The aroH operon shares a repressor with two E. coli operons named after this amino acid, and a decarboxylase converts its 5-hydroxy form to serotonin.  
This molecule's namesake "synthase" consists of an α-β-β-α complex whose active sites are joined by a solvent-filled tunnel, according to the structure determined by Hyde, Miles, and Davies.  Unlike two similar molecules whose hydroxylations also exhibit the NIH shift, this molecule's biosynthetic pathway includes anthranilate.  One intermediate in its degradation pathway spontaneously forms (*) quinolate, and that pathway's last seven steps are identical to that of lysine.  The aroH operon shares a repressor with two E. coli operons named after this amino acid, and a decarboxylase converts its 5-hydroxy form to serotonin.  For 10 points name this essential amino acid that contains an indole group, is symbolized W, and is responsible for feelings of sleepiness after eating too much turkey.
This molecule's namesake "synthase" consists of an α-β-β-α complex whose active sites are joined by a solvent-filled tunnel, according to the structure determined by Hyde, Miles, and Davies.  
{tryptophan} [accept {trp}; accept early {W}] (2) [DW]