EC 2.5.1.90     
Accepted name: all-trans-octaprenyl-diphosphate synthase
Reaction: (2E,6E)-farnesyl diphosphate + 5 isopentenyl diphosphate = 5 diphosphate + all-trans-octaprenyl diphosphate
Glossary: all-trans-octaprenyl diphosphate = OPP
Other name(s): octaprenyl-diphosphate synthase; octaprenyl pyrophosphate synthetase; polyprenylpyrophosphate synthetase; terpenoidallyltransferase; terpenyl pyrophosphate synthetase; trans-heptaprenyltranstransferase; trans-prenyltransferase
Systematic name: (2E,6E)-farnesyl-diphosphate:isopentenyl-diphosphate farnesyltranstransferase (adding 5 isopentenyl units)
Comments: This enzyme catalyses the condensation reactions resulting in the formation of all-trans-octaprenyl diphosphate, the isoprenoid side chain of ubiquinone-8 and menaquinone-8. The enzyme adds five isopentenyl diphosphate molecules sequentially to farnesyl diphosphate with trans stereochemistry
References:
1.  Fujisaki, S., Nishino, T. and Katsuki, H. Isoprenoid synthesis in Escherichia coli. Separation and partial purification of four enzymes involved in the synthesis. J. Biochem. 99 (1986) 1327–1337. [PMID: 3519603]
2.  Asai, K., Fujisaki, S., Nishimura, Y., Nishino, T., Okada, K., Nakagawa, T., Kawamukai, M. and Matsuda, H. The identification of Escherichia coli ispB (cel) gene encoding the octaprenyl diphosphate synthase. Biochem. Biophys. Res. Commun. 202 (1994) 340–345. [PMID: 8037730]
[EC 2.5.1.90 created 2010]