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 alpha-ketol rearrangement or a retroaldol/aldol rearrangement. In this study, a fluorinated product analogue, FCH(2)-MEP, was synthesized as a possible mechanism-based inactivator for DXR if the retroaldol/aldol mechanism is operative. FCH(2)-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 FCH(2)-MEP to the aldehyde intermediate that is common to both mechanisms. While FCH(2)-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.
Aldose-Ketose Isomerases Enzyme Inhibitors