Enantioselective C–C bond synthesis catalysed by enzymes
ABSTRACT The enantioselective synthesis of C-C bonds is often the pivotal step of a synthesis. Nature has made a variety of versatile enzymes available that catalyse this type of reaction very selectively under mild conditions. Cyanohydrins, acyloins (alpha-hydroxy ketones), alpha-hydroxy acids and aldols (beta-hydroxy ketones) are very efficiently synthesised enantioselectively with the aid of C-C bond forming enzymes, which we discuss in this tutorial review. In the case of the alpha-hydroxy acids the applications of nitrilases in a synthetic dkr even allows a disconnection that has no enantioselective chemical equivalent.
- SourceAvailable from: Alexandre Barrozo
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- "Also, while most enzymes work within limited and tightly controlled temperature ranges, there do exist enzymes that can act anywhere within a temperature range from 0 to 100 °C (for the two extremes observed in extremophile bacteria) . On top of this, enzymes have chiral active sites, making them able to discriminate between different stereoisomers and regioisomers, with at times quite high efficiency, making them ideal catalysts for enantio- and regioselective chiral chemistry, in order to generate isomerically pure pharmaceuticals and fine chemicals [17,18]. "
ABSTRACT: Enzymes are tremendously proficient catalysts, which can be used as extracellular catalysts for a whole host of processes, from chemical synthesis to the generation of novel biofuels. For them to be more amenable to the needs of biotechnology, however, it is often necessary to be able to manipulate their physico-chemical properties in an efficient and streamlined manner, and, ideally, to be able to train them to catalyze completely new reactions. Recent years have seen an explosion of interest in different approaches to achieve this, both in the laboratory, and in silico. There remains, however, a gap between current approaches to computational enzyme design, which have primarily focused on the early stages of the design process, and laboratory evolution, which is an extremely powerful tool for enzyme redesign, but will always be limited by the vastness of sequence space combined with the low frequency for desirable mutations. This review discusses different approaches towards computational enzyme design and demonstrates how combining newly developed screening approaches that can rapidly predict potential mutation "hotspots" with approaches that can quantitatively and reliably dissect the catalytic step can bridge the gap that currently exists between computational enzyme design and laboratory evolution studies.International Journal of Molecular Sciences 12/2012; 13(10):12428-60. DOI:10.3390/ijms131012428 · 2.86 Impact Factor
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- "Their bifunctional nature (keto-and hydroxy group) and the presence of a stereocenter render them important as building blocks for several pharmaceuticals (Hilterhaus and Liese, 2007; Kara and Liese, 2010). The enzymes involved in the C–C bond formation between two carbonyl groups yielding 2- hydroxyketones rely mainly on the cofactor thiamine diphosphate (ThDP), a derivative of vitamin B 1 (Pohl et al., 2002; Jordan, 2003; Sukumaran and Hanefeld, 2005). Benzoylformate decarboxylase (BFD, EC 126.96.36.199) "
ABSTRACT: Benzoylformate decarboxylase (BFD, EC 188.8.131.52) is a homotetrameric thiamine diphosphate (ThDP)-dependent enzyme which catalyzes the synthesis of chiral 2-hydroxyketones accepting a broad range of aldehydes as substrates. In this study the synthesis of 2-hydroxypropiophenone (2-HPP) from benzaldehyde and acetaldehyde was catalyzed by three BFD variants namely BFD F464I, BFD A460I and BFD A460I-F464I. This paper reports the effect of hydrostatic pressure up to 290 MPa when the reactions were carried out at different benzaldehyde concentrations (5-40 mM) as well as at different pH values (7.0-8.5). Acetaldehyde concentration was fixed at 400 mM in all biotransformations. Reactions performed at high benzaldehyde concentrations and at high hydrostatic pressures showed an increase in (R)-2-HPP formation catalyzed by all BFD variants. For BFD A460I-F464I we observed an increase in the ee of (R)-2-HPP up to 80%, whereas at atmospheric conditions this variant synthesizes (R)-2-HPP with an ee of only 50%. Alkaline conditions (up to pH 8.5) and high hydrostatic pressures resulted in an increase of (R)-2-HPP synthesis, especially in the case of BFD A460I and BFD F464I.Journal of Biotechnology 02/2011; 152(3):87-92. DOI:10.1016/j.jbiotec.2011.01.020 · 2.87 Impact Factor
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- "Biocatalysis has developed into a powerful tool for organic synthesis due to its high efficiency, good selectivity and environmental acceptability (García-Urdiales et al., 2005; Reetz and Hauer, 2007; Sukumaran and Hanefeld, 2005). Although it is well known that a given enzyme is able to catalyze a specific reaction efficiently, some unexpected experimental results have indicated that many enzymes are catalytically promiscuous; i.e., they have the ability to catalyze distinctly different reactions (Copley, 2003; Khersonsky et al., 2006; Hult and Berglund, 2007). "
ABSTRACT: Several proteases, especially pepsin, were observed to directly catalyze asymmetric aldol reactions. Pepsin, which displays well-documented proteolytic activity under acidic conditions, exhibited distinct catalytic activity in a crossed aldol reaction between acetone and 4-nitrobenzaldehyde with high yield and moderate enantioselectivity. Fluorescence experiments indicated that under neutral pH conditions, pepsin maintains its native conformation and that the natural structure plays an important role in biocatalytic promiscuity. Moreover, no significant loss of enantioselectivity was found even after four cycles of catalyst recycling, showing the high stability of pepsin under the selected aqueous reaction conditions. This case of biocatalytic promiscuity not only expands the application of proteases to new chemical transformations, but also could be developed into a potentially valuable method for green organic synthesis.Journal of Biotechnology 10/2010; 150(4):539-45. DOI:10.1016/j.jbiotec.2010.10.004 · 2.87 Impact Factor