Synthesis and analysis of a fluorinated product analogue as an inhibitor for 1-deoxy-d-xylulose 5-phosphate reductoisomerase

1-Deoxy-d-xylulose 5-phosphate (DXP) reductoisomerase (DXR) is an NADPH-dependent enzyme catalyzing the rearrangement and reduction of DXP to methyl-d-erythritol 4-phosphate (MEP). Two mechanisms for this enzymatic reaction have been proposed, involving either an α-ketol rearrangement or a retroaldol/aldol rearrangement. In this study, a fluorinated product analogue, FCH2-MEP, was synthesized as a possible mechanism-based inactivator for DXR if the retroaldol/aldol mechanism is operative. FCH2-MEP was found to be a weak competitive inhibitor, and thus was unable to discriminate between the mechanisms. This result is due to the inability of the targeted enzyme, DXR, to oxidize FCH2-MEP to the aldehyde intermediate that is common to both mechanisms. While FCH2-MEP failed to act as a mechanism-based inactivator, the insight gained from this study will assist in the future design of inhibitors of DXR.