The molecule is an S-substituted glutathione that is glutathione in which the hydrogen of the thiol has been replaced by a hexyl group (PDB entry: 1PN9).
(2S)-2-amino-5-[[(2R)-1-(carboxymethylamino)-3-hexylsulfanyl-1-oxopropan-2-yl]amino]-5-oxopentanoic acid