The molecule is zwitterionic form of N(6)-[(indol-3-yl)acetyl]-L-lysine arising from transfer of a proton from the carboxy to the amino group; major species at pH 7.3. It is a tautomer of a N(6)-[(indol-3-yl)acetyl]-L-lysine.
(2S)-2-azaniumyl-6-[[2-(1H-indol-3-yl)acetyl]amino]hexanoate