New aspects of rubber biosynthesis

Abstract

New aspects of rubber biosynthesis. Following a review of the site of rubber biosynthesis in Hevea brasiliensis and Parthenium argentalum, evidence is given for the initiation of polyisoprene molecules from (ranMerpenoid precursors including geranylgeranyl pyrophosphate. All franj‐14C‐geranylgeraniol has been isolated from incubations of H. brasiliensis latex serum with 14C‐isopentenyl pyrophosphate. Gel‐filtration chromatography of the serum yields very small rubber particles of high biosynthetic activity, and two proteinaceous fractions. One of these increases the biosynthesis of rubber and may contain the enzyme, isopentenyldiphosphate δ‐isomerase, whilst the other appears to inhibit rubber formation. The nature and molecular weight of the rubber formed in vitro is discussed and a mechanism for the de novo formation of rubber particles is suggested. Copyright © 1987, Wiley Blackwell. All rights reserved