Reaction: geranyl diphosphate = γ-terpinene + diphosphate
For diagram of reaction click here.
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.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:
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]