| EC |
2.1.1.64 |
| Accepted name: |
3-demethylubiquinol 3-O-methyltransferase |
| Reaction: |
S-adenosyl-L-methionine + 3-demethylubiquinol-n = S-adenosyl-L-homocysteine + ubiquinol-n |
|
For diagram of ubiquinol biosynthesis, click here |
| Glossary: |
3-demethylubiquinol-n = 3-hydroxy-2-methoxy-5-methyl-6-(all-trans-polyprenyl)-1,4-benzoquinol |
| Other name(s): |
5-demethylubiquinone-9 methyltransferase; OMHMB-methyltransferase; 2-octaprenyl-3-methyl-5-hydroxy-6-methoxy-1,4-benzoquinone methyltransferase; S-adenosyl-L-methionine:2-octaprenyl-3-methyl-5-hydroxy-6-methoxy-1,4-benzoquinone-O-methyltransferase; COQ3 (gene name); Coq3 O-methyltransferase; 3-demethylubiquinone-9 3-methyltransferase; ubiG (gene name, ambiguous) |
| Systematic name: |
S-adenosyl-L-methionine:3-hydroxy-2-methoxy-5-methyl-6-(all-trans-polyprenyl)-1,4-benzoquinol 3-O-methyltransferase |
| Comments: |
This enzyme is involved in ubiquinone biosynthesis. Ubiquinones from different organisms have a different number of prenyl units (for example, ubiquinone-6 in Saccharomyces, ubiquinone-9 in rat and ubiquinone-10 in human), and thus the natural substrate for the enzymes from different organisms has a different number of prenyl units. However, the enzyme usually shows a low degree of specificity regarding the number of prenyl units. For example, the human COQ3 enzyme can restore biosynthesis of ubiquinone-6 in coq3 deletion mutants of yeast [3]. The enzymes from yeast, Escherichia coli and rat also catalyse the methylation of 3,4-dihydroxy-5-all-trans-polyprenylbenzoate [3] (a reaction that is classified as EC 2.1.1.114, polyprenyldihydroxybenzoate methyltransferase). |
| Links to other databases: |
BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 63774-48-1 |
| References: |
| 1. |
Houser, R.M. and Olson, R.E. 5-Demethylubiquinone-9-methyltransferase from rat liver mitochondria. Characterization, localization, and solubilization. J. Biol. Chem. 252 (1977) 4017–4021. [PMID: 863914] |
| 2. |
Leppik, R.A., Stroobant, P., Shineberg, B., Young, I.G. and Gibson, F. Membrane-associated reactions in ubiquinone biosynthesis. 2-Octaprenyl-3-methyl-5-hydroxy-6-methoxy-1,4-benzoquinone methyltransferase. Biochim. Biophys. Acta 428 (1976) 146–156. [DOI] [PMID: 769831] |
| 3. |
Poon, W.W., Barkovich, R.J., Hsu, A.Y., Frankel, A., Lee, P.T., Shepherd, J.N., Myles, D.C. and Clarke, C.F. Yeast and rat Coq3 and Escherichia coli UbiG polypeptides catalyze both O-methyltransferase steps in coenzyme Q biosynthesis. J. Biol. Chem. 274 (1999) 21665–21672. [DOI] [PMID: 10419476] |
| 4. |
Jonassen, T. and Clarke, C.F. Isolation and functional expression of human COQ3, a gene encoding a methyltransferase required for ubiquinone biosynthesis. J. Biol. Chem. 275 (2000) 12381–12387. [DOI] [PMID: 10777520] |
|
| [EC 2.1.1.64 created 1982, modified 2011] |
| |
|
| |
|
Printable version