Acts as a disulfide isomerase, interacting with incorrectly folded proteins to correct non-native disulfide bonds. DsbG and DsbC are part of a periplasmic reducing system that controls the level of cysteine sulfenylation, and provides reducing equivalents to rescue oxidatively damaged secreted proteins. Acts by transferring its disulfide bond to other proteins and is reduced in the process. DsbC is reoxidized by DsbD. Homodimer. Belongs to the thioredoxin family. DsbC subfamily.