Famesyl diphosphate sesquiterpene precursor

Figure 10.7 All terpenes are derived from allylic diphosphates which are polymers of repeating isopentyl units (IPP) put together by the action of prenyltransferases. In plants, IPP can be derived from the mevalonate biosynthetic pathway (a cytoplasmic pathway) or the methyl erythritol phosphate pathway (a plastidic pathway). Monoterpenes are then derived from the CIO precursor geranyl diphosphate (GPP), sesquiterpenes from the C15 precursor famesyl diphosphate (FPP), and diterpenes from the C20 precursor geranylgeranyl diphosphate (GGPP) by the action of terpene synthases or cyclases, which divert carbon into the specific branch pathways.

Modification of enzymes involved in the synthesis from universal precursors of other secondary metabolites has also been demonstrated. The sesquiterpene synthases are a large family of enzymes that act by a common mechanism and catalyze the cyclization of famesyl diphosphate, each to form a distinct sesquiterpene. The active site of the synthase that produces trichodiene, the... 

Fig. 1.4 Outline of terpenoid biosynthesis from isopentenyl diphosphate (IPP) via dimethylallyl diphosphate (DMAPP), gcranyl diphosphate (GPP), famesyl diphosphate (FPP) and geranylgcranyl diphosphate (GGPP). These reactions are catalyzed by isoprenyl diphosphate synthases and terpene synthases. The major products of the monoterpene, sesquiterpene, and diterpene pathways that constitute the oleoresm of Picea abies are listed. The general precursor IPP is derived either from the plastidial methylerythritol phosphate (MEP) pathway or the cytosolic mevalonaic pathway.

Sesquiterpenes are a major class of terpenes consisting of three isoprene units, providing the formula of to then-molecular structures (Fig. 7.1) [1]. Like all terpenes, their carbon skeletons are derived from the sequential addition of the active isoprene unit isopentenyl diphosphate (IDP or IPP) to other active diphosphates. In the case of sesquiterpenes, addition of a further IDP unit to geranyl diphosphate (GDP or GPP) (the essential precursor of all monoterpenes, please see Chapter 6) provides the fundamental sesquiterpene precursor famesyl diphosphate (FDP or FPP). 

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