In vitro enzymatic oxidation of a fluorine-tagged sulfido substrate analogue: A¹⁹F NMR investigation

¹H-decoupled ¹⁹F NMR has been used to monitor the highly regioselective oxidation of a fluorine-tagged thia-fatty acid derivative by castor stearoyl-ACP Δ⁹ desaturase. The major enzymatic product, after reductive work-up, was identified as 9-fluoro-1-nonanol. This compound could be easily distinguished from substrate and a 9-sulfoxy by-product on the basis of its ¹⁹F NMR chemical shift and spiking experiments using authentic standards. Structural assignment of the cleavage product was confirmed by GC-MS analysis of the enzymatic products.