Screening of Biocatalysts for Synthesis of the Wieland–Miescher Ketone

Abstract

Lipases, a versatile class of biocatalysts, have been shown to function in non-aqueous media/organic solvents and to possess “promiscuous” catalytic activity for a wide range of organic transformations. In this study, we explored the biocatalytic properties of a library of commercially available lipases by screening them for catalysis of a one-pot synthesis of Wieland–Miescher ketone, an important intermediate in the synthesis of biologically active compounds such as steroids and terpenoids, from methyl vinyl ketone and 2-methyl-1,3-cyclohexanedione. As a direct outgrowth of this screen, we created an optimized procedure for Wieland–Miescher ketone (WMK) synthesis using crude lipase preparations, characterizing both reaction yield and enantiomeric excess. We also identified principal components of the crude lipase mixture through proteomics and present evidence for a non-lipolytic origin of the observed catalysis. Finally, using the optimized conditions developed in this study, we propose a general absorbance-based screening methodology for assessing biocatalytic potential of crude enzyme preparations for synthesis of WMK.