Incorporation of [I-¹⁴C]-Isopentenyl Pyrophosphate into Polyisoprene

Abstract

THE occurrence of 3-methyl-but-3-enyl-1-pyrophos phate (isopentenyl pyrophosphate) as an intermediate in the enzymic synthesis of squalene from mevalonic acid, using yeast extracts, has been demonstrated by Bloch et al. ^1,2, and by Lynen et al. ³. The latter authors also quote an unpublished report by Arreguin that isopentenyl pyrophosphate can be incorporated into the rubber of Taraxacum kok-saghyz latex. The in vitro conversion of mevalonic acid lactone into polyisoprene in the presence of natural rubber (Hevea brasiliensis) latex has been shown by Park and Bonner⁴ and by Kekwick et al. ⁵. In the experiments reported here it is demonstrated that isopentenyl pyrophosphate, on incubation with fresh Hevea brasiliensis latex, is rapidly converted into high molecular weight polyisoprene with essentially 100 per cent efficiency.