IUBMB Enzyme Nomenclature


Accepted name: tocopherol cyclase

Reaction: (1) δ-tocopherol = 2-methyl-6-phytylbenzene-1,4-diol
(2) γ-tocopherol = 2,3-dimethyl-6-phytylbenzene-1,4-diol
(3) δ-tocotrienol = 6-geranylgeranyl-2-methylbenzene-1,4-diol
(4) γ-tocotrienol = 6-geranylgeranyl-2,3-dimethylbenzene-1,4-diol

For diagram of tocopherol biosynthesis, click here or tocotrienol biosynthesis click here

Other name(s): VTE1 (gene name); SXD1 (gene name); δ/γ-tocopherol lyase (decyclizing)

Systematic name: δ/γ-tocopherol lyase (ring-opening)

Comments: The enzyme has been described from plants and cyanobacteria. It has similar activity with all four listed benzoquinol substrates. Involved in the biosynthesis of vitamin E tocopherols and tocotrienols.

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


1. Porfirova, S., Bergmuller, E., Tropf, S., Lemke, R. and Dormann, P. Isolation of an Arabidopsis mutant lacking vitamin E and identification of a cyclase essential for all tocopherol biosynthesis. Proc. Natl. Acad. Sci. USA 99 (2002) 12495-12500. [PMID: 12213958]

2. Sattler, S.E., Cahoon, E.B., Coughlan, S.J. and DellaPenna, D. Characterization of tocopherol cyclases from higher plants and cyanobacteria. Evolutionary implications for tocopherol synthesis and function. Plant Physiol. 132 (2003) 2184-2195. [PMID: 12913173]

[EC created 2013]

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