Glutathione transferase M2-2 catalyzes conjugation of dopamine and dopa o-quinones

Human glutathione transferase M2-2 prevents the formation of neurotoxic ami nochrome and dopachrome by catalyzing the conjugation of dopamine and dopa o-quinone with glutathione. NMR analysis of dopamine and dopa o-quinone-glu tathione conjugates revealed that the addition of glutathione was at C-5 to form 5-S-glutathionyl-dopamine and 5-S-glutathionyldopa, respectively. Bot h conjugates were found to be resistant to oxidation by biological oxidizin g agents such as O-2, H2O2, and O-2(.-), and the glutathione transferase-ca talyzed reaction can therefore serve a neuroprotective antioxidant function . (C) 2000 Academic Press.