Submitted to: Polymer Preprints
Publication Type: Proceedings
Publication Acceptance Date: 3/6/2009
Publication Date: 3/6/2009
Citation: Puskas, J.E., Chiang, C.K., Heidenreich, A., Xie, W., McMahan, C.M. 2009. Investigation of the composition and growth of in-vitro natural rubber using high resolution size exclusion chromatography. Polymer Preprints 2009, 50(1):232-233. Interpretive Summary: Natural rubber (NR) is a polymer composed of isoprene units in cis-1,4 enchainment. Hevea brasiliensis is the foremost important commercial source among the rubber producing plant species. However, limited habitat for rubber plantations, narrow genetic variation, coupled with increasing demand for high quality rubber lead to a need for alternative natural rubber resources. The USDA’s Domestic Natural Rubber project, aimed at developing natural rubber-producing crops in the USA, is collaborating with The University of Akron (Ohio) in an NSF funded project on rubber biosynthesis. National Science Foundation funding (NSF-CHE-0616834) was secured (Puskas, PI, McMahan, co-PI) for “Novel Processes for the Synthesis of Polyisoprene and Polyisoprene-Polyisobutylene Block and Graft Copolymers based on Natural Rubber Biosynthesis”. The CRC (Collaborative Research in Chemistry) GOALIE program includes international (Prof. Alain Deffieux, France, Prof. Herbert Mayr, Germany) and industrial (The Goodyear Tire & Rubber Company) participation. Natural rubber has outstanding properties which have never been duplicated by synthetics. One reason may be the almost-perfect stereochemistry of rubber produced by the rubber transferase enzyme. The research collaborators recently proposed that NR biosynthesis proceeds via a carbocationic polymerization mechanism. Based on this theory, a general mechanism termed “Natural Living Carbocationic Polymerization” (NCLP) was developed. In this paper, high-resolution SEC was able to detect growth of both high and low MW rubber for in vitro NR biosynthesis.
Technical Abstract: Recently, Puskas et al. have proposed that the molecular mechanism of natural rubber (NR) biosynthesis is through carbocationic polymerization. To acquire further insight into the mechanism, in vitro NR biosynthesis experiments are performed at the United States Department of Agriculture (USDA) with combinations of enzymatically active rubber particles from Hevea brasiliensis,(RRIM600), isopentenyl diphosphate (IPP), farnesyl diphosphate (FPP), isoprene (IP), Mg2+, and ethylene diamine tetraacetic acid (EDTA). In this study, high resolution size exclusion chromatography (SEC) is used to decipher the distribution of polyisoprenoids and oligoisoprenoids of rubber particles to monitor the growth of in vitro natural rubber.