ExplorEnz: EC 4.2.3.108

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4.2.3.108

Accepted name:

1,8-cineole synthase

Reaction:

geranyl diphosphate + H₂O = 1,8-cineole + diphosphate

For diagram of menthane monoterpenoid biosynthesis, click here

Glossary:

1,8-cineole = 1,3,3-trimethyl-2-oxabicyclo[2.2.2]octane

Other name(s):

1,8-cineole cyclase; geranyl pyrophoshate:1,8-cineole cyclase; 1,8-cineole synthetase

Systematic name:

geranyl-diphosphate diphosphate-lyase (cyclizing, 1,8-cineole-forming)

Comments:

Requires Mn²⁺ or Zn²⁺. Mg²⁺ is less effective than either. 1,8-Cineole is the main product from the enzyme with just traces of other monoterpenoids. The oxygen atom is derived from water. The reaction proceeds via linalyl diphosphate and α-terpineol, the stereochemistry of both depends on the organism. However neither intermediate can substitute for geranyl diphosphate. The reaction in Salvia officinalis (sage) proceeds via (–)-(3R)-linalyl diphosphate [1-3] while that in Arabidopsis (rock cress) proceeds via (+)-(3S)-linalyl diphosphate [4].

Links to other databases:

BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 110637-19-9

References:

1.	Croteau, R., Alonso, W.R., Koepp, A.E. and Johnson, M.A. Biosynthesis of monoterpenes: partial purification, characterization, and mechanism of action of 1,8-cineole synthase. Arch. Biochem. Biophys. 309 (1994) 184–192. [DOI] [PMID: 8117108]
2.	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. [DOI] [PMID: 9614092]
3.	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. [DOI] [PMID: 12941302]
4.	Chen, F., Ro, D.K., Petri, J., Gershenzon, J., Bohlmann, J., Pichersky, E. and Tholl, D. Characterization of a root-specific Arabidopsis terpene synthase responsible for the formation of the volatile monoterpene 1,8-cineole. Plant Physiol. 135 (2004) 1956–1966. [DOI] [PMID: 15299125]
5.	Keszei, A., Brubaker, C.L., Carter, R., Kollner, T., Degenhardt, J. and Foley, W.J. Functional and evolutionary relationships between terpene synthases from Australian Myrtaceae. Phytochemistry 71 (2010) 844–852. [DOI] [PMID: 20399476]

[EC 4.2.3.108 created 2012]