Figure 4.

Reaction mechanisms of Prdx isoforms. The peroxidatic cysteine residue of Prdxs reacts with H₂O₂ to release H₂O and form a sulfenic acid (SOH) intermediate. SOH is resolved with a second monomer to form an intermolecular disulfide bond in typical 2-Cys Prdxs (Prdx1–4). Atypical 2-Cys Prdx (Prdx5) forms an intra-subunit disulfide in the identical subunit, which is distinct from typical 2-Cys Prdxs. The 1-Cys Prdx (Prdx6) react with H₂O₂ to form a SOH intermediate, which forms a disulfide bond with other proteins or small thiol molecules to reduce the peroxidatic cysteine.