title: Catalytic scope of the thiamine-dependent multifunctional enzyme cyclohexane-1,2-dione hydrolase.
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.
authors.affiliation: Institut für Pharmazeutische Wissenschaften, Albert-Ludwigs-Universität Freiburg, Albertstrasse 25, 79104 Freiburg (Germany).
authors.forename: Sabrina
authors.initials: S
authors.lastname: Loschonsky
authors.forename: Simon
authors.initials: S
authors.lastname: Waltzer
authors.forename: Sonja
authors.initials: S
authors.lastname: Fraas
authors.forename: Tobias
authors.initials: T
authors.lastname: Wacker
authors.forename: Susana L A
authors.initials: SL
authors.lastname: Andrade
authors.forename: Peter M H
authors.initials: PM
authors.lastname: Kroneck
authors.forename: Michael
authors.initials: M
authors.lastname: Müller
mesh_terms: D020627:Azoarcus / Q000201:enzymology; D001547:Benzaldehydes / Q000737:chemistry / Q000378:metabolism; D001573:Benzoin / Q000737:chemistry / Q000378:metabolism; D055162:Biocatalysis; D064251:Multifunctional Enzymes / Q000235:genetics / Q000378:metabolism*; D019289:Pyruvic Acid / Q000737:chemistry / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification; D013831:Thiamine / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001547:Benzaldehydes; D064251:Multifunctional Enzymes; D011994:Recombinant Proteins; D019289:Pyruvic Acid; D001573:Benzoin; C032175:benzaldehyde; D013831:Thiamine
keywords: CC bond-formation; ThDP; asymmetric catalysis; carboligation; enzyme catalysis