Ericsson J, Thelin A, Chojnacki T, Dallner G
Department of Biochemistry, University of Stockholm, Sweden.
Eur J Biochem. 1991 Dec 18;202(3):789-96. doi: 10.1111/j.1432-1033.1991.tb16434.x.
The properties of rat liver cis-prenyl transferase, mediating the synthesis of polyisoprenoid pyrophosphate from trans,trans-farnesyl pyrophosphate and [3H]isopentenyl pyrophosphate were studied. The Km values for farnesyl pyrophosphate and isopentenyl pyrophosphate were found to be 25 microM and 4.4 microM, respectively. Appropriate conditions were established to measure the condensation reaction, which was linear during the first hour using 1 mg microsomal protein. Various detergents could solubilize the enzyme, but the presence of Triton X-100 was required during the incubation to obtain full activity. There was also an absolute requirement for Mg2+ and the pH maximum was 7.0. Inorganic phosphate, especially pyrophosphate, proved to be inhibitory. cis-Prenyl transferase is associated mainly with the cytoplasmic surface of rough microsomes and, to some extent, also with smooth I microsomes, but was almost absent from smooth II microsomes. At all localizations, the product is polyprenyl pyrophosphate and to some extent, also polyprenyl monophosphate. The isoprenoids formed contain 15-18 units in the presence of detergents and 16-20 units in the absence of detergents.
研究了大鼠肝脏顺式异戊烯基转移酶的特性，该酶介导从反，反-法呢基焦磷酸和[3H]异戊烯基焦磷酸合成聚异戊二烯焦磷酸。发现法呢基焦磷酸和异戊烯基焦磷酸的Km值分别为25 microM和4.4 microM。建立了合适的条件来测量缩合反应，使用1 mg微粒体蛋白时，该反应在第一个小时内呈线性。各种去污剂均可溶解该酶，但孵育过程中需要存在Triton X-100才能获得全部活性。对Mg2+也有绝对需求，最适pH为7.0。无机磷酸盐，尤其是焦磷酸，被证明具有抑制作用。顺式异戊烯基转移酶主要与粗糙微粒体的细胞质表面相关，在一定程度上也与光滑I微粒体相关，但在光滑II微粒体中几乎不存在。在所有定位中，产物均为聚异戊烯焦磷酸，在一定程度上也为聚异戊烯单磷酸。在有去污剂存在的情况下，形成的类异戊二烯含有15 - 18个单元，在无去污剂存在的情况下含有16 - 20个单元。
