EC	4.2.3.22
Accepted name:	germacradienol synthase
Reaction:	(2E,6E)-farnesyl diphosphate + H2O = (1E,4S,5E,7R)-germacra-1(10),5-dien-11-ol + diphosphate
Other name(s):	germacradienol/germacrene-D synthase; 2-trans,6-trans-farnesyl-diphosphate diphosphate-lyase [(1E,4S,5E,7R)-germacra-1(10),5-dien-11-ol-forming]
Systematic name:	(2E,6E)-farnesyl-diphosphate diphosphate-lyase [(1E,4S,5E,7R)-germacra-1(10),5-dien-11-ol-forming]
Comments:	Requires Mg2+ for activity. H-1si of farnesyl diphosphate is lost in the formation of (1E,4S,5E,7R)-germacra-1(10),5-dien-11-ol. Formation of (-)-germacrene D involves a stereospecific 1,3-hydride shift of H-1si of farnesyl diphosphate. Both products are formed from a common intermediate [2]. Other enzymes produce germacrene D as the sole product using a different mechanism. The enzyme mediates a key step in the biosynthesis of geosmin (see EC 4.1.99.16 geosmin synthase), a widely occurring metabolite of many streptomycetes, bacteria and fungi [2]. Also catalyses the reaction of EC 4.2.3.75, (-)-germacrene D synthase.
References:	1.  Cane, D.E. and Watt, R.M. Expression and mechanistic analysis of a germacradienol synthase from Streptomyces coelicolor implicated in geosmin biosynthesis. Proc. Natl. Acad. Sci. USA 100 (2003) 1547–1551. [PMID: 12556563] 2.  He, X. and Cane, D.E. Mechanism and stereochemistry of the germacradienol/germacrene D synthase of Streptomyces coelicolor A3(2). J. Am. Chem. Soc. 126 (2004) 2678–2679. [PMID: 14995166] 3.  Gust, B., Challis, G.L., Fowler, K., Kieser, T. and Chater, K.F. PCR-targeted Streptomyces gene replacement identifies a protein domain needed for biosynthesis of the sesquiterpene soil odor geosmin. Proc. Natl. Acad. Sci. USA 100 (2003) 1541–1546. [PMID: 12563033]
[EC 4.2.3.22 created 2006, modified 2011]
EC	4.2.3.73
Accepted name:	valencene synthase
Reaction:	(2E,6E)-farnesyl diphosphate = (+)-valencene + diphosphate
Systematic name:	(2E,6E)-farnesyl-diphosphate diphosphate-lyase (valencene-forming)
Comments:	The recombinant enzyme from Vitis vinifera gave 49.5% (+)-valencene and 35.5% (-)-7-epi-α-selinene. Initial cyclization gives (+)-germacrene A in an enzyme bound form which is not released to the medium.
References:	1.  Lucker, J., Bowen, P. and Bohlmann, J. Vitis vinifera terpenoid cyclases: functional identification of two sesquiterpene synthase cDNAs encoding (+)-valencene synthase and (-)-germacrene D synthase and expression of mono- and sesquiterpene synthases in grapevine flowers and berries. Phytochemistry 65 (2004) 2649–2659. [PMID: 15464152]
[EC 4.2.3.73 created 2011]
EC	4.2.3.75
Accepted name:	(-)-germacrene D synthase
Reaction:	(2E,6E)-farnesyl diphosphate = (-)-germacrene D + diphosphate
Glossary:	(-)-germacrene D = (1E,6E,8S)-1-methyl-5-methylidene-8-(propan-2-yl)cyclodeca-1,6-diene
Systematic name:	(2E,6E)-farnesyl-diphosphate diphosphate-lyase [(-)-germacrene-D-forming]
Comments:	In Solidago canadensis the biosynthesis results in the pro-R hydrogen at C-1 of the farnesy diphosphate ending up at C-11 of the (-)-germacrene D [1]. With Streptomyces coelicolor the pro-S hydrogen at C-1 ends up at C-11 of the (-)-germacrene D [2].
References:	1.  Schmidt, C.O., Bouwmeester, H.J., Franke, S. and König, W.A. Mechanisms of the biosynthesis of sesquiterpene enantiomers (+)- and (-)-germacrene D in Solidago canadensis. Chirality 11 (1999) 353–362. 2.  He, X. and Cane, D.E. Mechanism and stereochemistry of the germacradienol/germacrene D synthase of Streptomyces coelicolor A3(2). J. Am. Chem. Soc. 126 (2004) 2678–2679. [PMID: 14995166] 3.  Lucker, J., Bowen, P. and Bohlmann, J. Vitis vinifera terpenoid cyclases: functional identification of two sesquiterpene synthase cDNAs encoding (+)-valencene synthase and (-)-germacrene D synthase and expression of mono- and sesquiterpene synthases in grapevine flowers and berries. Phytochemistry 65 (2004) 2649–2659. [PMID: 15464152] 4.  Prosser, I., Altug, I.G., Phillips, A.L., Konig, W.A., Bouwmeester, H.J. and Beale, M.H. Enantiospecific (+)- and (-)-germacrene D synthases, cloned from goldenrod, reveal a functionally active variant of the universal isoprenoid-biosynthesis aspartate-rich motif. Arch. Biochem. Biophys. 432 (2004) 136–144. [PMID: 15542052]
[EC 4.2.3.75 created 2011]
EC	4.2.3.77
Accepted name:	(+)-germacrene D synthase
Reaction:	(2E,6E)-farnesyl diphosphate = (+)-germacrene D + diphosphate
Glossary:	(+)-germacrene D = (1E,6E,8R)-1-methyl-5-methylidene-8-(propan-2-yl)cyclodeca-1,6-diene
Systematic name:	(2E,6E)-farnesyl-diphosphate diphosphate-lyase [(+)-germacrene-D-forming]
Comments:	Requires Mg2+, Mn2+, Ni2+ or Co2+. The formation of (+)-germacrene D involves a 1,2-hydride shift whereas for (-)-germacrene D there is a 1,3-hydride shift (see EC 4.2.3.75).
References:	1.  Picaud, S., Olsson, M.E., Brodelius, M. and Brodelius, P.E. Cloning, expression, purification and characterization of recombinant (+)-germacrene D synthase from Zingiber officinale. Arch. Biochem. Biophys. 452 (2006) 17–28. [PMID: 16839518]
[EC 4.2.3.77 created 2011]
EC	4.2.3.86
Accepted name:	7-epi-α-selinene synthase
Reaction:	(2E,6E)-farnesyl diphosphate = 7-epi-α-selinene + diphosphate
Glossary:	7-epi-α-selinene = (2S,4aR,8aR)-4a,8-dimethyl-2-(prop-1-en-2-yl)-1,2,3,4,4a,5,6,8a-octahydronaphthalene
Systematic name:	(2E,6E)-farnesyl-diphosphate diphosphate-lyase (7-epi-α-selinene-forming)
Comments:	The recombinant enzyme from Vitis vinifera forms 49.5% (+)-valencene (cf. EC 4.2.3.73, valencene synthase) and 35.5% (-)-7-epi-α-selinene. Initial cyclization gives (+)-germacrene A in an enzyme bound form which is not released to the medium.
References:	1.  Lucker, J., Bowen, P. and Bohlmann, J. Vitis vinifera terpenoid cyclases: functional identification of two sesquiterpene synthase cDNAs encoding (+)-valencene synthase and (-)-germacrene D synthase and expression of mono- and sesquiterpene synthases in grapevine flowers and berries. Phytochemistry 65 (2004) 2649–2659. [PMID: 15464152] 2.  Martin, D.M., Toub, O., Chiang, A., Lo, B.C., Ohse, S., Lund, S.T. and Bohlmann, J. The bouquet of grapevine (Vitis vinifera L. cv. Cabernet Sauvignon) flowers arises from the biosynthesis of sesquiterpene volatiles in pollen grains. Proc. Natl. Acad. Sci. USA 106 (2009) 7245–7250. [PMID: 19359488]
[EC 4.2.3.86 created 2011]
EC	4.2.3.91
Accepted name:	cubebol synthase
Reaction:	(2E,6E)-farnesyl diphosphate + H2O = cubebol + diphosphate
Other name(s):	Cop4
Systematic name:	(2E,6E)-farnesyl-diphosphate diphosphate-lyase (cyclizing, cubebol-forming)
Comments:	Requires Mg2+. The enzyme gives 28% cubebol, 29% (-)-germacrene D, 10% (+)-δ-cadinene and traces of several other sesquiterpenoids. See also EC 4.2.3.75 (–)-germacrene D synthase and EC 4.2.3.13 (+)-δ-cadinene synthase.
References:	1.  Lopez-Gallego, F., Agger, S.A., Abate-Pella, D., Distefano, M.D. and Schmidt-Dannert, C. Sesquiterpene synthases Cop4 and Cop6 from Coprinus cinereus: catalytic promiscuity and cyclization of farnesyl pyrophosphate geometric isomers. ChemBioChem 11 (2010) 1093–1106. [PMID: 20419721]
[EC 4.2.3.91 created 2011]
EC	4.2.3.111
Accepted name:	(-)-α-terpineol synthase
Reaction:	geranyl diphosphate + H2O = (-)-α-terpineol + diphosphate
Systematic name:	geranyl-diphosphate diphosphate-lyase [cyclizing, (-)-α-terpineol-forming]
Comments:	The enzyme has been characterized from Vitis vinifera (grape). Also forms some 1,8-cineole and traces of other monoterpenoids.
References:	1.  Martin, D.M. and Bohlmann, J. Identification of Vitis vinifera (-)-α-terpineol synthase by in silico screening of full-length cDNA ESTs and functional characterization of recombinant terpene synthase. Phytochemistry 65 (2004) 1223–1229. [PMID: 15184006] 2.  Lucker, J., Bowen, P. and Bohlmann, J. Vitis vinifera terpenoid cyclases: functional identification of two sesquiterpene synthase cDNAs encoding (+)-valencene synthase and (-)-germacrene D synthase and expression of mono- and sesquiterpene synthases in grapevine flowers and berries. Phytochemistry 65 (2004) 2649–2659. [PMID: 15464152]
[EC 4.2.3.111 created 2012]