Peroxiredoxins: guardians against oxidative stress and modulators of peroxide signaling

• Prxs are ubiquitous defense enzymes and in some cases signaling regulators.
• ROOH orientation and polarization in the active site promotes Prx activity.
• The activated, catalytic cysteine can be susceptible to inactivation by hyperoxidation.
• Srx-mediated repair of hyperoxidation restores activity in some organisms.
• Regulated Prxs link peroxide metabolism and signaling.

Peroxiredoxins (Prxs) are a ubiquitous family of cysteine-dependent peroxidase enzymes that play dominant roles in regulating peroxide levels within cells. These enzymes, often present at high levels and capable of rapidly clearing peroxides, display a remarkable array of variations in their oligomeric states and susceptibility to regulation by hyperoxidative inactivation and other post-translational modifications. Key conserved residues within the active site promote catalysis by stabilizing the transition state required for transferring the terminal oxygen of hydroperoxides to the active site (peroxidatic) cysteine residue. Extensive investigations continue to expand our understanding of the scope of their importance as well as the structures and forces at play within these critical defense and regulatory enzymes.