Espy Stephanie C, Keasling Jay D, Castillón Javier, Cornish Katrina
Department of Chemical Engineering, University of California, Berkeley, CA 94720, USA.
Arch Biochem Biophys. 2006 Apr 15;448(1-2):13-22. doi: 10.1016/j.abb.2006.01.009. Epub 2006 Feb 3.
The rubber-producing tree, Ficus elastica (the Indian rubber tree), requires the same substrates for rubber production as other rubber-producing plants, such as Hevea brasiliensis (the Brazilian or Para rubber tree), the major source of commercial natural rubber in the world, and Parthenium argentatum (guayule), a widely studied alternative for natural rubber production currently under commercial development. Rubber biosynthesis can be studied, in vitro, using purified, enzymatically active rubber particles, an initiator such as FPP, IPP as the source of monomer, and a metal cofactor such as Mg2+. However, unlike H. brasiliensis and P. argentatum, we show that enzymatically active rubber particles purified from F. elastica are able to synthesize rubber, in vitro, in the absence of added initiator. In this paper, we characterize, for the first time, the kinetic differences between initiator-dependent rubber biosynthesis, and initiator-independent rubber biosynthesis, and the effect of cofactor concentration on both of these processes.
产橡胶的榕树（印度橡胶树），与其他产橡胶植物，如世界商业天然橡胶的主要来源巴西橡胶树（巴西三叶橡胶树）以及目前正在商业开发中、作为天然橡胶生产广泛研究替代品的银胶菊，需要相同的底物来生产橡胶。橡胶生物合成可以在体外进行研究，使用纯化的、具有酶活性的橡胶颗粒、一种引发剂如法呢基焦磷酸（FPP）、异戊烯基焦磷酸（IPP）作为单体来源以及一种金属辅因子如镁离子（Mg2+）。然而，与巴西橡胶树和银胶菊不同，我们发现从榕树纯化得到的具有酶活性的橡胶颗粒能够在体外不添加引发剂的情况下合成橡胶。在本文中，我们首次表征了依赖引发剂的橡胶生物合成与不依赖引发剂的橡胶生物合成之间的动力学差异，以及辅因子浓度对这两个过程的影响。
