EC	4.2.1.123
Accepted name:	tetrahymanol synthase
Reaction:	tetrahymanol = squalene + H2O
Glossary:	tetrahymanol = gammaceran-3β-ol
Systematic name:	squalene hydro-lyase (tetrahymanol-forming)
Comments:	The reaction occurs in the reverse direction.
References:	1.  Saar, J., Kader, J.C., Poralla, K. and Ourisson, G. Purification and some properties of the squalene-tetrahymanol cyclase from Tetrahymena thermophila. Biochim. Biophys. Acta 1075 (1991) 93–101. [PMID: 1892870] 2.  Giner, J.L., Rocchetti, S., Neunlist, S., Rohmer, M. and Arigoni, D. Detection of 1,2-hydride shifts in the formation of euph-7-ene by the squalene-tetrahymanol cyclase of Tetrahymena pyriformis. Chem. Commun. (Camb.) (2005) 3089–3091. [PMID: 15959594]
[EC 4.2.1.123 created 2011]
EC	4.2.1.129
Accepted name:	squalene—hopanol cyclase
Reaction:	hopan-22-ol = squalene + H2O
Other name(s):	squalene—hopene cyclase (ambiguous)
Systematic name:	hopan-22-ol hydro-lyase
Comments:	The enzyme produces the cyclization products hopene (cf. EC 5.4.99.17) and hopanol from squalene at a constant ratio of 5:1.
References:	1.  Hoshino, T., Nakano, S., Kondo, T., Sato, T. and Miyoshi, A. Squalene-hopene cyclase: final deprotonation reaction, conformational analysis for the cyclization of (3R,S)-2,3-oxidosqualene and further evidence for the requirement of an isopropylidene moiety both for initiation of the polycyclization cascade and for the formation of the 5-membered E-ring. Org Biomol Chem 2 (2004) 1456–1470. [PMID: 15136801] 2.  Sato, T., Kouda, M. and Hoshino, T. Site-directed mutagenesis experiments on the putative deprotonation site of squalene-hopene cyclase from Alicyclobacillus acidocaldarius. Biosci. Biotechnol. Biochem. 68 (2004) 728–738. [PMID: 15056909]
[EC 4.2.1.129 created 2011]