A. Rattanapittayaporn¹, R. Wititsuwannakul¹, and D. Wititsuwannakul^2,*

¹ Department of Biochemistry, Faculty of Science, Prince of Songkla University, Hat-Yai 90112, Thailand

. ² Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand

Keywords: Rubber biosynthesis, Latex BF Membrane, Allylic isoprenes, Bacterial C₅₅ -UPP, Hevea brasiliensis

Rubber biosynthesis (RB) was shown to be very active and occurring in the bottom fraction (BF) particles, sediment membrane-bound organelles of centrifuged fresh latex. The extensive washed BF membrane (WBM) was unequivocally shown to possess enzymes system with high RB activity [1, 2]. Hevea rubber transferase gene (HRT) as recently cloned was shown to be RB active with WBM [3]. In contrast to previous studies with washed rubber particles (WRP), WBM was shown much more active in synthesis of new rubber molecules. Anionic surfactants SDS and DOC above critical micelle concentration (CMC) strongly activated new rubber formation by WBM. Proteins as fractionated from WBM by serial acetone extractions were still with high RB activity in mixed micelle with surfactants. Fractionated proteins also showed regulatory component in reconstitution RB assays. WBM enzymes system showed wide range for allylic isoprenes on initiating new rubber molecules. C₅₅- UPP prepared from M. luteus was effectively utilized by WBM for synthesis of new rubber, but the WRP was without any RB activity with UPP. Comparison among allylic isoprenes of different chain length showed that UPP was the most effective or preferred by WBM as allylic initiator for new rubber being formed compared to the shorter ones (C₂₀-GGPP, C₁₅-FPP, C₅-IPP). Differential solvents extraction (butanol & toluene/hexane) was employed for products separation.  Positive correlation was found between RB efficiency and the allylics chain length, WBM activity order are UPP>GGPP>FPP>>IPP. However, the shorter allylics accumulate more of oligoisoprenes than the longer allylic UPP. The results indicated that intermediates from UPP were faster converted into rubber products. Polyprenols of C₅₀-C₆₅ were found predominant in Hevea tissues as we have previously analyzed [4]. Therefore, it might be no surprise that the Hevea WBM enzymes system could effectively and efficiently utilize bacterial C₅₅-UPP in the active RB process. These findings might lend support to the recent idea on microbes producing rubber [5].

      论文来源：International Symposium on Biological Polyesters ,Auguest 22-27, 2004