Linum usitatissimum Hydroxynitrile Lyase Cross-Linked Enzyme Aggregates: A Recyclable Enantioselective Catalyst

An immobilized form of the hydroxynitrile lyase from Linum usitatissimum (LuHNL) as crosslinked enzyme aggregate (CLEA) with high specific activity (303.5 U/g) and recovery (33%) was developed. Molecular imprinting using 2-butanone as additive in the immobilization process improved the synthetic activity of the biocatalyst. LuCLEA could be partially recycled for the synthesis of (R)-2-butanone cyanohydrin on a preparative scale over two batches. The enantioenriched cyanohydrin obtained was further hydrolyzed to give (R)-2-hydroxy-2-methylbutyric acid in 85% yield (from 2-butanone) and 87% ee.