Tryptophan

Tryptophan is an essential amino acid incorporated into proteins and used to produce serotonin, melatonin, and niacin. Humans must obtain it from food.

Protein biosynthesis: The cellular process of assembling proteins from amino acids according to genetic instructions. Ribosomes incorporate tryptophan into proteins wherever a gene specifies its codon.
Essential amino acid: An amino acid that an organism cannot synthesize in sufficient amounts and must obtain from its diet. Tryptophan is essential in humans, so adequate intake depends on food.
Amino acid: An organic molecule with amino and carboxyl groups; protein-building amino acids also have a distinctive side chain. Tryptophan is one of the 20 standard amino acids used to build proteins.
Phenylalanine: An essential aromatic amino acid with a benzyl side chain. Both are aromatic essentials, but phenylalanine lacks tryptophan's indole nitrogen and major serotonin pathway.
Serotonin: A neurotransmitter and signaling molecule synthesized from tryptophan. Tryptophan is converted through 5-hydroxytryptophan into serotonin.
Dietary protein: Protein consumed in food and digested into amino acids and small peptides. Dietary protein is the principal source of tryptophan for human metabolism.
Indole: A fused benzene–pyrrole ring system found in tryptophan and many other molecules. Tryptophan's bulky indole side chain gives it distinctive chemical and protein interactions.
Tyrosine: An aromatic amino acid that is synthesized from phenylalanine and serves as a protein building block. Tyrosine feeds catecholamine synthesis, whereas tryptophan feeds serotonin synthesis.
Melatonin: A hormone that helps regulate sleep timing and circadian rhythms. The pineal gland converts serotonin, derived from tryptophan, into melatonin.
Tryptophan supplement: A dietary supplement containing tryptophan, commonly marketed for sleep or mood. Supplementation raises tryptophan intake, but evidence and safety depend on use and context.

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