Process development for enzyme catalysed asymmetric C–C-bond formation

Kühl, Sven; Zehentgruber, Daniela; Pohl, Martina; Müller, Michael; Lütz, Stephan

doi:10.1016/j.ces.2007.02.029

Cited by 16 publications

(6 citation statements)

References 6 publications

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“…Finally, it should be emphasized that the above‐mentioned asymmetric transformations can be applied under appropriate conditions on a technical scale [59], either in a batch or continuous mode [60,61]. This, of course, is also true for other ThDP‐dependent enzymes like TK [62].…”

Section: Substrate and Reaction Engineeringmentioning

confidence: 99%

Thiamin diphosphate in biological chemistry: exploitation of diverse thiamin diphosphate‐dependent enzymes for asymmetric chemoenzymatic synthesis

2009

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Thiamin diphosphate-dependent enzymes participate in numerous biosynthetic pathways and catalyse a broad range of reactions, mainly involving the cleavage and formation of C-C bonds. For example, they catalyse the nonoxidative and oxidative decarboxylation of 2-keto acids, produce 2-hydroxy ketones and transfer activated aldehydes to a variety of acceptors. Moreover, they can also catalyse C-N, C-O and C-S bond formation. Because of their substrate spectra and different stereospecificity, these enzymes extend the synthetic potential for asymmetric carboligations appreciably. Different strategies have been developed to identify new members of this promiscuous enzyme class and the reactions they catalyse. This enabled us to introduce solutions for longstanding synthetic problems, such as asymmetric cross-benzoin condensation. Moreover, through a combination of protein structure analysis, enzyme and substrate engineering, and screening methods we explored additional stereochemical routes that have not been described previously for any of these interesting enzymes.

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Section: Substrate and Reaction Engineeringmentioning

confidence: 99%

Thiamin diphosphate in biological chemistry: exploitation of diverse thiamin diphosphate‐dependent enzymes for asymmetric chemoenzymatic synthesis

2009

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“…Here, the potential to catalyse the formation of mixed carboligation products from a donor substrate and an acceptor substrate in a highly chemoselective and stereoselective manner is of special interest. Among the enzymes that have been most intensively studied are transketolase (TK) from Escherichia coli and Saccharomyces cerevisiae , acetohydroxy acid synthase (AHAS) isoenzymes I–III from E. coli , benzoylformate decarboxylase (BFD) from Pseudomonas putida , benzaldehyde lyase (BAL) from Pseudomonas fluorescens , pyruvate decarboxylase (PDC) from S. cerevisiae , Zymomonas mobilis and Acetobacter pasteurianus , branched chain ketoacid decarboxylase from Lactococcus lactis , cyclohexane‐1,2‐dione hydrolase from Azoarcus sp. and 2‐succinyl‐5‐enolpyruvyl‐6‐hydroxy‐3‐cyclohexene‐1‐carboxylate (SEPHCHC) synthase (MenD) from E. coli .…”

Section: Introductionmentioning

confidence: 99%

Engineering stereoselectivity of ThDP-dependent enzymes

Hailes

Rother

Müller

et al. 2013

FEBS J

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Thiamine diphosphate-dependent enzymes are broadly distributed in all organisms, and they catalyse a broad range of C-C bond forming and breaking reactions. Enzymes belonging to the structural families of decarboxylases and transketolases have been particularly well investigated concerning their substrate range, mechanism of stereoselective carboligation and carbolyase reaction. Both structurally different enzyme families differ also in stereoselectivity: enzymes from the decarboxylase family are predominantly R-selective, whereas those from the transketolase family are S-selective. In recent years a key focus of our studies has been on stereoselective benzoin condensation-like 1,2-additions. Meanwhile, several S-selective variants of pyruvate decarboxylase, benzoylformate decarboxylase and 2-succinyl-5-enolpyruvyl-6-hydroxy-3-cyclohexene-1-carboxylate (SEPH-CHC) synthase as well as R-selective transketolase variants were created that allow access to a broad range of enantiocomplementary a-hydroxyketones and a,a′-dihydroxyketones. This review covers recent studies and the mechanistic understanding of stereoselective C-C bond forming thiamine diphosphate-dependent enzymes, which has been guided by structure-function analyses based on mutagenesis studies and from influences of different substrates and organic co-solvents on stereoselectivity.

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“…In recent years, we have created a toolbox of ThDP-dependent enzymes including wild-type and engineered enzymes with varying selectivities to access a broad range of predominantly mixed aromatic and aliphatic chiral 2-hydroxy ketones 2f,4. In doing so, different organic cosolvents [e.g., dimethyl sulfoxide (DMSO),5 methyl tert -butyl ether (MTBE),6 2-methyltetrahydrofuran (MTHF)7] were used in order to increase the solubility of the aromatic compounds in the aqueous reaction system. Depending on the enzyme and the reaction studied, the influence of the organic cosolvents ranged between no effect relative to the aqueous system to significant influence on enzyme activity, stability and selectivity.…”

Section: Introductionmentioning

confidence: 99%

Influence of Organic Solvents on Enzymatic Asymmetric Carboligations

et al. 2012

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The asymmetric mixed carboligation of aldehydes with thiamine diphosphate (ThDP)-dependent enzymes is an excellent example where activity as well as changes in chemo- and stereoselectivity can be followed sensitively. To elucidate the influence of organic additives in enzymatic carboligation reactions of mixed 2-hydroxy ketones, we present a comparative study of six ThDP-dependent enzymes in 13 water-miscible organic solvents under equivalent reaction conditions. The influence of the additives on the stereoselectivity is most pronounced and follows a general trend. If the enzyme stereoselectivity in aqueous buffer is already >99.9% ee, none of the solvents reduces this high selectivity. In contrast, both stereoselectivity and chemoselectivity are strongly influenced if the enzyme is rather unselective in aqueous buffer. For the S-selective enzyme with the largest active site, we were able to prove a general correlation of the solvent-excluded volume of the additives with the effect on selectivity changes: the smaller the organic solvent molecule, the higher the impact of this additive. Further, a correlation to log P of the additives on selectivity was detected if two additives have almost the same solvent-excluded volume. The observed results are discussed in terms of structural, biochemical and energetic effects. This work demonstrates the potential of medium engineering as a powerful additional tool for varying enzyme selectivity and thus engineering the product range of biotransformations. It further demonstrates that the use of cosolvents should be carefully planned, as the solvents may compete with the substrate(s) for binding sites in the enzyme active site.

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Process development for enzyme catalysed asymmetric C–C-bond formation

Cited by 16 publications

References 6 publications

Thiamin diphosphate in biological chemistry: exploitation of diverse thiamin diphosphate‐dependent enzymes for asymmetric chemoenzymatic synthesis

Thiamin diphosphate in biological chemistry: exploitation of diverse thiamin diphosphate‐dependent enzymes for asymmetric chemoenzymatic synthesis

Engineering stereoselectivity of ThDP-dependent enzymes

Influence of Organic Solvents on Enzymatic Asymmetric Carboligations

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