Peroxiredoxin （Prx） is a growing peroxidase family，whose mammalian members have been known to connect with cell proliferation，differentiation，and apoptosis. Many isoforms （about 50 proteins），collected in accordance to the amino acid sequence homology，particularly amino-terminal region containing active site cysteine residue，and the thiol-specific antioxidant activity，distribute throughout all the kingdoms. Among them，mammalian Prx consists of 6 different members grouped into typical 2-Cys，atypical 2-Cys Prx，and 1-Cys Prx. Except Prx VI belonging to 1-Cys Prx subgroup，the other five 2-Cys Prx isotypes have the thioredoxin-dependent peroxidase （TPx） activity utilizing thioredoxin，thioredoxin reductase，and NADPH as a reducing system. Mammalian Prxs are 20 – 30 kDa in molecular size and vary in subcellular localization: Prx I，II，and VI in cytosol，Prx III in mitochondria，Prx IV in ER and secretion，Prx V showing complicated distribution including peroxisome，mitochondria and cytosol. Prx VI is involved in redox regulation of the cell. Can reduce H2O2 and short chain organic，fatty acid，and phospholipid hydroperoxides. May play a role in the regulation of phospholipid turnover as well as in protection against oxidative injury.
