Extended Reaction Scope of Thiamine Diphosphate Dependent Cyclohexane‐1,2‐dione Hydrolase: From CC Bond Cleavage to CC Bond Ligation |
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| Authors: | Dipl.‐Chem. Sabrina Loschonsky Dipl.‐Chem. Tobias Wacker Simon Waltzer Dr. Pier Paolo Giovannini Prof. Dr. Michael J. McLeish Prof. Dr. Susana L. A. Andrade Prof. Dr. Michael Müller |
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| Affiliation: | 1. Institute of Pharmaceutical Sciences, Albert‐Ludwigs‐Universit?t Freiburg, Albertstrasse 25, 79104 Freiburg (Germany);2. Institute for Biochemistry and BIOSS Center for Biological Signalling Studies, Albert‐Ludwigs‐Universit?t Freiburg, Albertstrasse 21, 79104 Freiburg (Germany);3. Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Ferrara, Via L. Borsari, 46, 44121 Ferrara (Italy);4. Department of Chemistry and Chemical Biology, Indiana University‐Purdue University Indianapolis, 402 N. Blackford St., Indianapolis, IN 46202 (USA) |
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| Abstract: | ThDP‐dependent cyclohexane‐1,2‐dione hydrolase (CDH) catalyzes the C? C bond cleavage of cyclohexane‐1,2‐dione to 6‐oxohexanoate, and the asymmetric benzoin condensation between benzaldehyde and pyruvate. One of the two reactivities of CDH was selectively knocked down by mutation experiments. CDH‐H28A is much less able to catalyze the C? C bond formation, while the ability for C? C bond cleavage is still intact. The double variant CDH‐H28A/N484A shows the opposite behavior and catalyzes the addition of pyruvate to cyclohexane‐1,2‐dione, resulting in the formation of a tertiary alcohol. Several acyloins of tertiary alcohols are formed with 54–94 % enantiomeric excess. In addition to pyruvate, methyl pyruvate and butane‐2,3‐dione are alternative donor substrates for C? C bond formation. Thus, the very rare aldehyde–ketone cross‐benzoin reaction has been solved by design of an enzyme variant. |
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| Keywords: | asymmetric synthesis benzoin condensation enzyme catalysis protein engineering tertiary alcohols |
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