Isopentyl pyrophosphate biosynthesis

In pepper as in many plants, there are two sources of isoprene monomers the mevalonic acid pathway and the plastidal pool from pymvate and glyceraldehyde-3-phosphate [26], Pepper carotenoid biosynthesis uses the plastidal pathway for the isopentyl pyrophosphate monomers and the resident terpenoid synthases and transferases [27], Using the 5-carbon isoprene pool, the prenyl transferases sequentially... 

The biosynthesis of geranyl pyrophosphate is achieved in just three steps. The first step involves loss of a leaving group (pyrophosphate) to generate a resonance-stabilized carbocation. The second step is a nucleophilic attack in which the carbocation is attacked by the tt bond of isopentyl pyrophosphate to generate a new carbocation. Finally, a proton transfer yields geranyl pyrophosphate. 

The preceding discussion has indicated the sequence of squalene 4.8) biosynthesis as mevalonate 4.13) isopentyl pyrophosphate 4.14) dimethylallyl pyrophosphate 4.15) geranyl pyrophosphate 4.41) farnesyl pyrophosphate 4.19) squalene 4.8). Each stage involves stereochemical change at one or two carbon atoms. The presence of several prochiral centres in the molecules of this sequence meant that for stereochemical changes to be monitored they had to be chirally labelled with deuterium or tritium e.g. the condensation of isopentenyl pyrophosphate 4.14) with dimethylallyl pyrophosphate 4.15) (see Scheme 4.10) involves loss of one of the... 

The mechanics of latex formation in the rubber tree has been the subject of considerable study. It is now known that the monomer isopentyl pyrophosphate is the one used in the biosynthesis of natural rubber. Catalysts for these transformation are enzymes in the latex and tissues of Hevea. The structure for natural-rubber is c/5 -l,4-polyisoprene (1) and the trans form for the structure of gutta... 

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