The Dual Functions of Thiol-Based Peroxidases in H2O2Scavenging and Signaling

Abstract

Thiol-based peroxidases consist of the peroxiredoxins (Prx) and the related glutathione peroxidase (GPx)-like enzymes. Their catalytic function is to reduce peroxides by using the reactivity of the cysteine residue, and their presumed primary physiologic role is to protect living organisms from peroxide toxicity. However, as peroxide-metabolizing enzymes, they also regulate hydrogen peroxide (H₂O₂) signaling. We review here enzymatic and biochemical attributes of thiol peroxidases that specify both distinctive peroxide-scavenging functions and the property of regulating H₂O₂ signaling. We then discuss possible thiol peroxidase physiologic functions, based on selected observations made in microorganisms and mammals.