Discovery of a novel (R)-selective bacterial hydroxynitrile lyase from Acidobacterium capsulatum

• Main Authors: Romana Wiedner, Mandana Gruber-Khadjawi, Helmut Schwab, Kerstin Steiner
• Format: Article
• Language: English
• Published: Elsevier 2014-06-01
• Series: Computational and Structural Biotechnology Journal
• Subjects: Hydroxynitrile lyase; Manganese-dependent HNL; Biocatalysis; Cyanohydrin synthesis; Mandelonitrile
• Online Access: http://www.sciencedirect.com/science/article/pii/S2001037014000117

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.