Catalytic Scope of the Thiamine‐Dependent Multifunctional Enzyme Cyclohexane‐1,2‐dione Hydrolase |
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| Authors: | Sabrina Loschonsky Simon Waltzer Dr Sonja Fraas Tobias Wacker Prof Dr Susana L A Andrade Prof Dr Peter M H Kroneck Prof Dr Michael Müller |
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| Affiliation: | 1. Institut für Pharmazeutische Wissenschaften, Albert‐Ludwigs‐Universit?t Freiburg, Albertstrasse 25, 79104 Freiburg (Germany);2. Institut für Biologie, Universit?t Konstanz, Universit?tsstrasse 10, 78464 Konstanz (Germany);3. Institut für Biochemie and BIOSS Center for Biological Signalling Studies, Albert‐Ludwigs‐Universit?t Freiburg, Albertstrasse 21, 79104 Freiburg (Germany) |
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| Abstract: | The thiamine diphosphate (ThDP)‐dependent enzyme cyclohexane‐1,2‐dione hydrolase (CDH) was expressed in Escherichia coli and purified by affinity chromatography (Ni‐NTA). Recombinant CDH showed the same C?C bond‐cleavage and C?C bond‐formation activities as the native enzyme. Furthermore, we have shown that CDH catalyzes the asymmetric cross‐benzoin reaction of aromatic aldehydes and (decarboxylated) pyruvate (up to quantitative conversion, 92–99 % ee). CDH accepts also hydroxybenzaldehydes and nitrobenzaldehydes; these previously have not (or only in rare cases) been known as substrates of other ThDP‐dependent enzymes. On a semipreparative scale, sterically demanding 4‐(tert‐butyl)benzaldehyde and 2‐naphthaldehyde were transformed into the corresponding 2‐hydroxy ketone products in high yields. Additionally, certain benzaldehydes with electron withdrawing substituents were identified as potential inhibitors of the ligase activity of CDH. |
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| Keywords: | asymmetric catalysis C C bond‐formation carboligation enzyme catalysis ThDP |
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