Search

Production of commodity chemicals, such as benzene, toluene, ethylbenzene, and xylenes (BTEX), from renewable resources is key for a sustainable society. Biocatalysis enables one‐pot multistep transformation of bioresources under mild conditions, yet it is often limited to biochemicals. Herein, we developed a non‐natural three‐enzyme cascade for one‐pot conversion of biobased l‐phenylalanine into ethylbenzene. The key rate‐limiting photodecarboxylase was subjected to structure‐guided semirational engineering, and a triple mutant CvFAP(Y466T/P460A/G462I) was obtained with a 6.3‐fold higher productivity. With this improved photodecarboxylase, an optimized two‐cell sequential process was developed to convert l‐phenylalanine into ethylbenzene with 82 % conversion. The cascade reaction was integrated with fermentation to achieve the one‐pot bioproduction of ethylbenzene from biobased glycerol, demonstrating the potential of cascade biocatalysis plus enzyme engineering for the production of biobased commodity chemicals. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biocatalytic alkylations are important reactions to obtain chemo‐, regio‐ and stereoselectively alkylated compounds. This can be achieved using S‐adenosyl‐l‐methionine (SAM)‐dependent methyltransferases and SAM analogs. It was recently shown that a halide methyltransferase (HMT) from Chloracidobacterium thermophilum can synthesize SAM from SAH and methyl iodide. We developed an iodide‐based assay for the directed evolution of an HMT from Arabidopsis thaliana and used it to identify a V140T variant that can also accept ethyl‐, propyl‐, and allyl iodide to produce the corresponding SAM analogs (90, 50, and 70 % conversion of 15 mg SAH). The V140T AtHMT was used in one‐pot cascades with O‐methyltransferases (IeOMT or COMT) to achieve the regioselective ethylation of luteolin and allylation of 3,4‐dihydroxybenzaldehyde. While a cascade for the propylation of 3,4‐dihydroxybenzaldehyde gave low conversion, the propyl‐SAH intermediate could be confirmed by NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We engineered the cytochrome P450 monooxygenase CYP107D1 (OleP) from Streptomyces antibioticus for the stereo‐ and regioselective 7β‐hydroxylation of lithocholic acid (LCA) to yield ursodeoxycholic acid (UDCA). OleP was previously shown to hydroxylate testosterone at the 7β‐position but LCA is exclusively hydroxylated at the 6β‐position, forming murideoxycholic acid (MDCA). Structural and 3DM analysis, and molecular docking were used to identify amino acid residues F84, S240, and V291 as specificity‐determining residues. Alanine scanning identified S240A as a UDCA‐producing variant. A synthetic "small but smart" library based on these positions was screened using a colorimetric assay for UDCA. We identified a nearly perfectly regio‐ and stereoselective triple mutant (F84Q/S240A/V291G) that produces 10‐fold higher levels of UDCA than the S240A variant. This biocatalyst opens up new possibilities for the environmentally friendly synthesis of UDCA from the biological waste product LCA. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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. [ABSTRACT FROM AUTHOR]

2‐Phenylethanol (2‐PE) is an aroma compound with a rose‐like odors widely used as food ingredient, and natural 2‐PE is much preferred for the application with high selling price but limited availability. Bioproduction of 2‐PE from bioresources could provide a green, sustainable, and economic process to manufacture natural 2‐PE. Here we report a novel artificial cascade biotransformation to convert bioderived L‐phenylalanine (L‐Phe) to natural 2‐PE via deamination, decarboxylation, epoxidation, isomerization, and reduction in one pot. Recombinant E. coli strains co‐expressing the 5 necessary enzymes were engineered by using double plasmids, modular approach, and random combination as highly active, easily available, and recyclable biocatalysts. Two‐phase biotransformation with E. coli (RE) cells using biodiesel, a green and easily available solvent for in situ product extraction to minimize the inhibition, significantly improved product concentration and yield, converting 80 mM of L‐Phe to 71 mM (8.8 g/L, 89 % yield) of 2‐PE. The inhibition of 2‐PE was also reduced through in‐situ product adsorption using XAD4 resins. Using XAD4‐biodiesel‐aqueous buffer 3‐phase system could further enhance the concentration of 2‐PE to 85 mM (10.4 g/L, 85 % yield). The developed artificial cascade biotransformation of L‐Phe to 2‐PE is much better than other reported bioproductions of 2‐PE and provides high‐yielding, sustainable, and potentially practical synthesis of high‐value natural 2‐PE. Getting out while the going is good: A novel and high‐yielding cascade biotransformation for the synthesis of natural 2‐PE from biobased L‐Phe via artificial pathway was developed. Recombinant E. coli strains coexpressing 5 necessary enzymes were engineered for the designed cascades by a modular approach. The biocatalytic performance was significantly improved by applying in‐situ product removal system, giving 2‐PE in high concentration and high yield. [ABSTRACT FROM AUTHOR]

Alkenes are excellent starting materials for organic synthesis due to the versatile reactivity of C=C bonds and the easy availability of many unfunctionalised alkenes. Direct regio- and/or enantioselective conversion of alkenes into functionalised (chiral) compounds has enormous potential for industrial applications, and thus has attracted the attention of researchers for extensive development using chemo-catalysis over the past few years. On the other hand, many enzymes have also been employed for conversion of alkenes in a highly selective and much greener manner to offer valuable products. Herein, we review recent advances in seven well-known types of biocatalytic conversion of alkenes. Remarkably, recent mechanism-guided directed evolution and enzyme cascades have enabled the development of seven novel types of single-step and one-pot multi-step functionalisation of alkenes, some of which are even unattainable via chemo-catalysis. These new reactions are particularly highlighted in this feature article. Overall, we present an ever-expanding enzyme toolbox for various alkene functionalisations inspiring further research in this fast-developing theme. [ABSTRACT FROM AUTHOR]

Green and selective oxidation methods are highly desired in chemical synthesis and manufacturing. In this work, we have developed a biocatalytic method for the regio- and stereoselective oxidation of styrene derivatives into arylacetic and ( S)-2-arylpropionic acids via a one-pot epoxidation-isomerization-oxidation sequence. This was done via the engineering of Escherichia coli (StyABC-EcALDH) coexpressing styrene monooxygenase (SMO), styrene oxide isomerase (SOI) and aldehyde dehydrogenase (EcALDH) as an active and easily available whole-cell catalyst. Regioselective oxidation of styrene and 11 substituted styrenes using the E. coli cells was performed in a one-pot set-up, producing 12 phenylacetic acids in both high conversion and high yield. Engineering of E. coli (StyABC-ADH9v1) coexpressing SMO, SOI and ADH9v1 (a mutated alcohol dehydrogenase) led to biocatalysts capable of regio- and stereoselective oxidation of α-methylstyrene derivatives to the corresponding chiral acids. One-pot asymmetric synthesis of 4 ( S)-2-arylpropionic acids was achieved in good conversion and excellent ee with the E. coli cells. This is a new type of asymmetric alkene oxidation to give chiral acids with no chemical counterpart thus far. The cascade bio-oxidation operates under mild conditions, uses molecular oxygen, exhibits very high regio- and enantioselectivity, and gives high conversion, thus providing a green and efficient method for the synthesis of arylacetic acids and ( S)-2-arylpropionic acids directly from easily available styrenes. [ABSTRACT FROM AUTHOR]