches adopted for combining enzymes and chemo- and photocatalytic processes in a successful way to achieve valuable chemicals and valorisation of biomass. Moreover, the strategies for solving incompatibility issues in chemo-enzymatic reactions are analysed, introducing recent examples of the application of non-conventional solvents, enzyme-metal hybrid catalysts, and spatial compartmentalization strategies to implement chemo-enzymatic cascade processes.

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.

Tuning Chemoenzymatic Pd/Laccase Conformation Toward Optimized Heterogeneous Aerobic Oxidation

Heterogeneous chemoenzymatic catalysts differing in their spatial organization and relative orientation of their enzymatic laccase and Pd units confined into macrocellular silica foams were tested on veratryl alcohol oxidation. When operating under continuous flow, we show that the catalytic efficiency of hybrids is significantly enhanced when the Pd(II) complex is combined with a laccase exhibiting a surface located lysine next to the T1 oxidation site of the enzyme.

Opportunities and Challenges of Metal-Organic Framework Micro/Nano Reactors for Cascade Reactions

Building bridges among different types of catalysts to construct cascades is a highly worthwhile pursuit, such as chemo-, bio-, and chemo-bio cascade reactions. Cascade reactions can improve the reaction efficiency and selectivity while reducing steps of separation and purification, thereby promoting the development of "green chemistry". However, compatibility issues in cascade reactions pose significant constraints on the development of this field, particularly concerning the compatibility of diverse catalyst types, reaction conditions, and reaction rates. Metal-organic framework micro/nano reactors (MOF-MNRs) are porous crystalline materials formed by the self-assembly coordination of metal sites and organic ligands, possessing a periodic network structure. Due to the uniform pore size with the capability of controlling selective transfer of substances as well as protecting active substances and the organic-inorganic parts providing reactive microenvironment, MOF-MNRs have attracted significant attention in cascade reactions in recent years. In this Perspective, we first discuss how to address compatibility issues in cascade reactions using MOF-MNRs, including structural design and synthetic strategies. Then we summarize the research progress on MOF-MNRs in various cascade reactions. Finally, we analyze the challenges facing MOF-MNRs and potential breakthrough directions and opportunities for the future.

Cellulose-Supported Heterogeneous Gold-Catalyzed Cycloisomerization Reactions of Alkynoic Acids and Allenynamides

Herein, we describe efficient nanogold-catalyzed cycloisomerization reactions of alkynoic acids and allenynamides to enol lactones and dihydropyrroles, respectively (the latter via an Alder-ene reaction). The gold nanoparticles were immobilized on thiol-functionalized microcrystalline cellulose and characterized by electron microscopy (HAADF-STEM) and by XPS. The thiol-stabilized gold nanoparticles (Au0) were obtained in the size range 1.5-6 nm at the cellulose surface. The robust and sustainable cellulose-supported gold nanocatalyst can be recycled for multiple cycles without losing activity.

Subtilisin integrated artificial plant cell walls as heterogeneous catalysts for asymmetric synthesis of (S)-amides

Subtilisin integrated artificial plant-cell walls (APCWs) were fabricated by self-assembly using cellulose or nanocellulose as the main component. The resulting APCW catalysts are excellent heterogeneous catalysts for the asymmetric synthesis of (S)-amides. This was demonstrated by the APCW-catalyzed kinetic resolution of several racemic primary amines to give the corresponding (S)-amides in high yields with excellent enantioselectivity. The APCW catalyst can be recycled for multiple reaction cycles without loss of enantioselectivity. The assembled APCW catalyst was also able to cooperate with a homogeneous organoruthenium complex, which allowed for the co-catalytic dynamic kinetic resolution (DKR) of a racemic primary amine to give the corresponding (S)-amide in high yield. The APCW/Ru co-catalysis constitutes the first examples of DKR of chiral primary amines when subtilisin is used as a co-catalyst.

Integration of chemo- and bio-catalysis to intensify bioprocesses

Nature has evolved highly efficient and complex systems to perform cascade reactions by the elegant combination of desired enzymes, offering a strategy for achieving efficient bioprocess intensification. Chemoenzymatic cascade reactions (CECRs) merge the complementary strengths of chemo-catalysis and bio-catalysis, such as the wide reactivity of chemo-catalysts and the exquisite selective properties of biocatalysts, representing an important step toward emulating nature to construct artificial systems for achieving bioprocess intensification. However, the incompatibilities between the two catalytic disciplines make CECRs highly challenging. In recent years, great advances have been made to develop strategies for constructing CECRs. In this regard, this chapter introduces the general concepts and representative strategies, including temporal compartmentalization, spatial compartmentalization and chemo-bio nanoreactors. Particularly, we focus on what platform methods and technologies can be used, and how to implement these strategies. The future challenges and strategies in this burgeoning research area are also discussed.

Protein-supported transition metal catalysts: Preparation, catalytic applications, and prospects

The immobilization of transition metal catalysts onto supports enables their easier recycling and improves catalytic performance. Protein supports not only support and stabilize transition metal catalysts but also enable the incorporation of biocompatibility and enzymatic catalysis into these catalysts. Consequently, the engineering of protein-supported transition metal catalysts (PTMCs) has emerged as an effective approach to improving their catalytic performance and widening their catalytic applications. Here, we review the recent development of the preparation and applications of PTMCs. The preparation of PTMCs will be summarized and discussed in terms of the types of protein supports, including proteins, protein assemblies, protein-polymer conjugates, and cross-linked proteins. Then, their catalytic applications including organic synthesis, photocatalysis, polymerization, and biomedicine, will be surveyed and compared. Meanwhile, the established catalytic structures-function relationships will be summarized. Lastly, the remaining issues and prospects will be discussed. By surveying a wide range of PTMCs, we believe that this review will attract a broad readership and stimulate the development of PTMCs.

Expanding the Synthetic Toolbox through Metal-Enzyme Cascade Reactions

The combination of metal-, photo-, enzyme-, and/or organocatalysis provides multiple synthetic solutions, especially when the creation of chiral centers is involved. Historically, enzymes and transition metal species have been exploited simultaneously through dynamic kinetic resolutions of racemates. However, more recently, linear cascades have appeared as elegant solutions for the preparation of valuable organic molecules combining multiple bioprocesses and metal-catalyzed transformations. Many advantages are derived from this symbiosis, although there are still bottlenecks to be addressed including the successful coexistence of both catalyst types, the need for compatible reaction media and mild conditions, or the minimization of cross-reactivities. Therefore, solutions are here also provided by means of catalyst coimmobilization, compartmentalization strategies, flow chemistry, etc. A comprehensive review is presented focusing on the period 2015 to early 2022, which has been divided into two main sections that comprise first the use of metals and enzymes as independent catalysts but working in an orchestral or sequential manner, and later their application as bionanohybrid materials through their coimmobilization in adequate supports. Each part has been classified into different subheadings, the first part based on the reaction catalyzed by the metal catalyst, while the development of nonasymmetric or stereoselective processes was considered for the bionanohybrid section.

Artificial plant cell walls as multi-catalyst systems for enzymatic cooperative asymmetric catalysis in non-aqueous media

The assembly of cellulose-based artificial plant cell wall (APCW) structures that contain different types of catalysts is a powerful strategy for the development of cascade reactions. Here we disclose an APCW catalytic system containing a lipase enzyme and nanopalladium particles that transform a racemic amine into the corresponding enantiomerically pure amide in high yield via a dynamic kinetic resolution.

Palladium in biological media: Can the synthetic chemist's most versatile transition metal become a powerful biological tool?

Palladium catalysed reactions are ubiquitous in synthetic organic chemistry in both organic solvents and aqueous buffers. The broad reactivity of palladium catalysis has drawn interest as a means to conduct orthogonal transformations in biological settings. Successful examples have been shown for protein modification, in vivo drug decaging and as palladium-protein biohybrid catalysts for selective catalysis. Biological media represents a challenging environment for palladium chemistry due to the presence of a multitude of chelators, catalyst poisons and a requirement for milder reaction conditions e.g. lower temperatures. This review looks to identify successful examples of palladium-catalysed reactions in the presence of proteins or cells and analyse solutions to help to overcome the challenges of working in biological systems.

Enzyme-Metal Hybrid Catalysts for Chemoenzymatic Reactions

Enzyme-metal hybrid catalysts (EMHCs), which combine enzymatic and metal catalysis, provide tremendous possibilities for new chemoenzymatic cascade reactions. Here, an overview of the representative achievements in the design of EMHCs and their applications in chemoenzymatic cascade reactions are presented. The preparation of hybrid catalysts is classified into two categories: coimmobilized enzyme-metal heterogeneous catalysts and carrier-free enzyme-metal bioconjugates. Examples of one-pot chemoenzymatic cascade processes catalyzed by the hybrid catalysts are then provided as potential applications. Finally, the limitations and future perspectives of EMHCs are discussed.

Recent Advances in Enzyme-Nanostructure Biocatalysts with Enhanced Activity

Owing to their unique physicochemical properties and comparable size to biomacromolecules, functional nanostructures have served as powerful supports to construct enzyme-nanostructure biocatalysts (nanobiocatalysts). Of particular importance, recent years have witnessed the development of novel nanobiocatalysts with remarkably increased enzyme activities. This review provides a comprehensive description of recent advances in the field of nanobiocatalysts, with systematic elaboration of the underlying mechanisms of activity enhancement, including metal ion activation, electron transfer, morphology effects, mass transfer limitations, and conformation changes. The nanobiocatalysts highlighted here are expected to provide an insight into enzyme–nanostructure interaction, and provide a guideline for future design of high-efficiency nanobiocatalysts in both fundamental research and practical applications.

DESign of Sustainable One-Pot Chemoenzymatic Organic Transformations in Deep Eutectic Solvents for the Synthesis of 1,2-Disubstituted Aromatic Olefins

The self-assembly of styrene-type olefins into the corresponding stilbenes was conveniently performed in the Deep Eutectic Solvent (DES) mixture 1ChCl/2Gly under air and in the absence of hazardous organic co-solvents using a one-pot chemo-biocatalytic route. Here, an enzymatic decarboxylation of p-hydroxycinnamic acids sequentially followed by a ruthenium-catalyzed metathesis of olefins has been investigated in DES. Moreover, and to extend the design of chemoenzymatic processes in DESs, we also coupled the aforementioned enzymatic decarboxylation reaction to now concomitant Pd-catalyzed Heck-type C-C coupling to produce biaryl derivatives under environmentally friendly reaction conditions.

The various levels of integration of chemo- and bio-catalysis towards hybrid catalysis

Hybrid catalysis is an emerging concept that combines chemo- and biocatalysts in a wide variety of approaches. Combining the specifications and advantages of multiple disciplines, it is a very promising way to diversify tomorrow's catalysis.

Hollow zeolite microspheres as a nest for enzymes: a new route to hybrid heterogeneous catalysts

In the field of heterogeneous catalysis, the successful integration of enzymes and inorganic catalysts could pave the way to multifunctional materials which are able to perform advanced cascade reactions. However, such combination is not straightforward, for example in the case of zeolite catalysts for which enzyme immobilization is restricted to the external surface. Herein, this challenge is overcome by developing a new kind of hybrid catalyst based on hollow zeolite microspheres obtained by the aerosol-assisted assembly of zeolite nanocrystals. The latter spheres possess open entry-ways for enzymes, which are then loaded and cross-linked to form cross-linked enzyme aggregates (CLEAs), securing their entrapment. This controlled design allows the combination of all the decisive features of the zeolite with a high enzyme loading. A chemo-enzymatic reaction is demonstrated, where the structured zeolite material is used both as a nest for the enzyme and as an efficient inorganic catalyst. Glucose oxidase (GOx) ensures the in situ production of H2O2 subsequently utilized by the TS-1 zeolite to catalyze the epoxidation of allylic alcohol toward glycidol. The strategy can also be used to entrap other enzymes or combination of enzymes, as demonstrated here with combi-CLEAs of horseradish peroxidase (HRP) and glucose oxidase. We anticipate that this strategy will open up new perspectives, leveraging on the spray-drying (aerosol) technique to shape microparticles from various nano-building blocks and on the entrapment of biological macromolecules to obtain new multifunctional hybrid microstructures.

Self-assembly of lipase hybrid nanoflowers with bifunctional Ca2+ for improved activity and stability

Lipase ZC12, a cold-adapted lipase derived from Psychrobacter sp. ZY124, can be effectively activated by Ca²⁺. Inspired by this significant property, we developed a novel immobilized lipase ZC12/Ca₃(PO₄)₂ hybrid nanoflowers (LHNs). The LHNs have been characterized as a regular hierarchical flowerlike structure nanoflowers by scanning electron microscopy (SEM). Compared with free lipase ZC12, the LHNs exerted enhanced enzymatic activity of 206% and 2.31-fold in k_cat/K_m value, especially high specific activity at low temperature. After 7 successive cycles, the LHNs could still maintain its initial activity, demonstrating superior durability than the free lipase ZC12. Meanwhile, its stability basically kept unchanged in a wide range of temperature and pH. Finally, fructose laurate was transformed by the LHNs with 57.39% conversion rate which is twice as much as the free lipase. To sum up, these results validated that LHNs could emerge as an efficient immobilized lipase and possess the promising potential for practical applications.

Nanobiohybrids: a new concept for metal nanoparticles synthesis

In recent years, nanoscience and nanotechnology have brought a great revolution in different areas. In particular, the synthesis of transition metal nanoparticles has been of great relevance for their use in areas such as biomedicine, antimicrobial properties or catalytic applications for chemical synthesis. Recently, an innovative straightforward and very efficient synthesis of these nanoparticles by simply using enzymes as inductors in aqueous media has been described. This represents a very green alternative to the different methodologies described in the literature for metal nanoparticles preparation where harsh conditions are necessary. In this review the most recent advances in the synthesis of metal nanoparticles by this green technology, explaining the synthetic mechanism, the role of the enzyme in the formation of the nanoparticles and the effect on the final properties of these nanoparticles, are summarised. The application of these novel metal nanoparticles-enzyme hybrids in synthetic chemistry as heterogeneous catalysts with metal or dual (enzymatic and metallic) activity and their capacity as environmental and antimicrobial agents have also been discussed.

Broadening the Scope of Biocatalysis in Sustainable Organic Synthesis

This Review is aimed at synthetic organic chemists who may be familiar with organometallic catalysis but have no experience with biocatalysis, and seeks to provide an answer to the perennial question: if it is so attractive, why wasn't it extensively used in the past? The development of biocatalysis in industrial organic synthesis is traced from the middle of the last century. Advances in molecular biology in the last two decades, in particular genome sequencing, gene synthesis and directed evolution of proteins, have enabled remarkable improvements in scope and substantially reduced biocatalyst development times and cost contributions. Additionally, improvements in biocatalyst recovery and reuse have been facilitated by developments in enzyme immobilization technologies. Biocatalysis has become eminently competitive with chemocatalysis and the biocatalytic production of important pharmaceutical intermediates, such as enantiopure alcohols and amines, has become mainstream organic synthesis. The synthetic space of biocatalysis has significantly expanded and is currently being extended even further to include new-to-nature biocatalytic reactions.

Directed Evolution of Artificial Metalloenzymes: A Universal Means to Tune the Selectivity of Transition Metal Catalysts?

Transition metal catalysts mediate a wide variety of chemo-, stereo-, and regioselective transformations, and therefore play a pivotal role in modern synthetic organic chemistry. Steric and electronic effects of ligands provide organic chemists with an exceedingly useful tool. More than four decades ago, chemists began to think about a different approach, namely, embedding achiral ligand/metal moieties covalently or noncovalently in protein hosts with formation of artificial metalloenzymes. While structurally fascinating, this approach led in each case only to a single (bio)catalyst, with its selectivity and activity being a matter of chance. In order to solve this fundamental problem, my group proposed in 2000-2002 the idea of directed evolution of artificial metalloenzymes. In earlier studies, we had already demonstrated that directed evolution of enzymes constitutes a viable method for enhancing and inverting the stereoselectivity of enzymes as catalysts in organic chemistry. We speculated that it should also be possible to manipulate selectivity and activity of artificial metalloenzymes, which would provide organic chemists with a tool for optimizing essentially any transition metal catalyzed reaction type. In order to put this vision into practice, we first turned to the Whitesides system for artificial metalloenzyme formation, comprising a biotinylated diphosphine/Rh moiety, which is anchored noncovalently to avidin or streptavidin. Following intensive optimization, proof of principle was finally demonstrated in 2006, which opened the door to a new research area. This personal Account critically assesses these early studies as well as subsequent efforts from my group focusing on different protein scaffolds, and includes briefly some of the most important current contributions of other groups. Two primary messages emerge: First, since organic chemists continue to be extremely good at designing and implementing man-made transition metal catalysts, often on a large scale, those scientists that are active in the equally intriguing field of directed evolution of artificial metalloenzymes should be moderate when generalizing claims. All factors required for a truly viable catalytic system need to be considered, especially activity and ease of upscaling. Second, the most exciting and thus far very rare cases of directed evolution of artificial metalloenzymes are those that focus on selective transformations that are not readily possible using state of the art transition metal catalysts.

Self-Assembly of Nanoparticles in a Modular Fashion to Prepare Multifunctional Catalysts for Cascade Reactions: From Simplicity to Complexity

One-pot cascade reactions can simplify the synthetic route and reduce the use of solvents and energy. The critical part of the completion of the cascade reaction is the preparation of multifunctional catalysts. In this work, a novel and simple pathway was developed to construct multifunctional catalysts with acidic, basic, and magnetic properties at the same time. Mesoporous silica materials modified with different metal oxides were used as catalytic elements. Microspheres that assembled with catalytic components have a diameter of 150 μm and a specific surface area larger than 400 m² g^-1 and can be used as catalysts for cascade reactions. The yield of the final product in the deacetalization-Knoevenagel reaction is 92%. Microspheres integrated with Fe₃O₄ nanoparticles have a magnetic susceptibility of 7.2 emu g^-1 and can be easily removed from the reaction system by applying an external magnetic field. This multimodule assembly method fully reflects the enormous power of complexity resulting from simplicity. This method provides a reference and practical technical support for the preparation of other multifunctional materials.

The limits to biocatalysis: pushing the envelope

In the period 1985 to 1995 applications of biocatalysis, driven by the need for more sustainable manufacture of chemicals and catalytic, (enantio)selective methods for the synthesis of pharmaceutical intermediates, largely involved the available hydrolases. This was followed, in the next two decades, by revolutionary developments in protein engineering and directed evolution for the optimisation of enzyme function and performance that totally changed the biocatalysis landscape. In the same period, metabolic engineering and synthetic biology revolutionised the use of whole cell biocatalysis in the synthesis of commodity chemicals by fermentation. In particular, developments in the enzymatic enantioselective synthesis of chiral alcohols and amines are highlighted. Progress in enzyme immobilisation facilitated applications under harsh industrial conditions, such as in organic solvents. The emergence of biocatalytic or chemoenzymatic cascade processes, often with co-immobilised enzymes, has enabled telescoping of multi-step processes. Discovering and inventing new biocatalytic processes, based on (meta)genomic sequencing, evolving enzyme promiscuity, chemomimetic biocatalysis, artificial metalloenzymes, and the introduction of non-canonical amino acids into proteins, are pushing back the limits of biocatalysis function. Finally, the integral role of biocatalysis in developing a biobased carbon-neutral economy is discussed.

Ru/UiO-66 Catalyst for the Reduction of Nitroarenes and Tandem Reaction of Alcohol Oxidation/Knoevenagel Condensation

A 3.1% Ru/UiO-66 material was prepared by adsorption of RuCl₃ from ethyl acetate on to MOF UiO-66, followed by reduction with NaBH₄. The presence of acid-base and ox-red sites allows this 3.1% Ru/UiO-66 material acting as a bifunctional catalyst for the reduction of nitroarenes and tandem reaction of alcohol oxidation/Knoevenagel condensation. The high efficiency of 3.1% Ru/UiO-66 was demonstrated in the reduction of nitroarenes to amines. This system can be applied as a catalyst for at least six successive cycles without loss of activity. The 3.1% Ru/UiO-66 catalyst also was active in the tandem aerobic oxidation of alcohols/Knoevenagel condensation with malononitrile. However, the activity of this catalyst strongly decreased in the second cycle. A combination of physicochemical and catalytic experimental data indicated that Ru nanoparticles are the active sites both for the catalytic reduction of nitro compounds and the aerobic oxidation of alcohols. The activity for the Knoevenagel condensation reaction was from the existence of the "Zr ⁿ⁺-O^2- Lewis acid-base" pair in the framework of UiO-66.

One-Pot Combination of Metal- and Bio-Catalysis in Water for the Synthesis of Chiral Molecules

During the last decade, the combination of different metal- and bio-catalyzed organic reactions in aqueous media has permitted the flourishing of a variety of one-pot asymmetric multi-catalytic reactions devoted to the construction of enantiopure and high added-value chemicals under mild reaction conditions (usually room temperature) and in the presence of air. Herein, a comprehensive account of the state-of-the-art in the development of catalytic networks by combining metallic and biological catalysts in aqueous media (the natural environment of enzymes) is presented. Among others, the combination of metal-catalyzed isomerizations, cycloadditions, hydrations, olefin metathesis, oxidations, C-C cross-coupling and hydrogenation reactions, with several biocatalyzed transformations of organic groups (enzymatic reduction, epoxidation, halogenation or ester hydrolysis), are discussed.

Synthetically useful variants of industrial lipases from Burkholderia cepacia and Pseudomonas fluorescens

Industrial enzymes lipase PS (LPS) and lipase AK (LAK), which originate from Burkholderia cepacia and Pseudomonas fluorescens, respectively, are synthetically useful biocatalysts. To strengthen their catalytic performances, we introduced two mutations into hot spots of the active sites (residues 287 and 290). The LPS_L287F/I290A double mutant showed high catalytic activity and enantioselectivity for poor substrates for which the wild-type enzyme showed very low activity. The LAK_V287F/I290A double mutant was also an excellent biocatalyst with expanded substrate scope, which was comparable to the LPS_L287F/I290A double mutant. Thermodynamic parameters were determined to address the origin of the high enantioselectivity of the double mutant. The ΔΔH^‡ term, but not the ΔΔS^‡ term, was predominant, which suggests that the enantioselectivity is driven by a differential energy associated with intermolecular interactions around Phe287 and Ala290. A remarkable solvent effect was observed, giving a bell-shaped profile between the E values and the log P or ε values of solvents with the highest E value in i-Pr₂O. This suggests that an organic solvent with appropriate hydrophobicity and polarity provides the double mutant with some flexibility that is essential for excellent catalytic performance.

Hot off the press

A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as macrophilone A from Macrorhynchia philippina.