Thiol-specific peroxidase that catalyzes the reduction of hydrogen peroxide and organic hydroperoxides to water and alcohols, respectively. Plays a role in cell protection against oxidative stress by detoxifying peroxides and as sensor of hydrogen peroxide-mediated signaling events. [thioredoxin]-dithiol + a hydroperoxide = [thioredoxin]-disulfide + an alcohol + H2O Monomer. More than twofold more abundant in the large cell variant (LCV) stage than in the small cell variant (SCV) stage (at protein level). LCVs are more metabolically active than SCVs. The active site is a conserved redox-active cysteine residue, the peroxidatic cysteine (C(P)), which makes the nucleophilic attack on the peroxide substrate. The peroxide oxidizes the C(P)-SH to cysteine sulfenic acid (C(P)-SOH), which then reacts with another cysteine residue, the resolving cysteine (C(R)), to form a disulfide bridge. The disulfide is subsequently reduced by an appropriate electron donor to complete the catalytic cycle. In this atypical 2-Cys peroxiredoxin, C(R) is present in the same subunit to form an intramolecular disulfide. The disulfide is subsequently reduced by thioredoxin. Belongs to the peroxiredoxin family. BCP/PrxQ subfamily.