Crossword clue: an amino acid that occurs in proteins; is essential for growth and normal metabolism; a precursor of niacin

The most common answer is tryptophan (10 letters).

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

Possible answers

tryptophan 10 letters wn-def

an amino acid that occurs in proteins; is essential for growth and normal metabolism; a precursor of niacin

tryptophane 11 letters wn-def

an amino acid that occurs in proteins; is essential for growth and normal metabolism; a precursor of niacin