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 (PubMed:10681558, PubMed:11741925, PubMed:15210711). Can act alternatively as peroxidase and molecular chaperone. Oxidative stress and heat shock exposure cause a reversible shift of the protein structure from low MW species to high MW complexes, triggering a peroxidase-to-chaperone functional switch. The chaperone function of the protein enhances resistance to heat shock (PubMed:15163410). [thioredoxin]-dithiol + a hydroperoxide = [thioredoxin]-disulfide + an alcohol + H2O Homodimer; disulfide-linked, upon oxidation. By peroxides. 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 typical 2-Cys peroxiredoxin, C(R) is provided by the other dimeric subunit to form an intersubunit disulfide. The disulfide is subsequently reduced by thioredoxin. Present with 4820 molecules/cell in log phase SD medium. Belongs to the peroxiredoxin family. AhpC/Prx1 subfamily.