Tocopherol cyclase

Manetsch, R., Zheng, L, Reymond, M.T., Woggon, W.D. and Reymond, J.L (2004) A catalytic antibody against a tocopherol cyclase inhibitor. Chemistry, 10,2487-2506. 

Sattler, S.E. Cahoon, E.B. Coughlan, S.J. DellaPeima, D. 2003. Characterization of tocopherols cyclases from higher plants and cyanobacteria. Evolutionary implications for tocopherols synthesis and function. Plant Physiol. 132 2184-2195. 

Figure 1. Tocopherol biosynthesis in plants. Enzyme abbreviation El-homogentisate phytyltransferase E2-2-methyl-6-phytylplastoquinol methyltransferase E3-tocopherol cyclase E4 -tocopherol methyltransferase. y-tocopherol (y-T) is the major component (>70%) found in com seeds oil.

FIGURE 18.3 Alpha-tocopherol (vitamin E) biosynthesis pathway. Enzymes shown in boxes include the following TTA, tyrosine transaminase (EC 2.6.1.5) HPPD, 4-hydroxyphenylp)fruvate dioxygenase (EC 1.13.11.27) HPT, homogentisate phytyltransferase (EC 2.5.1.115) VTE3, MBQD methyltransferase (EC 2.1.1.195) VTEl, tocopherol cyclase (EC 5.5.1.24) G-TMT, gamma-tocopherol methyltransferase (EC 2.1.1.95). 

Porfirova, S., Bergmuller, E., Tropf, S., Lemke, R., and Dormann, R, Isolation of an Arabidopsis mutant lacking vitamin E and identification of a cyclase essential for all tocopherol biosynthesis, Proc. Natl. Acad. Sci. U.S.A. 99 (19), 12495-12500, 2002. 

---