nutrient
Methionine
A sulfur-containing essential amino acid that can donate methyl groups.
Methionine starts many newly translated protein chains and supplies sulfur through pathways related to homocysteine and cysteine. Its activated form, S-adenosylmethionine, transfers methyl groups.
An activated methyl donor
S-adenosylmethionine is made from methionine and donates methyl groups to many substrates before returning to methionine-related metabolism.
Related topics
Methionine is used to build Protein
Methionine is one of the amino acids used to assemble proteins.
Worth knowing
It is required from dietary protein. Methionine is one of the essential amino acids and one of the main sulfur-containing amino acids in proteins.
It starts many protein chains. Methionine is the initiating amino acid encoded at the start of newly translated protein chains, although it may later be removed.
A closer look
Its sulfur can reach cysteine
Methionine metabolism can transfer sulfur through homocysteine-related pathways toward cysteine synthesis.
References
Source-checked local draft.
Human editorial review pending.
- NIH National Library of MedicineBiochemistry, Essential Amino AcidsChecked 2026-09-05
- NIH National Library of MedicineBiochemistry, Protein CatabolismChecked 2026-09-05
- NIH National Library of MedicineBiochemistry, Primary Protein StructureChecked 2026-09-05