EC 1.14.13.207      
Transferred entry: ipsdienol synthase. Now EC 1.14.14.31, ipsdienol synthase
[EC 1.14.13.207 created 2015, deleted 2016]
 
 
EC 1.14.14.31     
Accepted name: ipsdienol synthase
Reaction: myrcene + [reduced NADPH—hemoprotein reductase] + O2 = (R)-ipsdienol + [oxidized NADPH—hemoprotein reductase] + H2O
Glossary: myrcene = 7-methyl-3-methyleneocta-1,6-diene
ipsdienol = 2-methyl-6-methyleneocta-2,7-dien-4-ol
Other name(s): myrcene hydroxylase; CYP9T2; CYP9T3
Systematic name: myrcene,NADPH—hemoprotein reductase:O2 oxidoreductase (hydroxylating)
Comments: A cytochrome P-450 heme-thiolate protein. Involved in the insect aggregation pheromone production. Isolated from the pine engraver beetle, Ips pini. A small amount of (S)-ipsdienol is also formed. In vitro it also hydroxylated (+)- and (–)-α-pinene, 3-carene, and (+)-limonene, but not α-phellandrene, (–)-β-pinene, γ-terpinene, or terpinolene.
References:
1.  Sandstrom, P., Welch, W.H., Blomquist, G.J. and Tittiger, C. Functional expression of a bark beetle cytochrome P450 that hydroxylates myrcene to ipsdienol. Insect Biochem. Mol. Biol. 36 (2006) 835–845. [PMID: 17046597]
2.  Song, M., Kim, A.C., Gorzalski, A.J., MacLean, M., Young, S., Ginzel, M.D., Blomquist, G.J. and Tittiger, C. Functional characterization of myrcene hydroxylases from two geographically distinct Ips pini populations. Insect Biochem. Mol. Biol. 43 (2013) 336–343. [PMID: 23376633]
[EC 1.14.14.31 created 2015 as EC 1.14.13.207, transferred 2016 to EC 1.14.14.31]
 
 
EC 4.2.3.52     
Accepted name: (4S)-β-phellandrene synthase (geranyl-diphosphate-cyclizing)
Reaction: geranyl diphosphate = (4S)-β-phellandrene + diphosphate
Other name(s): phellandrene synthase; (-)-β-phellandrene synthase; (-)-(4S)-β-phellandrene synthase
Systematic name: geranyl-diphosphate diphosphate-lyase [cyclizing; (4S)-β-phellandrene-forming]
Comments: Requires Mn2+. Mg2+ is not effective [1]. Some (-)-α-phellandrene is also formed [3]. The reaction involves a 1,3-hydride shift [4].
References:
1.  Savage, T.J., Hatch, M.W. and Croteau, R. Monoterpene synthases of Pinus contorta and related conifers. A new class of terpenoid cyclase. J. Biol. Chem. 269 (1994) 4012–4020. [PMID: 8307957]
2.  Bohlmann, J., Phillips, M., Ramachandiran, V., Katoh, S. and Croteau, R. cDNA cloning, characterization, and functional expression of four new monoterpene synthase members of the Tpsd gene family from grand fir (Abies grandis). Arch. Biochem. Biophys. 368 (1999) 232–243. [PMID: 10441373]
3.  Wagschal, K., Savage, T.J. and Croteau, R. Isotopically sensitive branching as a tool for evaluating multiple product formation by monoterpene cyclases. Tetrahedron 31 (1991) 5933–5944.
4.  LaFever, R.E. and Croteau, R. Hydride shifts in the biosynthesis of the p-menthane monoterpenes α-terpinene, γ-terpinene, and β-phellandrene. Arch. Biochem. Biophys. 301 (1993) 361–366. [PMID: 8460944]
[EC 4.2.3.52 created 2010]
 
 
EC 4.2.3.110     
Accepted name: (+)-sabinene synthase
Reaction: geranyl diphosphate = (+)-sabinene + diphosphate
Glossary: (+)-sabinene = (+)-thuj-4(10)-ene = (1R,5R)-1-isopropyl-4-methylenebicyclo[3.1.0]hexane
Other name(s): SS
Systematic name: geranyl-diphosphate diphosphate-lyase [cyclizing, (+)-sabinene-forming]
Comments: Isolated from Salvia officinalis (sage). The recombinant enzyme gave 63% (+)-sabinene, 21% γ-terpinene, and traces of other monoterpenoids. See EC 4.2.3.114 γ-terpinene synthase.
References:
1.  Wise, M.L., Savage, T.J., Katahira, E. and Croteau, R. Monoterpene synthases from common sage (Salvia officinalis). cDNA isolation, characterization, and functional expression of (+)-sabinene synthase, 1,8-cineole synthase, and (+)-bornyl diphosphate synthase. J. Biol. Chem. 273 (1998) 14891–14899. [PMID: 9614092]
2.  Peters, R.J. and Croteau, R.B. Alternative termination chemistries utilized by monoterpene cyclases: chimeric analysis of bornyl diphosphate, 1,8-cineole, and sabinene synthases. Arch. Biochem. Biophys. 417 (2003) 203–211. [PMID: 12941302]
[EC 4.2.3.110 created 2012]
 
 
EC 4.2.3.114     
Accepted name: γ-terpinene synthase
Reaction: geranyl diphosphate = γ-terpinene + diphosphate
Glossary: γ-terpinene = 1-isopropyl-4-methylcyclohexa-1,4-diene
Other name(s): OvTPS2; ClcTS
Systematic name: geranyl-diphosphate diphosphate-lyase (cyclizing, γ-terpinene-forming)
Comments: Isolated from Thymus vulgaris (thyme) [1,2], Citrus limon (lemon) [3], Citrus unshiu (satsuma) [4] and Origanum vulgare (oregano) [5]. Requires Mg2+. Mn2+ less effective. The reaction involves a 1,2-hydride shift. The 5-pro-S hydrogen of geranyl diphosphate is lost. Traces of several other monoterpenoids are formed in addition to γ-terpinene.
References:
1.  Alonso, W.R. and Croteau, R. Purification and characterization of the monoterpene cyclase γ-terpinene synthase from Thymus vulgaris. Arch. Biochem. Biophys. 286 (1991) 511–517. [PMID: 1897973]
2.  LaFever, R.E. and Croteau, R. Hydride shifts in the biosynthesis of the p-menthane monoterpenes α-terpinene, γ-terpinene, and β-phellandrene. Arch. Biochem. Biophys. 301 (1993) 361–366. [PMID: 8460944]
3.  Lücker, J., El Tamer, M.K., Schwab, W., Verstappen, F.W., van der Plas, L.H., Bouwmeester, H.J. and Verhoeven, H.A. Monoterpene biosynthesis in lemon (Citrus limon). cDNA isolation and functional analysis of four monoterpene synthases. Eur. J. Biochem. 269 (2000) 3160–3171. [PMID: 12084056]
4.  Suzuki, Y., Sakai, H., Shimada, T., Omura, M., Kumazawa, S. and Nakayama, T. Characterization of γ-terpinene synthase from Citrus unshiu (Satsuma mandarin). Biofactors 21 (2004) 79–82. [PMID: 15630174]
5.  Crocoll, C., Asbach, J., Novak, J., Gershenzon, J. and Degenhardt, J. Terpene synthases of oregano (Origanum vulgare L.) and their roles in the pathway and regulation of terpene biosynthesis. Plant Mol. Biol. 73 (2010) 587–603. [PMID: 20419468]
[EC 4.2.3.114 created 2012]
 
 
EC 4.2.3.115     
Accepted name: α-terpinene synthase
Reaction: geranyl diphosphate = α-terpinene + diphosphate
Glossary: α-terpinene = 1-isopropyl-4-methylcyclohexa-1,3-diene
Systematic name: geranyl-diphosphate diphosphate-lyase (cyclizing, α-terpinene-forming)
Comments: The enzyme has been characterized from Dysphania ambrosioides (American wormseed). Requires Mg2+. Mn2+ is less effective. The enzyme will also use (3R)-linalyl diphosphate. The reaction involves a 1,2-hydride shift. The 1-pro-S hydrogen of geranyl diphosphate is lost.
References:
1.  Poulose, A.J. and Croteau, R. γ-Terpinene synthetase: a key enzyme in the biosynthesis of aromatic monoterpenes. Arch. Biochem. Biophys. 191 (1978) 400–411. [PMID: 736574]
2.  LaFever, R.E. and Croteau, R. Hydride shifts in the biosynthesis of the p-menthane monoterpenes α-terpinene, γ-terpinene, and β-phellandrene. Arch. Biochem. Biophys. 301 (1993) 361–366. [PMID: 8460944]
[EC 4.2.3.115 created 2012]
 
 


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