Tocopherol O-methyltransferase (EC 2.1.1.95) is an enzyme that catalyzes the chemical reaction
This is a methylation reaction in which one of the vitamin E components, γ-tocopherol, is converted to the more commonly found α-tocopherol. The methyl group comes from the cofactor, S-adenosyl methionine (SAM), which becomes S-adenosyl-L-homocysteine (SAH). The enzymes from Arabidopsis thaliana and Capsicum annuum can also convert δ-tocopherol into β-tocopherol and are effective on tocotrienols, by addition of a methyl group at the same relative position as in γ-tocopherol. This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. The systematic name of this enzyme class is S-adenosyl-L-methionine:gamma-tocopherol 5-O-methyltransferase. This enzyme is also called gamma-tocopherol methyltransferase.
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