Biocatalysis has found numerous applications in various fields as an alternative to chemical catalysis. The use of enzymes in organic synthesis, especially to make chiral compounds for pharmaceuticals as well for the flavors and fragrance industry, are the most prominent examples. In addition, biocatalysts are used on a large scale to make specialty and even bulk chemicals. This review intends to give illustrative examples in this field with a special focus on scalable chemical production using enzymes. It also discusses the opportunities and limitations of enzymatic syntheses using distinct examples and provides an outlook on emerging enzyme classes.

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Biocatalysis: Enzymatic Synthesis for Industrial Applications

Superabsorbent hydrogels based on polysaccharides for application in agriculture as soil conditioner and nutrient carrier: A review

Biopolymer aerogels were among the first aerogels produced, but only in the last decade has research on biopolymer and biopolymer-composite aerogels become popular, motivated by sustainability arguments, their unique and tunable properties, and ease of functionalization. Biopolymer aerogels and open-cell foams have great potential for classical aerogel applications such as thermal insulation, as well as emerging applications in filtration, oil-water separation, CO2 capture, catalysis, and medicine. The biopolymer aerogel field today is driven forward by empirical materials discovery at the laboratory scale, but requires a firmer theoretical basis and pilot studies to close the gap to market. This Review includes a database with over 3800 biopolymer aerogel properties, evaluates the state of the biopolymer aerogel field, and critically discusses the scientific, technological, and commercial barriers to the commercialization of these exciting materials.

Biopolymer Aerogels and Foams: Chemistry, Properties, and Applications.

The efficiency, selectivity and sustainability benefits offered by enzymes are enticing chemists to consider biocatalytic transformations to complement or even supplant more traditional synthetic routes. Increasing demands for efficient and versatile synthetic methods, combined with powerful new discovery and engineering tools, has prompted innovations in biocatalysis, especially the development of new enzymes for precise transformations or ‘molecular editing’. As a result, the past decade has witnessed an impressive expansion of the catalytic repertoire of enzymes to include new and useful transformations not known (or relevant) in the biological world. In this Review we illustrate various ways in which researchers have approached using the catalytic machineries of enzymes for new-to-nature transformations. These efforts have identified genetically encoded catalysts that can be tuned and diversified by engineering the protein sequence, particularly by directed evolution. Discovery and improvement of these new enzyme activities is opening a floodgate that connects the chemistry of the biological world to that invented by humans over the past 100 years. Advances in enzyme performance and capabilities are making them increasingly attractive to synthetic chemists. In this Review Chen and Arnold outline the ways that enzymes have been engineered to achieve reactivities well beyond their original functions.

Engineering new catalytic activities in enzymes

Oxidation chemistry using enzymes is approaching maturity and practical applicability in organic synthesis. Oxidoreductases (enzymes catalysing redox reactions) enable chemists to perform highly selective and efficient transformations ranging from simple alcohol oxidations to stereoselective halogenations of non-activated C-H bonds. For many of these reactions, no "classical" chemical counterpart is known. Hence oxidoreductases open up shorter synthesis routes based on a more direct access to the target products. The generally very mild reaction conditions may also reduce the environmental impact of biocatalytic reactions compared to classical counterparts. In this Review, we critically summarise the most important recent developments in the field of biocatalytic oxidation chemistry and identify the most pressing bottlenecks as well as promising solutions.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/anie.201800343

Biocatalytic Oxidation Reactions: A Chemist's Perspective

Peroxygenases offer attractive means to address challenges in selective oxyfunctionalisation chemistry. Despite their attractiveness, the application of peroxygenases in synthetic chemistry remains challenging due to their facile inactivation by the stoichiometric oxidant (H2O2). Often atom inefficient peroxide generation systems are required, which show little potential for large scale implementation. Here we show that visible light-driven, catalytic water oxidation can be used for in situ generation of H2O2 from water, rendering the peroxygenase catalytically active. In this way the stereoselective oxyfunctionalisation of hydrocarbons can be achieved by simply using the catalytic system, water and visible light.

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Selective aerobic oxidation reactions using a combination of photocatalytic water oxidation and enzymatic oxyfunctionalizations

The photoenzymatic decarboxylation of fatty acids to alkanes is proposed as an alternative approach for the synthesis of biodiesel. By using a recently discovered photodecarboxylase from Chlorella variabilis NC64A (CvFAP) we demonstrate the irreversible preparation of alkanes from fatty acids and triglycerides. Several fatty acids and their triglycerides are converted by CvFAP in near-quantitative yield and exclusive selectivity upon illumination with blue light. Very promising turnover numbers of up to 8000 were achieved in this proof-of-concept study.

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Light-Driven Enzymatic Decarboxylation of Fatty Acids.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/ange.201800343

Biokatalytische Oxidationsreaktionen - aus der Sicht eines Chemikers

Selective oxyfunctionalisation of inert C-H bonds under mild conditions can be achieved using peroxygenases. This approach, however, is impaired by the poor robustness of these enzymes in the presence of hydrogen peroxide as the stoichiometric oxidant. Here, we demonstrate that inorganic photocatalysts such as gold-titanium dioxide efficiently provide H2O2 from methanol-driven reductive activation of ambient oxygen in suitable amounts to ensure high reactivity and robustness of the enzyme. Using this approach stereoselective hydroxylation of ethyl benzene to (R)-1-phenyl ethanol in high enantioselectivity (>98% ee) and excellent turnover numbers of the biocatalyst (>71.000) was achieved.

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Wuyuan Zhang

Papers

Biocatalytic Oxidation Reactions: A Chemist's Perspective

Selective aerobic oxidation reactions using a combination of photocatalytic water oxidation and enzymatic oxyfunctionalizations

Light-Driven Enzymatic Decarboxylation of Fatty Acids.

Biokatalytische Oxidationsreaktionen - aus der Sicht eines Chemikers

Selective Activation of C-H Bonds in a Cascade Process Combining Photochemistry and Biocatalysis.