Sagami H, Kurisaki A, Ogura K
Institute for Chemical Reaction Science, Tohoku University, Sendai, Japan.
J Biol Chem. 1993 May 15;268(14):10109-13.
The alpha-saturation reaction involved in the biosynthesis of dolichol has been investigated with rat liver preparations. Under improved in vitro conditions with 10,000 x g supernatant of rat liver homogenates in the presence of NADPH at pH 8.0, dolichol was synthesized from isopentenyl diphosphate and Z,E,E-geranylgeranyl diphosphate. Neither dolichyl diphosphate nor dolichyl phosphate was detected. The chain length distribution of the dolicohol was the same as that of dehydrodolichyl products. In an assay system containing dehydrodolichol, dehydrodolichyl phosphate, or dehydrodolichyl diphosphate as a substrate, dehydrodolichol was predominantly converted into dolichol. The enzyme that catalyzes the conversion of dehydrodolichol to dolichol was localized in microsomes. The reductase activity was stimulated 9-fold by the addition of a 100,000 x g soluble fraction. The reductase had an opimal pH at 8.0. These results indicate that dolichol is formed from dehydrodolichol in rat liver microsomes. The formation of dolichol from dehydrodolichol was also catalyzed by 10,000 x g supernatant of rat or pig testis homogenates.
已利用大鼠肝脏制剂对参与多萜醇生物合成的α-饱和反应进行了研究。在改进的体外条件下，于pH 8.0、存在NADPH的情况下，使用大鼠肝脏匀浆的10000×g上清液，由异戊烯基二磷酸和Z,E,E-香叶基香叶基二磷酸合成了多萜醇。未检测到二磷酸多萜醇和磷酸多萜醇。多萜醇的链长分布与脱氢多萜醇产物的相同。在含有脱氢多萜醇、磷酸脱氢多萜醇或二磷酸脱氢多萜醇作为底物的测定系统中，脱氢多萜醇主要转化为多萜醇。催化脱氢多萜醇转化为多萜醇的酶定位于微粒体中。通过添加100000×g可溶级分，还原酶活性提高了9倍。该还原酶的最适pH为8.0。这些结果表明，在大鼠肝脏微粒体中多萜醇由脱氢多萜醇形成。大鼠或猪睾丸匀浆的10000×g上清液也催化了脱氢多萜醇形成多萜醇的反应。
