Illustration from Scientific Research

Catalysis is uniform in this class of enzymes and starts with a prenyl substrate (DMAPP or GPP) bound to the allylic site (Al). A trinuclear, divalent metal cluster surrounds the pyrophosphate moiety (PP Al ) and facilitates ionization of the ester bond (I). Basic residues of the homoallylic site (HAl) bind IPP, which attacks the nascent carbocation at C 1 of the prenyl moiety (II). The generated inorganic pyrophosphate (PP i ) deprotonates at C 2 (III) of the intermediate and restores the allylic character of the elongated metabolite (GPP or FPP).

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