ABSTRACT
Peroxiredoxins (Prxs) are cysteine-dependent hydroperoxide reductases with varying specificities for their substrates, and typically very high catalytic efficiencies, with their best substrates on the order of 106–108 M-1 s-1. This implies a very specialized active site since a typical cysteine residue, even in its fully ionized state as a thiolate. To initiate the reaction, the absolutely conserved cysteine poised within the highly organized active site architecture is oxidized by the peroxide substrate to a sulfenic acid. The degree of sensitivity of individual Prxs toward hyperoxidation by their substrates is significantly controlled by structural and dynamic elements of these proteins, allowing tuning of this sensitivity to match the requirements for the biological function. Much current research focuses on gaining a better understanding of the forces at play in modulating catalytic power and hyperoxidation sensitivity of Prxs that link to their biological function.
