EC - Squalene—hopene cyclase

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IntEnz Enzyme Nomenclature


Accepted name:
squalene—hopene cyclase
Systematic name:
squalene mutase (cyclizing, hop-22(29)-ene-forming)



The enzyme also produces the cyclization product hopan-22-ol by addition of water (cf. EC, squalene—hopanol cyclase). Hopene and hopanol are formed at a constant ratio of 5:1.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , DIAGRAM , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Protein domains and families: PROSITE:PDOC00825
Structural data: CSA , EC2PDB
Gene Ontology: GO:0051007
CAS Registry Number: 76600-69-6


  1. Hoshino, T. and Sato, T.
    Squalene-hopene cyclase: catalytic mechanism and substrate recognition.
    Chem. Commun. 291-301 (2002). [PMID: 12120044]
  2. Hoshino, T., Nakano, S., Kondo, T., Sato, T., 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 : 1456-1470 (2004). [PMID: 15136801]
  3. Sato, T., Kouda, M., Hoshino, T.
    Site-directed mutagenesis experiments on the putative deprotonation site of squalene-hopene cyclase from Alicyclobacillus acidocaldarius.
    Biosci. Biotechnol. Biochem. 68 : 728-738 (2004). [PMID: 15056909]
  4. Reinert, D. J., Balliano, G., Schulz, G. E.
    Conversion of squalene to the pentacarbocyclic hopene.
    Chem. Biol. 11 : 121-126 (2004). [PMID: 15113001]

[EC created 2002, modified 2011]