IUBMB Enzyme Nomenclature


Accepted name: presqualene diphosphate synthase

Reaction: 2 (2E,6E)-farnesyl diphosphate = presqualene diphosphate + diphosphate

For diagram of reaction click here.

Other name(s): SSL-1 (gene name); hpnD (gene name)

Systematic name: (2E,6E)-farnesyl-diphosphate:(2E,6E)-farnesyl-diphosphate farnesyltransferase (presqualene diphosphate-forming)

Comments: Isolated from the green alga Botryococcus braunii BOT22. Unlike EC, squalene synthase, where squalene is formed in one step from farnesyl diphosphate, in this alga the intermediate presqualene diphosphate is generated and released by this enzyme. This compound is then converted into either squalene (by EC, Botryococcus squalene synthase) or botryococcene (EC, botryococcene synthase).

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:


1. Niehaus, T.D., Okada, S., Devarenne, T.P., Watt, D.S., Sviripa, V. and Chappell, J. Identification of unique mechanisms for triterpene biosynthesis in Botryococcus braunii. Proc. Natl. Acad. Sci. USA 108 (2011) 12260-12265. [PMID: 21746901]

2. Pan, J.J., Solbiati, J.O., Ramamoorthy, G., Hillerich, B.S., Seidel, R.D., Cronan, J.E., Almo, S.C. and Poulter, C.D. Biosynthesis of squalene from farnesyl diphosphate in bacteria: three steps catalyzed by three enzymes. ACS Cent Sci 1 (2015) 77-82. [PMID: 26258173]

[EC created 2012]


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