Main Entry: me·thi·o·nine

Pronunciation: \mə-ˈthī-ə-ˌnēn\

Function: noun

: a crystalline sulfur-containing essential amino acid C₅H₁₁NO₂S that occurs in the L-form as a constituent of many proteins (as casein and egg albumin), that is important especially as a source of sulfur for the biosynthesis of cysteine and as a source of methyl groups for transmethylation reactions (as in the biosynthesis of choline, creatine, and adrenaline), and that is used as a dietary supplement for human beings and their domestic mammals and poultry and in the treatment of fatty infiltration of the liver—abbreviation Met