Conjugation of reduced glutathione to a wide number of exogenous and endogenous hydrophobic electrophiles. Catalyzes the conjugation of leukotriene A4 with reduced glutathione (GSH) to form leukotriene C4. Can also catalyze the transfer of a glutathionyl group from glutathione (GSH) to 13(S),14(S)-epoxy-docosahexaenoic acid to form maresin conjugate in tissue regeneration 1 (MCTR1), a bioactive lipid mediator that possess potent anti-inflammatory and proresolving actions. glutathione + RX = a halide anion + an S-substituted glutathione + H(+) 1-chloro-2,4-dinitrobenzene + glutathione = 2,4-dinitrophenyl-S-glutathione + chloride + H(+) (13S,14S)-epoxy-(4Z,7Z,9E,11E,16Z,19Z)-docosahexaenoate + glutathione = (13R)-S-glutathionyl-(14S)-hydroxy-(4Z,7Z,9E,11E,16Z,19Z)-docosahexaenoate leukotriene C4 = glutathione + leukotriene A4 Homodimer. Belongs to the GST superfamily. Mu family.