The Enzyme Database

Your query returned 3 entries.    printer_iconPrintable version



EC 2.1.1.295     
Accepted name: 2-methyl-6-phytyl-1,4-hydroquinone methyltransferase
Reaction: (1) S-adenosyl-L-methionine + 2-methyl-6-phytylbenzene-1,4-diol = S-adenosyl-L-homocysteine + 2,3-dimethyl-6-phytylbenzene-1,4-diol
(2) S-adenosyl-L-methionine + 2-methyl-6-all-trans-nonaprenylbenzene-1,4-diol = S-adenosyl-L-homocysteine + plastoquinol
(3) S-adenosyl-L-methionine + 6-geranylgeranyl-2-methylbenzene-1,4-diol = S-adenosyl-L-homocysteine + 6-geranylgeranyl-2,3-dimethylbenzene-1,4-diol
For diagram of tocopherol biosynthesis, click here and for diagram of tocotrienol biosynthesis, click here
Other name(s): VTE3 (gene name); 2-methyl-6-solanyl-1,4-hydroquinone methyltransferase; MPBQ/MSBQ methyltransferase; MPBQ/MSBQ MT
Systematic name: S-adenosyl-L-methionine:2-methyl-6-phytyl-1,4-benzoquinol C-3-methyltransferase
Comments: Involved in the biosynthesis of plastoquinol, as well as vitamin E (tocopherols and tocotrienols).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Shintani, D.K., Cheng, Z. and DellaPenna, D. The role of 2-methyl-6-phytylbenzoquinone methyltransferase in determining tocopherol composition in Synechocystis sp. PCC6803. FEBS Lett. 511 (2002) 1–5. [DOI] [PMID: 11821038]
2.  Cheng, Z., Sattler, S., Maeda, H., Sakuragi, Y., Bryant, D.A. and DellaPenna, D. Highly divergent methyltransferases catalyze a conserved reaction in tocopherol and plastoquinone synthesis in cyanobacteria and photosynthetic eukaryotes. Plant Cell 15 (2003) 2343–2356. [DOI] [PMID: 14508009]
3.  Van Eenennaam, A.L., Lincoln, K., Durrett, T.P., Valentin, H.E., Shewmaker, C.K., Thorne, G.M., Jiang, J., Baszis, S.R., Levering, C.K., Aasen, E.D., Hao, M., Stein, J.C., Norris, S.R. and Last, R.L. Engineering vitamin E content: from Arabidopsis mutant to soy oil. Plant Cell 15 (2003) 3007–3019. [DOI] [PMID: 14630966]
[EC 2.1.1.295 created 2014]
 
 
EC 2.5.1.116     
Accepted name: homogentisate geranylgeranyltransferase
Reaction: geranylgeranyl diphosphate + homogentisate = diphosphate + 6-geranylgeranyl-2-methylbenzene-1,4-diol + CO2
For diagram of the homogentisate pathways, click here
Glossary: 6-geranylgeranyl-2-methylbenzene-1,4-diol = MGGBQ
Other name(s): HGGT; slr1736 (gene name)
Systematic name: geranylgeranyl-diphosphate:homogentisate geranylgeranyltransferase
Comments: Requires Mg2+ for activity. Involved in the biosynthesis of the vitamin E, tocotrienols. While the enzyme from the bacterium Synechocystis PCC 6803 has higher activity with phytyl diphosphate (EC 2.5.1.115, homogentisate phytyltransferase), the enzymes from barley, rice and wheat have only a low activity with that substrate [2].
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Collakova, E. and DellaPenna, D. Isolation and functional analysis of homogentisate phytyltransferase from Synechocystis sp. PCC 6803 and Arabidopsis. Plant Physiol. 127 (2001) 1113–1124. [PMID: 11706191]
2.  Cahoon, E.B., Hall, S.E., Ripp, K.G., Ganzke, T.S., Hitz, W.D. and Coughlan, S.J. Metabolic redesign of vitamin E biosynthesis in plants for tocotrienol production and increased antioxidant content. Nat. Biotechnol. 21 (2003) 1082–1087. [DOI] [PMID: 12897790]
3.  Yang, W., Cahoon, R.E., Hunter, S.C., Zhang, C., Han, J., Borgschulte, T. and Cahoon, E.B. Vitamin E biosynthesis: functional characterization of the monocot homogentisate geranylgeranyl transferase. Plant J. 65 (2011) 206–217. [DOI] [PMID: 21223386]
[EC 2.5.1.116 created 2014]
 
 
EC 5.5.1.24     
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 and for diagram of 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
References:
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. [DOI] [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. [DOI] [PMID: 12913173]
[EC 5.5.1.24 created 2013]
 
 


Data © 2001–2021 IUBMB
Web site © 2005–2021 Andrew McDonald