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