Exhibits a very robust glutathione (GSH)-dependent disulfide-bond reductase activity toward the model substrate, 2-hydroxyethyl disulfide; the actual physiological substrates are not known. Has also a low GSH-dependent hydroperoxidase activity toward cumene hydroperoxide, but does not reduce H(2)O(2), tert-butyl hydroperoxide, benzyl peroxide, or lauroyl peroxide. Exhibits little or no GSH transferase activity with most typical electrophilic substrates, and has no detectable transferase activity using glutathionylspermidine (GspSH) as the nucleophilic substrate. Is involved in defense against oxidative stress, probably via its peroxidase activity. kcat is 180 sec(-1) for the disulfide-bond reductase reaction toward 2-hydroxyethyl disulfide. kcat is 0.27 sec(-1) for the hydroperoxidase reaction with cumene hydroperoxide. kcat is 0.1 sec(-1) for the GSH transferase reaction with chloro-2,4-dinitrobenzene (CDNB) as substrate. Homodimer. Deletion of yfcG decreases the resistance of the bacteria to hydrogen peroxide. The reductase activity of YfcG is unique in that no sulfhydryl groups in the protein appear to be covalently involved in the redox chemistry. Glutathionylspermidine (GspSH) binds YfcG about 10 times more tightly than GSH. Moreover, GSSG binds 100 times more tightly than GSH and 10 times more tightly than the GSH analog, GSO(3-) (PubMed:19537707). Belongs to the GST superfamily. Nu-class GSH transferase family.