title: Discovery of a novel (R)-selective bacterial hydroxynitrile lyase from Acidobacterium capsulatum.
abstract: Hydroxynitrile lyases (HNLs) are powerful carbon-carbon bond forming enzymes. The reverse of their natural reaction - the stereoselective addition of hydrogen cyanide (HCN) to carbonyls - yields chiral cyanohydrins, versatile building blocks for the pharmaceutical and chemical industry. Recently, bacterial HNLs have been discovered, which represent a completely new type: HNLs with a cupin fold. Due to various benefits of cupins (e.g. high yield recombinant expression in Escherichia coli), the class of cupin HNLs provides a new source for interesting, powerful hydroxynitrile lyases in the ongoing search for HNLs with improved activity, enantioselectivity, stability and substrate scope. In this study, database mining revealed a novel cupin HNL from Acidobacterium capsulatum ATCC 51196 (AcHNL), which was able to catalyse the (R)-selective synthesis of mandelonitrile with significantly better conversion (97%) and enantioselectivity (96.7%) than other cupin HNLs.
authors.affiliation: ACIB GmbH, Austrian Centre of Industrial Biotechnology, c/o TU Graz, Petersgasse 14/4, 8010 Graz, Austria.
authors.forename: Romana
authors.initials: R
authors.lastname: Wiedner
authors.affiliation: ACIB GmbH, Austrian Centre of Industrial Biotechnology, c/o TU Graz, Petersgasse 14/4, 8010 Graz, Austria.
authors.forename: Mandana
authors.initials: M
authors.lastname: Gruber-Khadjawi
authors.affiliation: ACIB GmbH, Austrian Centre of Industrial Biotechnology, c/o TU Graz, Petersgasse 14/4, 8010 Graz, Austria ; Institute of Molecular Biotechnology, TU Graz, Petersgasse 14/5, 8010 Graz, Austria.
authors.forename: Helmut
authors.initials: H
authors.lastname: Schwab
authors.affiliation: ACIB GmbH, Austrian Centre of Industrial Biotechnology, c/o TU Graz, Petersgasse 14/4, 8010 Graz, Austria.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Steiner
keywords: Biocatalysis; Cyanohydrin synthesis; Hydroxynitrile lyase; Mandelonitrile; Manganese-dependent HNL