Cornish K
USDA-ARS, Western Regional Research Center, Albany, CA 94710.
Eur J Biochem. 1993 Nov 15;218(1):267-71. doi: 10.1111/j.1432-1033.1993.tb18374.x.
In plants, the elongation of cis-1,4-polyisoprene (natural rubber, M(r) > 10(6) requires a small transallylic diphosphate (< or = C20) initiator. The trans-allylic diphosphates are hydrophilic cytosolic compounds, whereas cis-1,4-polyisoprene is hydrophobic and compartmentalised in subcellular rubber particles. In this paper, it is demonstrated that soluble trans-prenyl transferase from latex of Hevea brasiliensis functions solely as farnesyl diphosphate synthase, and plays no direct role in cis-1,4-polyisoprene elongation. The cis-1,4-prenyl transferase is firmly associated with the H. brasiliensis rubber particle, as is also the case in other rubber-producing species [Archer, B. L., Audley, B. G., Cockbain, E. G. & McSweeney, G. P. (1963) Biochem. J. 89, 565-574; Madhavan, S., Greenblatt, G. A., Foster, M. A. & Benedict, C. R. (1989) Plant Physiol. 89, 506-511; Siler, D. J. & Cornish, K. (1993) Phytochemistry 32, 1097-1102]. The experimental data explain and refute previous reports in which soluble trans-prenyl transferase isolated from H. brasilensis latex was attributed both trans-prenyl transferase and cis-prenyl transferase activities [Light, D. R. & Dennis, M. S. (1989) J. Biol. Chem. 264, 18589-18597; Light, D. R., Lazarus, R. A. & Dennis, M. S. (1989) J. Biol. Chem. 264, 18598-18607]. Thus, it appears that plant prenyl transferases are comparable to animal enzyme systems in which trans-prenyl transferases are soluble enzymes whilst cis-prenyl transferases are membrane-bound [Ericcson, J., Runquist, M., Thelin, A., Andersson, M., Chojnacki, T. & Dallner, G. (1992) J. Biol Chem. 268, 832-838].
在植物中，顺式-1,4-聚异戊二烯（天然橡胶，M(r)>10(6)）的延长需要一种小分子反式烯丙基二磷酸（≤C20）引发剂。反式烯丙基二磷酸是亲水性胞质化合物，而顺式-1,4-聚异戊二烯是疏水性的，并分隔在亚细胞橡胶颗粒中。本文证明，巴西橡胶树胶乳中的可溶性反式异戊烯基转移酶仅作为法尼基二磷酸合酶发挥作用，在顺式-1,4-聚异戊二烯延长过程中不发挥直接作用。顺式-1,4-异戊烯基转移酶与巴西橡胶树的橡胶颗粒紧密结合，其他产橡胶物种也是如此[阿彻，B.L.，奥德利，B.G.，科克贝恩，E.G.和麦克休尼，G.P.（1963年）《生物化学杂志》89，565 - 574；马达万，S.，格林布拉特，G.A.，福斯特，M.A.和本尼迪克特，C.R.（1989年）《植物生理学》89，506 - 511；西勒，D.J.和科尼什，K.（1993年）《植物化学》32，1097 - 1102]。实验数据解释并反驳了先前的报道，在这些报道中，从巴西橡胶树胶乳中分离出的可溶性反式异戊烯基转移酶被认为同时具有反式异戊烯基转移酶和顺式异戊烯基转移酶活性[莱特，D.R.和丹尼斯，M.S.（1989年）《生物化学杂志》264，18589 - 18597；莱特，D.R.，拉扎勒斯，R.A.和丹尼斯，M.S.（1989年）《生物化学杂志》264，18598 - 18607]。因此，似乎植物异戊烯基转移酶与动物酶系统类似，其中反式异戊烯基转移酶是可溶性酶，而顺式异戊烯基转移酶是膜结合酶[埃里克森，J.，伦奎斯特，M.，特林，A.，安德森，M.，乔纳基，T.和达尔纳，G.（1992年）《生物化学杂志》268，832 - 838]。
