It is interesting to note that the N-terminal half of geosmin synthase contains a second NSE magnesium-binding motif, approximately 38 residues downstream of the first [REF].
The first step in the mechanism is for FPP's carbon-carbon double bond farthest from the diphosphate group to attack the carbon adjacent to the diphosphate, forming a cyclic carbocation with the loss of the diphosphate group [REF].