Exhibits glutathione (GSH) S-transferase activity toward 1-chloro-2,4-dinitrobenzene (CDNB); however this activity is as low as 1% of that of GstA. Also displays a GSH-dependent peroxidase activity toward cumene hydroperoxide. Is involved in defense against oxidative stress, probably via its peroxidase activity. glutathione + RX = a halide anion + an S-substituted glutathione + H(+) GSH transferase activity is inhibited by S-hexyl glutathione. kcat is 0.11 sec(-1) for the GSH transferase reaction with CDNB as substrate. Activity decreases as pH is lowered from neutral to acidic. Deletion of yfcF decreases the resistance of the bacteria to hydrogen peroxide. Belongs to the GST superfamily.