ID 2.5.1.90 DE all-trans-octaprenyl-diphosphate synthase. AN octaprenyl pyrophosphate synthetase. AN terpenyl pyrophosphate synthetase. AN trans-heptaprenyltranstransferase. AN trans-prenyltransferase. CA (2E,6E)-farnesyl diphosphate + 5 isopentenyl diphosphate = all-trans- CA octaprenyl diphosphate + 5 diphosphate. CC -!- This enzyme catalyzes the condensation reactions resulting in the CC formation of all-trans-octaprenyl diphosphate, the isoprenoid side CC chain of ubiquinone-8 and menaquinone-8. CC -!- The enzyme adds five isopentenyl diphosphate molecules sequentially CC to farnesyl diphosphate with trans stereochemistry. DR P0AD57, ISPB_ECOLI ; P44916, ISPB_HAEIN ; P0AD58, ISPB_SHIFL ; //