Tryptophan
Tryptophan is an esential amino acid that must be obtained from the human diet. it has the single amino acid code W (see Single_letter_amino_acid_codes) and the 3 letter code Trp. It is coded for in the genome by the nucleotide base sequence UGG [1].
Medical Uses
Tryptophan is also a drug which is used to treat depression, when other antidepressants have been otherwise uneffective.