Studies on the Biosynthesis of Natural Rubber

二磷酸异戊烯基（IPP）异构酶[EC 5.3.3.2]催化IPP可逆异构化为二磷酸二甲基烯基，被认为参与橡胶生物合成，但没有直接证据表明它在胶乳中存在。在巴西橡胶树离心胶乳冻干制备的c血清粉中发现了该酶的活性。结合橡胶的生物合成，测定了丙烯基转移酶在c -血清粉中的活性。主要产物为法尼酯二磷酸酯（C_<15>）和香叶基香叶基二磷酸酯（C_<20>）。此外，当二磷酸香叶烯基（C_<10>）作为烯丙基底物时，得到了二磷酸聚戊烯基（-C_<30>）。在DEAE-Toyopearl上对c -血清进行层析，得到了几个戊烯基转移酶组分。其中一个部分纯化的酶组分显示出产生链长大于C_<80>和C_<15>的聚戊烯基产物的活性。

Isopentenyl diphosphate (IPP) isomerase [EC 5.3.3.2], which catalyzes the reversible isomerization of IPP to dimethylallyl diphosphate, is presumed to be involved in rubber biosynthesis, but no direct evidence has been given for its occurrence in rubber latex. This enzyme activity was found in the C-serum powder prepared by lyophilization of centrifuged rubber latex of Hevea brasiliensis.In connection with the biosynthesis of rubber, prenyltransferase activities in the C-serum powder were examined. Farnesyl diphosphate (C_<15>) and geranylgeranyl diphosphate (C_<20>) were detected as major products. In addition, a polyprenyl diphosphate (-C_<30>) was obtained when geranyl diphosphate (C_<10>) was employed as the allylic substrate. When the C-serum was chromatographed on DEAE-Toyopearl, several prenyltransferase fractions were obtained. One of the partially purified enzyme fractions showed an activity of producing a polyprenyl product with a chain length longer than C_<80> as well as a C_<15> product.