FIG. 5.

The catalytic cycle for Prdx6 and role of GSH transferase (GT). Prdx6 (PxSH) is shown indicating the active-site sulfhydryl on C47. πGSH S-transferase (GTSH) also is shown with its active sulfhydryl group indicated (by coincidence, also at C47). In its antioxidant role, Prdx6 interacts with an oxidant (H₂O₂) to generate the sulfenic acid (reaction 1), which then interacts with the SH of πGST to generate the Prdx6:πGST heterodimer (reaction 2). The GSH bound to the πGST glutathionylates Prdx6, liberating πGST (reaction 3). Finally, a second GSH reduces the –SSG bond and regenerates the active (reduced) enzyme (reaction 4). Modified from Ralat et al. (81).