Tryptophan

<p><b>Tryptophan</b> (IUPAC-IUBMB abbreviation: <b>Trp</b> or <b>W</b>; IUPAC abbreviation: L-Trp or D-Trp; sold for medical use as <b>Tryptan</b>)<sup id="cite_ref-2" class="reference"><a href="http://en.wikipedia.org/wiki/Tryptophan#cite_note-2">[2]</a></sup> is one of the 22 <a href="http://en.wikipedia.org/wiki/List_of_standard_amino_acids" title="List of standard amino acids" class="mw-redirect">standard amino acids</a> and an <a href="http://en.wikipedia.org/wiki/Essential_amino_acid" title="Essential amino acid">essential amino acid</a> in the <a href="http://en.wikipedia.org/wiki/Human" title="Human">human</a> diet.</p>