IUBMB Enzyme Nomenclature


Accepted name: β-amyrin synthase

Reaction: (3S)-2,3-epoxy-2,3-dihydrosqualene = β-amyrin

For diagram of reaction click here.

Other name(s): 2,3-oxidosqualene β-amyrin cyclase; AsbAS1; BPY; EtAS; GgbAS1; LjAMY1; MtAMY1; PNY; BgbAS

Systematic name: (3S)-2,3-epoxy-2,3-dihydrosqualene mutase (cyclizing, β-amyrin-forming)

Comments: Some organism possess a monofunctional β-amyrin synthase [3,4,6-11], other have a multifunctional enzyme that also catalyses the synthesis of α amyrin (EC [5] or lupeol (EC [6].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:


1. Abe, I, Ebizuka, Y., Seo, S. and Sankawa, U. Purification of squalene-2,3-epoxide cyclases from cell suspension cultures of Rabdosia japonica Hara. FEBS Lett. 249 (1989) 100-104.

2. Abe, I., Sankawa, U. and Ebizuka, Y. Purification of 2,3-oxdosqualene:β-amyrin cyclase from pea seedlings. Chem. Pharm. Bull. 37 (1989) 536.

3. Kushiro, T., Shibuya, M. and Ebizuka, Y. β-Amyrin synthase-cloning of oxidosqualene cyclase that catalyzes the formation of the most popular triterpene among higher plants. Eur. J. Biochem. 256 (1998) 238-244. [PMID: 9746369]

4. Hayashi, H., Huang, P., Kirakosyan, A., Inoue, K., Hiraoka, N., Ikeshiro, Y., Kushiro, T., Shibuya, M. and Ebizuka, Y. Cloning and characterization of a cDNA encoding β-amyrin synthase involved in glycyrrhizin and soyasaponin biosyntheses in licorice. Biol. Pharm. Bull. 24 (2001) 912-916. [PMID: 11510484]

5. Husselstein-Muller, T., Schaller, H. and Benveniste, P. Molecular cloning and expression in yeast of 2,3-oxidosqualene-triterpenoid cyclases from Arabidopsis thaliana. Plant Mol. Biol. 45 (2001) 75-92. [PMID: 11247608]

6. Iturbe-Ormaetxe, I., Haralampidis, K., Papadopoulou, K. and Osbourn, A.E. Molecular cloning and characterization of triterpene synthases from Medicago truncatula and Lotus japonicus. Plant Mol. Biol. 51 (2003) 731-743. [PMID: 12683345]

7. Zhang, H., Shibuya, M., Yokota, S. and Ebizuka, Y. Oxidosqualene cyclases from cell suspension cultures of Betula platyphylla var. japonica: molecular evolution of oxidosqualene cyclases in higher plants. Biol. Pharm. Bull. 26 (2003) 642-650. [PMID: 12736505]

8. Hayashi, H., Huang, P., Takada, S., Obinata, M., Inoue, K., Shibuya, M. and Ebizuka, Y. Differential expression of three oxidosqualene cyclase mRNAs in Glycyrrhiza glabra. Biol. Pharm. Bull. 27 (2004) 1086-1092. [PMID: 15256745]

9. Kajikawa, M., Yamato, K.T., Fukuzawa, H., Sakai, Y., Uchida, H. and Ohyama, K. Cloning and characterization of a cDNA encoding β-amyrin synthase from petroleum plant Euphorbia tirucalli L. Phytochemistry 66 (2005) 1759-1766. [PMID: 16005035]

10. Basyuni, M., Oku, H., Tsujimoto, E., Kinjo, K., Baba, S. and Takara, K. Triterpene synthases from the Okinawan mangrove tribe, Rhizophoraceae. FEBS J. 274 (2007) 5028-5042. [PMID: 17803686]

11. Liu, Y., Cai, Y., Zhao, Z., Wang, J., Li, J., Xin, W., Xia, G. and Xiang, F. Cloning and functional analysis of a β-amyrin synthase gene associated with oleanolic acid biosynthesis in Gentiana straminea MAXIM. Biol. Pharm. Bull. 32 (2009) 818-824. [PMID: 19420748]

[EC created 2011]

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