EC 5.5.1.12     
Accepted name: copalyl diphosphate synthase
Reaction: geranylgeranyl diphosphate = (+)-copalyl diphosphate
Other name(s): (+)-copalyl-diphosphate lyase (decyclizing)
Systematic name: (+)-copalyl-diphosphate lyase (ring-opening)
Comments: In some plants, such as Salvia miltiorrhiza, this enzyme is monofunctional. In other plants this activity is often a part of a bifunctional enzyme. For example, in Selaginella moellendorffii this activity is catalysed by a bifunctional enzyme that also catalyses EC 4.2.3.131, miltiradiene synthase, while in the tree Abies grandis (grand fir) it is catalysed by a bifunctional enzyme that also catalyses EC 4.2.3.18, abietadiene synthase.
References:
1.  Peters, R.J., Ravn, M.M., Coates, R.M. and Croteau, R.B. Bifunctional abietadiene synthase: free diffusive transfer of the (+)-copalyl diphosphate intermediate between two distinct active sites. J. Am. Chem. Soc. 123 (2001) 8974–8978. [PMID: 11552804]
2.  Sugai, Y., Ueno, Y., Hayashi, K., Oogami, S., Toyomasu, T., Matsumoto, S., Natsume, M., Nozaki, H. and Kawaide, H. Enzymatic 13C labeling and multidimensional NMR analysis of miltiradiene synthesized by bifunctional diterpene cyclase in Selaginella moellendorffii. J. Biol. Chem. 286 (2011) 42840–42847. [PMID: 22027823]
3.  Peters, R.J. and Croteau, R.B. Abietadiene synthase catalysis: mutational analysis of a prenyl diphosphate ionization-initiated cyclization and rearrangement. Proc. Natl. Acad. Sci. USA 99 (2002) 580–584. [PMID: 11805316]
4.  Ravn, M.M., Peters, R.J., Coates, R.M. and Croteau, R. Mechanism of abietadiene synthase catalysis: stereochemistry and stabilization of the cryptic pimarenyl carbocation intermediates. J. Am. Chem. Soc. 124 (2002) 6998–7006. [PMID: 12059223]
5.  Peters, R.J. and Croteau, R.B. Abietadiene synthase catalysis: conserved residues involved in protonation-initiated cyclization of geranylgeranyl diphosphate to (+)-copalyl diphosphate. Biochemistry 41 (2002) 1836–1842. [PMID: 11827528]
[EC 5.5.1.12 created 2002, modified 2012]