L-Tryptophan

Tryptophan (IUPAC-IUBMB abbreviation: Trp or W; IUPACabbreviation: L-Trp or D-Trp; sold for medical use as Tryptan) is one of the 22standard amino acids and an essential amino acid in the human diet, asdemonstrated by its growth effects on rats. It is encoded in the standardgenetic code as the codon UGG. Only the L-stereoisomer of tryptophan is used instructural or enzyme proteins, but the R -stereoisomer is occasionally found innaturally produced peptides (for example, the marine venom peptide contryphan).The distinguishing structural characteristic of tryptophan is that it containsan indole functional group.