Glutathione S-transferase, which conjugates reduced glutathione to a wide number of exogenous and endogenous hydrophobic electrophiles. glutathione + RX = a halide anion + an S-substituted glutathione + H(+) Inhibited by Fe(2+) and DTT. Slightly inhibited by SDS and Zn(2+). Activity is slightly increased by Mn(2+). Optimum pH is 6. Optimum temperature is 40 degrees Celsius. Belongs to the GST superfamily.