Natural rubber, obtained from Hevea brasiliensis, consists of ω’-terminal, two trans-1,4-isoprene units, long sequence of cis-1,4-isoprene units and α’-terminal (ω’-(trans)2-(cis)n-α’), in this order, in which the ω’ and α’ terminals represent unknown terminal groups attracted with proteins and phospholipids. The ω’ and α’ terminals are analyzed in relation to structures of polyprenols such as (CH3)2C=CHCH2-(trans)2-(cis)n-OH and (CH3)2C=CHCH2-(trans)3-(cis)n-OH. The ω’ and α’ terminals are found to play an important role in a formation of three dimensional networks of natural rubber, i.e. branching and crosslinking; the higher the molecular weight, the larger is the number of branching points. The formation of three dimensional networks is concerned with a biosynthesis of natural rubber on a surface of a rubber particle in latex stage.
