Rubber formation by fresh bottom fraction of Hevea latex

Abstract

The formation de novo of rubber was confirmed by the incorporation of14C-IDP into rubber by fresh bottom fraction (BF) and C-serum (CS) at 37°for 6 hr after pre-incubation with the substrate at 4 overnight. The incorporation of14C-IDP and rubber yield were highest in fresh BF, A control experiment with boiled BF showed practically no incorporation of14C-IDP, although it contained about 1% (w/w dried BF) of rubber corresponding to pre-existing rubber. A very small amount of rubber was formed on incubation of CS and14C-IDP. Rubber formation in fresh Bf was inhibited by the addition of NaF. Freeze-dried BF formed no rubber, although it was able to form polyprenols. The radiolabelled rubber formed on incubation of fresh Bf and14C-IDP showed a molecular-weight distribution (MWD) having a peak similar to the low molecular-weight fraction of the skewed unimodal distribution of the endogenous rubber. Membrane-bound particles in fresh BF are presumed to have an important role in the synthesis of new rubber molecules.